Thanks, Gary. You are providing a useful service. I went solar from late 2021, including a year ago replacing my 30 year old gas-fired HWC with a 2-element one, controlled by an Eddi, as part of a MyEnergi suite. I had to wait more than a year for Zappi to be approved for use here in New Zealand, but that's another story. For me the addition of the Eddi was a no-brainer. My electricity provider offers 3 hours of FREE power for EV owners between 9pm and midnight. So I was already charging my Powerwall nightly and my EV once or twice weekly on this plan, and not keen on my summer surplus to the grid earning me peanuts. Now throughout the year, with the Eddi added, I top up the HWC every night for free. And with excess solar generation in summer that means all its hot water is leading towards my payback date, and in winter I just need a single 1-hour midday boost from the grid. And I can feel good about that free power being from NZ's hydroelectric generation...
Thanks for sharing this Ed - really useful insight, and I love the fact that you're getting free power at certainly times in the day - wow! If only we had more (and the right kind of) mountains here in the UK...!
Very interesting stuff, Gary, as always. Something I'm considering doing is using my eddi as a (very expensive) timer to heat my hot water during off-peak times, rather than as a diverter. The grid carbon intensity tends to be a lot lower overnight than during the day so this would have a good positive environmental benefit as well as potentially being financially beneficial too, particularly if the export rate during the day is higher than the import rate during off-peak times (as it is for Octopus Flux). If I didn't already have an eddi a cheap £20 immersion heater timer would offer the same benefits at a much lower cost too, so that might be something for folks to consider.
Thanks Tim - and I like your thinking! The off-peak Octopus Flux rate is pretty good. And, as you say, a basic timer unit (able to handle a 3kW load and daylight savings time adjustments) would be sufficient. Do the numbers work out ok for that?
I fitted my Eddi about 3 years ago and it's paid for itself already. At that time having a battery seemed hard to justify. How things have changed. I now have 9kWh of battery storage (approx. cost £5k) and view my Eddi as a cheap additional 8.5kWh of storage into the hot water tank (cost approx. £400) fitted myself. Its a nice feeling getting all your hot water from the sun for 8 months a year. Another Plus for the Eddi is the integration between Myenergi and the Agile tariff, automatically heating the hot water when a price plunge occurs below your target price (5p a kWh).
I want to fit my own water tank, I'm fairly confident in my abilities (apart from a unvented tank I'd leave that to a plumber). But worry about house insurance getting funny if I was ever to make a claim in the future and they found it was installed DIY. Thoughts?
Thanks, Gary. I will be getting my solar panels and batteries fitted in a couple of months time. I have cancelled my order for an Eddi as it was not as compatible as I would have liked with my Mixergy tank. Your excellent programme has reinforced my decision by to cancel. I will be using Octopus Flux.
Great stuff Jean, I would have liked to had a Mixenergy tank installed when my own tank failed last year, but the lead time was too long. Good luck with the Flux tariff and enjoy all that export income! 😀😀😀
This was an very interesting video @GaryDoesSolar. With regards to Mixergy, is it will worth having such a smart tank (I’m guessing, “yes”) @jeanh9641 and based on this video, I’m assuming it’s not worth having the Mixergy tank with the solar element, which is now an add on, to work off of solar (i.e export)?
Great video. My setup (panels, battery and diverter) is due to be installed in May. To me the main advantage is your basically fixing the price of your energy. Your case relies on energy companies paying that much for export into the future. I also have an ev and the flux tariff is more expensive to charge overnight. I’m still getting my head around it but I’d think I’d charge up overnight at 10p and use as much solar in the day as possible. But time will tell.
Hi Alan, thanks for kind feedback. I don't have an EV (yet) but if I did, then I'd likely be on Octopus Go. Flux is a great tariff, but it's really only suitable for those with solar and battery. Hope all goes well with your solar installation - May will be here in the blink of an eye!
Always nice to see a different perspective. The amount of home Control/Instrumentation that is being added to on grid domestic properties is mind boggling. People are almost engineering their homes. As an Instrumentation Eng. who understands it all, I would not have it in my house. It will eventually fail costing you equally or more to replace it than what you saved using it. All this "green energy" needs to be harnessed and handled externally at a national level and the end user simple buys it in at a reasonable cost just like years ago. By all means, install a cost effective PV panels to supplement your daytime use but the rest should be transparent keeping your house simple so you can get on with your life.
You raise some really good points. And it was the primary motivation for me to make this video about the mass consumer market: ua-cam.com/video/q6t0AAi5Jws/v-deo.html I'm not sure though that many early adopters of home solar PV can see past the way they think... Your word "transparent" is exactly it! :-)
**** On the Scenario A or Scenario B question **** I'm now fairly convinced that Scenario A is correct. Consider the following: 1. Your 1kWh will never make past your local substation. Instead, it will quickly be grabbed by your neighbour. That means your substation draws one less kWh than it would have done. And that means the grid can reduce its supply by 1kWh. And that reduction will come from the marginal generation source (i.e. fossil fuel). 2. Forget for a moment that we're dealing with diverters, and instead imagine thousands of domestic solar installations exporting energy on a sunny day. All of that export is counted as renewable energy in the supply mix. And we know that the more renewable energy there is, the less fossil fuel burning is required. Therefore, if you export 1kWh, you're preventing >1kWh of fossil fuel being burned to make up for that. Does anyone see this differently? Btw, if you enjoyed this video and would like to look deeper at the data, I recommend you watch Tim's video on solar diverters here: ua-cam.com/video/bMA2uudMgsQ/v-deo.html
This all makes sense of course unless you are on the old FIT system. Diverted is basically free hot water and still being paid for export (of course not as much as SEG)
This video doesn’t appear to have a place for early adopters on the fit contracts, where exporting pays about 4p for 50% of the energy it makes. Divert to make hot water is the financial option for us.
Thank you for sharing a very enjoyable video - we don't have a solar diverter, but do have a smart relay for turning the immersion on / off depending on available solar, time of day etc - we rely on the battery as our flexible energy dump. This video has convinced me we don't need anything cleverer than that 🙂. I suspect looking at the live grid emissions would be helpful in working out whether the gas boiler or the grid is likely to be greener. A couple of good options for comparing these are Carbon Intensity (UK only) [1] and Electricity Maps [2] - the day may significantly affect which is the better environmental option, especially given that some 'dirty' plants aren't overly responsive so the grid may turn off wind / solar on days with high renewable generation etc. Another area to consider is the energy required to heat your hot water. We found that using the immersion heater uses roughly a third of the energy to heat a days water when compared with gas. This is partly because of boiler efficiencies and partly because the heat exchanger in the tank heats from the bottom up, so we need to heat a full tank. With an immersion, we can get away with heating the top 30% of the tank which covers our usage on most days. [1] carbonintensity.org.uk/ [2] app.electricitymaps.com/map
We didn’t bother with a diverter when we had our solar installed in Nov 22 because it didn’t seem to make much sense even then. I simply installed a timer and heat the water using power from the battery in the morning and evening. The launch of the Octopus Flux tariff though seems to have really upended my assumptions of the best way to run our system. It now actually makes more sense to charge the battery from the grid during the 3hr overnight cheap rate, run the house from this during the day and export all our solar at the standard and premium rates.
Hi Stephen, I tend to agree. I'm working on a video on Octopus Flux at the moment as it happens - it's due to launch in a few weeks and I think it heralds the future of energy tariffs for those with solar and battery, just like Octopus Go did with EVs... :-)
Some observations:- 1) I have Octopus GO and heat our tank off peak at 7.5p/kWh, which lasts the 2 of us almost all day. 2) Shelly wifi power monitors, switches, and scenes can easily be set up to use solar that might otherwise be exported. No code writing required and much cheaper than diverters, too! I will have a Shelly 1PM monitoring my generation and a Shelly 1 switch to turn on my pool pump and heater when my generation goes above 1.5kW and off again when it goes below 0.5kW. The thresholds are easily changed and time delays can be added as desired. A similar system could be used with an immersion heater too. 3) Octopus only offer a 4p/kWh SEG if you have GO, but as far as I can see, I can sign up for Scottish Power's export tariff at 12p?
That's a brilliant setup, Mike - I need to take a look at these Shelly units. On 3) I wondered the same! That would be great if it were possible (maybe Octopus says you can have GO but you must take 4p SEG with it?)
Correction: I don't think I can use a Shelly PM1 to measure solar generation. It will have to be a Shelly EM with a CT Clamp. That puts the cost up from £40 to £75....
Thanks for the interesting video. However I purchased my Eddi last year so I think I'll stick with it. I knew at the time that the payback would be tricky but I like the idea of having some hot water without generating CO2 locally. I use Octopus Go in winter which means my export rate is only 4.5p - I will probably switch back to Agile Export (or whatever it is called at that point) in the summer. In the meantime I will have a word with my neighbour and ask her to stop using the vacuum cleaner so much.
Hi Graham, that made me laugh! :-) Btw, I really like the concept of Agile, but is it actually viable at the moment? The rates always seem to hover at the ceiling these days?
Great video Gary and food for thought. I recently switched from Go to Flux which was a no-brainer. I'm also waiting on a Solaredge diverter from my installer but now I'm thinking I should cancel as it does not seem worth it. I have an EV but rarely charge at home (free at work for the moment!). You really need to keep on top of the changing market and tariffs to get the most of things, and videos like yours really help to navigate the system. Thanks.
This is great feedback - thanks for the taking the time to write it - very much appreciated! I canceled my Eddi just before my installation and I'm happy I did that. All the best with whatever you decide!
Excellent presentation of a consideration that is up till now largely overlooked. Keep up the good work. I predict that in the near future there will be a demand for home owners with excess capacity at mid day to export at a good feed out rate from say 4 to 7 pm which can be provided from your battery, and you will have enough left to get you through the evening for many of the sunny, longer daylight days. As batteries become less expensive, it will be cost effective to get a larger storage battery and everybody wins. Then fossil fuel can be conserved to be used as a supplementary energy supply on cold, cloudy, windless days.
Thanks Gary. Interesting and thought provoking as ever. I have a 4kw solar array installed in 2011, so still get the highest feed in tariff, currently around 62p/kwh, but with an assumed export rate of 50% of generation at 4.5p/kwh. My understanding is that I cannot take advantage of the higher export rates available with Octopus without jeopardising my feed in tariff, and recent quotes for installation of a battery system have recommended a connection to batteries, but to do nothing that affects the supply to the solar generation meter. As all our heating comes from oil, and we only get 4.5p/kwh export tariff, I fitted an Immersun (an easy DIY job) about 8 years ago which enables us to turn off the oil boiler from April to October except for the dullest of days to provide 6 or 7 months of free HW which to me makes the diverter a no-brainer, particularly as it doesn't affect the 50% export assumption. In practice, we try to use the solar as we go by timing the use of dishwahers and washing machine use to the 3 hours either side of solar midday. At age 70, I'm looking for a payback time of no more than 10 years for obvious reasons. 🤣 However, we are in the fortunate position of having extra south and west facing roof space available for an additional 4kw array, so I'm always open to ideas. Presumably with ASHPs having an efficiency rating of up to 400% it would make sense for those who have them to divert power to that rather than to an immersion to provide HW?
Hi Roger, yeah, I wish it weren't so about my conclusions in that video - but over time, we are slowly but surely moving away from fossil fuels, and with talk of wholesale prices coming down again, maybe solar diverters still have life in them yet! 70 is still young in my book! :-) Regarding heat pumps, the more I hear about them, the more they just make sense for home heating and now water heating. I plan to make a video on them soon - it's just hard finding the time at the moment - and that's with me only working 3 days a week in my day job - lol
I'm also like you 4kw PV and have a FIT (from 2015), this is still better than the current best SEG rates overall. I have an ASHP, it does our heating and water, during winter it is working away at night a lot. Surely if there is a diverter keeping the water warm during the day this means less work for the ASHP during the day and when the sun goes down. Issue is when the ASHP kicks in it needs to draw more kwh than your solar can produce so will take from the grid even when sunny, a solar diverter will just use surplus so the ASHP should kick in less to keep water warm meaning less grid use overall. Seems to me in my case a diverter would be very beneficial so am going to install one.
At first sight, I don't get much benefit from my Hot Water Controller. But it's a relatively cheap investment. While you are right that you make more money on current export rates, the money saving actually exists in the future: - HW Cylinders don't last forever and they need to be replaced. But with a HW diverter, you can buy a cheaper HW cylinder that just has an immersion heated but no heating coil pipe. You can also delete all the associated plumbing pipework for the heating loop. In other words, you the opportunity to have a simpler, and therefore cheaper system at replacement time. - I have one less reason to keep my gas boiler. Before solar, I had a gas hob, hw heating and space heating. Now I just use it for space heating, and that gives me a stronger foundation from which to make the leap to alternate methods of heating (including air to air heat pumps which are much cheaper to buy than air to water systems).
Hi Anthony, I think you did well, buying when you did. Since then, prices have rocketed :-( You raise a great point about getting away from gas. We used to have a gas hob as well, but it's now electric. I'd love to get rid of the gas central heating, but without government help, the cost is too high for me. I've got quite a lot of rooms to heat so, although I love the idea of a2a heat pumps, I'd need quite a few, maybe? Interesting point about the hot water cylinder - we recently replaced ours (£1,500) so wouldn't want to go through that again in a hurry! Hope all is good with you. Looking forward to your next video :-)
Very useful and interesting - we are in the middle of having a heat pump installed - so it would be nice to have your calculator updated for this. (I tried increasing the gas boiler efficiency to 300% but no go). Also I am on the old tariff for solar as someone below mentioned - I think this means the payback period will be very quick but it would be nice to see it in black and white on your web-page.
Cheers Mark - and yeah, I am hoping to get round to the topic of heat pumps before long! So many topics to cover! And I'll sort a calculator for that when I do... :-)
Here in France, water heaters tend to be electric only, and the export rate is very low (and not possible if you install it yourself). However, with my SMA setup the Home Manager can switch on up to four appliances using WiFi plugs (€60) allowing cheap use during the day. And I'm not sure if overall fossil fuel conversion to electricity is anywhere near 50%. The EIA states that in the USA overall conversion efficiency is under 40%, with gas being the best at 45% (in 2019).
Hi David, sounds like you've got a pretty good setup there! Regarding fossil fuel conversion efficiencies, this makes the case for solar diverters even worse than I thought then - crikey!
These solar diverters are not a well known entity, at least among the tradies I've spoken with. I've been looking for something like this for over a year now for my electric only hot water system. I can't talk in generalities but all the off-peak hot water systems I've had over the years are electric only so my installation of one of these will always put me in front irrespective of the feed out tariff. Thank you. I now have a physical device type to talk to my electrician about getting installed.
Just moved to Outgoing Octopus Fixed for my export, so I guess its time to move back to gas water heating - feels wrong, but the figures don't lie. Good video as always.
Thanks Mathew - I'm just wanting to give people information and tools so they can reasonably accurately assess the benefits of a particular approach, before spending lots of money, only to have regret later. (Like me, I bought an Eddi and as I'm planning to make use of high export rates, it's no use to me any more - lol)
Thanks Gary. I have a solic 200, installed after two iboost failures. Worked very well. But since installing additional solar with batteries, and switching from FiT to SEG with Octopus, I've switched it off. Doesn't feel logical to export, but I think it's because we've been conditioned to use every bit of energy up ourselves.
You're most welcome. My videos are really just getting people to consider all the options open to them :-) Self-consumption is always best If you can, that's for sure!
Thank you for this. After using your utility I worked out I would never get payback on the Eddi due to be installed in 7 days time. Cancelled and £600 better off😊
You’re most welcome, Martin. And I did the same for my own installation week before last. It’s such a shame though as I really like the concept of the solar diverter 🤷♂️
Good question. The problem with thermal solar is that it’s expensive, less reliable, requires additional water pipe work and possibly a new tank. But more than any of that; it’s single use case. The only thing you can do with the sun’s energy is heat the water in your tank. And that doesn’t take too long to heat either. Solar PV on the other hand, can do the same, but it can also power your house, charge a large to power your house when the sun goes down, charge your EV, or even allow to make money via export. It’s also much more reliable 👍🏻
Not sure if I can fully agree with your logic here. Firstly, the assumption of my neighbor (or anyone else on the same grid for that matter) needing my extra produced Kwh is not very likely, as mostly when there's overproduction on my solar, there's overproduction basically everywhere as consumption during those hours is generally lower. Add to that the fact that if I don't divert that Kwh into my water, I'll be needing to heat that water using other sources at some point anyway (which I'll then be taking from those environmentally worse options). So if you're thinking financially, you'd divert unless you get a really high export fee (as in higher than what you pay for import), and if you're thinking environmentally, you'd still divert to avoid having to heat using other sources.
Hi Peter, thanks for taking the time to comment. Now, even on days where there is a great deal of solar, it only represents a small percentage of total generation that day (
A good well articulated view on how to use any excess generation. You could also make a similar argument (environmental) for battery storage, depending on when you decide to store the energy. If I decided to export my excess during peak at 5pm (or even discharge too) then charge up later in the evening/off peak when the grid is cleaner, then it would work out more environmentally beneficial, but probably not financial. That is of course if you are on Flux and have a large amount of solar where you ALWAYS have excess and battery to export when prices are high. A caveat though which I can now happily interject, If instead of the water being heated by Gas boiler it was heated by a heat pump, this would knock off the calculations, factor of 3 for hot water SCOP?
Thanks for the great feedback. My next video is about Octopus Flux - and I’ll be looking at the numbers around just what you describe. The more I hear about heat pumps, the more I love them! They’re just so efficient that diverting excess solar into them can only be a good strategy, whatever your motivation (financial or environmental) 😀
The SunSynk inverters have a built in auxiliary to feed the hot water from excess solar so no extra cost. On the question of export, Octopus only pay 4.1p if you are on GO and as I have 4/14p until June I can’t consider other options until that date
@@mikejoseph425 That's pretty cool about the SunSynk inverter! And completely understandable that you'd stay on Go at that rate for as long as you can! 🙂
We've just had solar installed, and so until we get the DNO sign off back (ETA 2 months!) and MCS certificate (couple of weeks), we were exporting for free. I purchased and installed a "solic 200" for £215. Not only is it about half the price of the iboost and Eddi devices, it also has a 10yr warranty compared with their 2yr warranties! It's not as "smart" as those devices, but I don't need it to be! With some clever wiring, you can ensure your inverter doesn't see the diverter usage and thus causes no battery drain issues.
Hi Ashleigh, how are you find your installation. After my nightmare of a journey (over a year!) my installation is going in as we speak :-) So far, everything is looking good. I bet you're happy to have yours up and running now, just in time for the longer sunnier days... I think you're right about the solar diverter units - they really don't need to be that complicated - the basic functions are sufficient. In the end, I asked my installer to take back the Eddi I ordered - I'm planning to export a lot (if I can) so no need for the Eddi. With the money, I've asked the installer to put in an EPS instead (just a little more than the cost of the Eddi). The battery drain issue was indeed one of the things worrying me about the Eddi as my batteries are DC-coupled - and that means the Eddi can't really see them...
Great vid, interesting points. I have a 4.5p off peak rate for 5 hours for another year so Octopus would be significantly more expensive and you have to move your supply to them to get those rates. But the 12p rate from Scottish Power looks like you don’t need to move to them. I’m on 5.6p SEG with EDF so 12p is over twice the rate. I export c. 50kWh on a sunny day at the moment and will likely get closer to 100 by the summer when GSHP heating for home gets turned off so this is quite a bonus. Thanks for bringing this rate to my attention!
Hi Craig, thanks for kind words, and also the detail on your situation. Even if just 50kWh export, that's amazing! Sounds like you likely can't go wrong with any of the Octopus tariffs, whatever you decided! :-)
@@GaryDoesSolar Some complex maths needs to be done when I come off the EDF off peak 5 hour 4.5p rate. I have 3 phase and 4 EVs as well as GSHP (I have no gas supply) at the house so I really use a lot of off peak (50kWh -150kWh most nights in autumn winter and spring) and Octopus have a lot higher off peak rate and a smaller window, 3 -4 hours I think. I'd have to see if the SEG rates were suffient to claw back the addittional off peak costs. Power abritrage I think they call it.
Came back to this so I could copy the link to forward to a Forum I'm a member of. Can't believe that I originally missed the Roman Emperor thumbnail - very good👍
Very good analysis. The public has very little understanding of marginal energy production. The problem is news reporters are not interested in doing the work to understand our energy supply system. They are part of the woke generation who never learned about critical reasoning from their education.
Thanks Phillip - and I'm hoping that my videos provide a good start for people trying to understand the world of solar, and that they don't just believe what I'm saying, but check things out for themselves :-)
Cannot believe the details keep moving so quickly (your report Gary is showing as a year old). Here Down Under we are now facing negative feed-in tarrifs. Currently my FIT is a meagre 5c so to me the solar diverter is a much cheaper and more attractive option than a battery with high upfront costs and doubtful savings before replacement become necessary ... not to mention fire risks. Your thoughts now please Gary. Is the situation changing likewise in UK as here in Oz?
Ah yes, Mark - you’re totally right - and this is the very topic of my next video which will be released tomorrow! Declining export rates and Solar diverters perhaps becoming back into fashion 😀👍🏻
Great video. Just a caveat. The high export tariffs from Octopus aren't available if you are on an ev tariff such as Go or Intelligent. You will be limited to the standard export tariff which is 4.5ppkWh I believe. I don't have a solar diverter and won't be getting one. I will simply switch my immersion on when there is excess solar. As I am on an ev tariff it pays to use as much as possible before exporting.
Great video, as always. I realise it’s out of context but a storage battery means you can divert solar and heat at the immersion’s full 3kw. If you have home automation something like a Shelly plus 1pm costing circa £20 could be used. That doesn’t resolve the environmental aspect though
Well here the "solar diverter" is a shelly + 3 phase relay with a home assistant automation (so like 50€) and I have no gas option to heat the water. So heating with the excess solar makes a lot of sense since otherwise I need to heat with electricity of the net.
Hi, thank you very much for such a detailed video. However, as EV owners on a smart tariff Octopus only allows a SEG of 4 p per kWh. So I am going for an Eddi. Hope it makes sense.
Cheers for the kind words 😀 Yeah, it’s a shame the EV tariffs have a low export rate compared to others :-/ Makes perfect sense to go for the Eddi then 👍🏻
Gary, thanks very much for a very timely release. Whilst mot touching on the subject of diverters, there is an extremely detailed comparison on the web looking at GO & FLUX. Apropo nothing to do with this, the actual quality & integrity of some solar sales staff have a lot to be desired 🤭 .... the Enphase system works for an hour longer each day than any other system .... virtually all inverters are made in China, you'll need 24 panels & 2 inverters (2 of us in the house) etc. 🤣. Thanks again for the fantastic output, enormously appreciated 🙏🏼
@@nicflanagan6662 That's so very kind of you to say. I work very hard on all these videos and I would say that 99% of the responses I get are great. But you know, there are always one or two people who just want to complain (like, I'm forcing them to watch my videos or something 🤣) - I could imagine this would cause a lot of UA-camrs to say "why do I bother?" and give up. But comments like yours make my day - thank you! 🙂 Some solar sales people remind me of some double-glazing salesmen 20-30 years ago. Whenever there's a new market forming, there will always be cowboys jumping in to make a quick buck, and I hate that. It's one of the reasons I started this channel in fact... Do you have a link to Go and Flux comparison please? I'm working on a Flux video just now...
Gas is 0.12/kWh, I’m exporting at 0.04/kWh, it still makes sense for me. If I have spare solar capacity then chances are the solar farms in the UK will have tonnes of it - so surely it’s more likely that shortfall is covered by renewable sources than coal?
Hi Will, great that a diverter still works for you 👍🏻 Are you on an EV tariff? I guess that’ll be the same for quite a few people. Regarding UK solar generation, today it only makes a small percentage of total supply (
that's an interesting point - if you have excess above your battery and baseload it may likely coincide with a higher percentage of solar in the grid mix (Scenario B)
Excellent video with your usual concise clarity. Thank you. I have an old FIT solar 2.5K installation with eddi and Zappi. I have an EV and am on the octopus intelligent tariff. This excellent tariff has saved me a huge percentage, and the data from myenergi and octopus has enabled me to maximise savings to the extent that I am using no more electricity than I was before I got the EV, saving on the tariff and almost 4K in fuel. On IO tariff, export rates are low. Do you have any thoughts on going bigger on solar plus battery, exporting on the flux tariff vs status quo, or just adding a battery. I’m retired, so EV can charge on excess solar during the day.
Hi Steve - thanks for the kind words :-) That's an amazing result with Intelligent Octopus - I'm soon to make a video on that tariff as it happens. It looks to be the eventual replacement for Octopus Go. Flux is a great tariff (I'm on that one) but if you have an EV, you're more likely to want to put any excess into that, rather than export. Many people with EVs see Go or IO as the best option...
Sorry to hear this. I hope more and more energy providers start to pay a better rate for export. If you think about it, your export goes straight to your neighbours - it highly unlikely to get past the sub-station. And that means the grid doesn't have to both supply (and more importantly, transmit) that same power to your neighbours. Everybody wins, in my view :-)
Gosh. More to think about. Ive had solar thermal for 15 years. Self installed and worked great until the controlled went pop. Now PV has come down I was considered switching and using a diverter. Heat pump install is beyond my means and insulation upgrades are a better use of finances. So heating water in winter is my biggest challenge if I ditch our trusty heat only boiler. Enjoy your £50 from Octopus. Thanks
Hi Chas, thanks - yeah - it's all PowerPoint animation! :-) Maybe one day I'll take the plunge and go for some proper animation software (another learning curve though). I moved from iMovie to Final Cut Pro last month and it's a great tool, but I'm on a trial and will have to pay for it soon! Regarding hate mail, I'll let you know! :-) ... but it's hard to argue with the numbers... market dynamics change and companies in that space have to adapt or die, I guess...
Interesting analysis, the issue of marginal (gas) vs. average (variable wind etc.) power generation is a good point, and there are reasons to look at either one. Two thoughts: 1. I think this just goes to show how the payback calculations are fraught with difficulty. I didn't order a diverter but did order a T-Smart immersion, which is cheaper and you can control it from your phone or put on a timer. After all, we've got a home battery so that can smooth out the difference between the solar generation and the immersion requirement (though that does mean extra cycling of the battery). It was over 8 months from ordering our system to installation, during which time Octopus Flux was invented. Who knows what the energy prices for gas and electricity will be in one year or five years' time? Having the control of the immersion heater is quite valuable for me, but I don't know if it will pay for itself. 2. What about heat pumps? If you've got a heat pump that heats hot water then I expect this changes the calculation again, since it will be so much more efficient than a gas boiler. If you've got a heat pump with a timer setting then you can run that off the solar and it is all the more efficient. Obviously then the case for a solar diverter drops off again.
Great points, Doug. I'm hoping to make a video on heat pumps before long. They just seem so in tune with solar and off-peak tariffs - like they were all made for each other :-)
Heat pumps I understand are better when on constantly. Especially in winter with heating going you just want the heat pump to automatically come on when needed and top up the water temp. With timers you start getting drops in water temps depending on weather and when the pump comes on it has to work extra hard to warm things up again.
I installed an immersun ( the old co that went bust ) in 2009. It has produced nearly 9000kw so far. I am just applying to export having added more panels and your calculator shows a £28 pa saving. As the cost of the immersun is now effectively zero it is a simple trade off with my wife preferring constant hot water at all times to having to turn on the gas. When the Immersun dies I won't replace it but meanwhile comfort at a cost of £28pa is the winner
I have been using an Eddi for a year now and find i use it as a water heater in the summer and the second output goes to a heater in winter as i can heat my cylinder on Octopus Go. Having the relay board also means we can get an idea of our water temp. Its also useful for its energy monitoring function which combined with a Zappi means i consume 90% of my generation without a home battery.
Hi Gary, just for the record, I came from Jim's channel as I have started looking into EVs. I live on a small holding so have the possibility of installing more panels than I actually need. I know there is a break even wait but have you looked into whether going for overkill and installing more panels than you actually need purely to export? I'm wondering whether it would be a good investment?
Welcome! 😀 So, for anyone adding solar panels to their property for the first time, I’d always recommend maxing out the number of panels given the one-time installation costs (scaffolding etc.) I’d suggest the same for anyone adding panels to an existing installation, but the cost of installation against the expected generation of the new panels might not justify the investment.
Hi Gary, excellent Chanel and great advice. Could I enquire about a 3 phase solar PV setup with the Eddi diverter and battery storage. Is that possible?
Hi Amjad, thanks for taking the time to comment and also the great feedback :-) Now, I don't know the answer wrt 3-phase but perhaps others can comment...
I use a SOLAR iBOOST+ to divert any surpus and this is to my water cylinder but when heating it stops it goes to a second channel which is a 3kw storage heater in the lounge so is warmed up ready for the evening period, During the winter time the Storage heater is charged up on the GO tariff 00.30 to 04.30 am as I have a EV Car
For those of us on the old feed in tariff who are paid the same irrespective of how the electricity is used using a solar diverter (or indeed a battery system) to use the excess electricity makes sense. What was not fully analysed was the cost effectiveness of the other schemes. The diverter was targeted as the bad boy without full comparison with the other options.
Hi Ralph - thanks for taking the time to comment. The trouble with government incentives like FiT, is that it distorts the market (usually for all the right reasons, but a distortion none-the-less). As FiT is no longer available to anyone, and the solar market is really only just getting started in the UK, it should not be used as a metric to prove the diverter use case. And in my video, I could not prove the case myself, as much as I really wanted to do so :-/
The thing here is that the share of energy production varies during the day and the export price does too. So the hours when you have excess solar are the same when everyone else has. That means you get almost nothing for exporting moneywise and around those hours production is close to 100% renewable anyway (at least where I live). Even then, I agree that is not worth all the investment on the diverter just to heat water
For the tariffs in the UK, the export rates are fixed for certain times in the day - they don't vary depending on renewables production in the country. But it sounds like that where you live, they do? What is a typical percentage of solar production against overall demand? Here in the UK, it's less than 5% (although wind is sometimes >50%)
@@GaryDoesSolar Here we have a different rate each hour and is set the previous day according to expected demand and weather. Most days is 20% wind and 5% solar
Thanks Samu - it's good to hear about how tariffs work in different countries. This sounds very similar to the "Octopus Agile" tariff here in the UK - which is not for everyone, but could become more popular over time.
Hi Wayne, true. I tend not to talk about FiT as this is a closed scheme now, as those on it are generally still onto a good thing. It was designed to kick-start the consumer market, and it seems to have worked well. I'm wondering though if rising export tariffs get to a point where even FiT is no longer the best way? What I mean is, for those on FiT say 5-10 years ago, they may be better off upgrading their panels (perhaps doubling array size)...?
@@GaryDoesSolar Another great video Gary I understand your point, but it really depends on your set up beyond the pv system itself? For example, as well at an EDDI, I have a Zappi and 17.5 kwh battery and an EV. The FIT scheme assumes 50% of what I have generated goes back to the grid. In reality, I export now less than 5% back to the grid, plus you still get paid for each KWh you generate. Those are worth approximately £750 p.a. (3.9 kwh) in cash back. If you upgrade your array to anything above your original size then the FIT payments stop (you can replace like for like). Undoubtedly, there will be a point at which the size of the array would be beneficial but at what cost and what size? Given most are on either the 20 year payment or in my case the 25 year payment scheme , I imagine would have to at least double the size of their array which in itself is likely to require a further £10,000 investment. I would therefore suggest that you are correct on an solar diverter for those on SEG payments but possibly not for those on FIT payments.
@@SimonFranklin-wr9yu Thanks for the kind words. And you've just shown me just how good the FiT scheme is - wow! Very hard for a SEG scheme to compete! 😳😀
Really interesting angle, i hadn't considered exporting as a means of reducing somebody else's carbon footprint. On the energy mix, i think you're more likely to be biased away from the fossil fuel generators as solar produces best in sunshine which is when fossil fuels are alost least likely required (i.e. during the day on bright conditions when least likely for high electricity use)
Hi Bob, yeah - I really struggled with trying to figure out what happened with that 1kWh of export! Take a look at my pinned comment - I'm convinced it replaces marginal generation, but I'm sure that's all up for debate still!
The other thing to consider in your example is that the water heater is a resistive element and therefore 'losses' are lower. The neighbours vacuum cleaner uses a motor which may have a power factor of '0.6' since you are powering a motor - this will vary with brand. On a 1kw vacuum cleaner the neighbour only pays for 1kw, but the power company is supplying approx. 1.6kw - thus 0.6kw 'wasted'. This is a prominent issue with battery generators such as EcoFlow which seem to not last as long. It will provide power during a blackout - but inefficiently for many household products (Laptop - 0.41pf), freezer (0.5pf). Thus don't buy these products in the hope of charging at night at the cheap rate to power equipment during the peak rate day - you will be disappointed!, since like the power companies the EcoFlow is supplying the power factor losses. Industrial companies running motors pay for the pf losses, but residents don't.
Good points - I guess was just considering the actual power (1kWh) that the neighbour would be billed for, regardless of how they used that. After all, they may choose to use a resistive heater instead of a vacuum cleaner?
@@GaryDoesSolar Firms like EcoFlow advertise their equipment for powering electronic equipment within the home during a power-cut. Yes it will do that but what's missing in the fine print is the effect of power factor. A tradesman working on site will add up the power of his power tools, and the time spent using them during the day, and choose what they think is a suitable generator only to find they run out of power by lunchtime. No fine-print to try and educate them - so the tradesman ends up have to buy a plug-in battery pack. So my comment is trying to educate people since EcoFlow don't.
However being on FITs we don't get any more money if our electricity is exported. For us it makes much more sense financially to divert the excess into our thermal store tank. Another 13 years till our fits end.
For me the calculations & logic of this presentation are most interesting; however I beg to differ. Why? I've had solar PV since October 2011 & two of the old style Immersun power diverters that I self-installed purchased in 2012 (new - master) & 2013 (used/much cheaper £50 - slave). The extra solar panels are rated at well above 4.0kwp but are limited down by a 4kwp Sunny Boy inverter. Payback was exactly 5-years for the basic system. The house has no gas supply or open fire or wood-burner; it's all electric. The two Immersuns are part hard-wired & part wired via switches & normal 3-pin sockets, but always on a separate circuit away from the mains supply. The Immersuns heat my immersion tank, 7-litre shower reservoir tank, 2x very old storage radiators, kettles for hot drinks, oven for baking & occasionally a 2-ring thermostatically limited mini-cooker. I manage the power-switching via rotation, as & when needed. NB. You can't use Immersun pulse power to power anything that has transformers, electronics, motors, inside; they'll be damaged. Output is currently in excess of 5,000 kwh pa & receiving around £3,000 pa in total FIT receipts, (not from Octopus, but I'll consider the merits of Octopus later, although I didn't like their T&Cs small-print last time). My electricity import bills from Utilita are less than £100 pa (zero standing charge), & they even gave me £400 over the last 6-months as a general grant (6x+ years of supply free). Original budget was 20.4% IRR, but even with the costs of the extra below, I'm running at 15.4% better than budget. Currently self-installing an upgrade with a Sunny Island hybrid inverter & 4x massive AGM batteries, with a MyEnergi Eddie (only £390, as the new hybrid inverter won't talk nicely with the old Immersun units - shame). Add a further year to payback for these extras. I think that IF anyone has gas-supply, a BIG lithium battery (maybe Tesla powerwall?) & Octopus export tariff receipts, then your reasoning stacks-up well. If anyone's interested, my data is on the website of PVoutput.org & search for JohnnyK's-PV; I'm in the UK. I'd recommend solar PV in almost any guise; it makes so much sense. Keep-up your videos Gary; they are interesting.
Thanks for taking the time to comment, John. I'm not sure I understand where/why you disagree with my reasoning in the video though. Can you explain, because if I want my videos to be accurate. Many thanks!
@@GaryDoesSolar Hi, I'm guessing that your reasoning is correct for the vast majority of normal people. However I am not an average person in an average household & choose to live the life of a 'green-nutter' - lol. Just taken a look at the two links that you have of Octopus Flux tariff & your calculator. First I don't have a smart meter & even if I wanted one, my electricity company will not fit one, as I have a 3-phase supply & use economy 7 tariff. Tried 3x times in past years, they won't fit one, but now I would choose not to have one anyway. The export rate offered of 25.26p/kwh sounds great though, as I currently only get 4.25p/kwh, but that is mitigated enormously by my FIT generation rate received of 60.23p/kwh. Also I currently have a Utilita smart tariff (even though I don't have a smart meter). There is zero standing charge; that is recouped via a mega expensive 90.32p/kwh + 5% vat of a day rate. The big but, is that I use so very little on day rate import that my annual bill is currently estimated at £25.93 pa (yes.... I didn't look-up the exact figures in my original comment when I stated that my house used
@@GaryDoesSolar Although I've limited my comments to the subject material of your video & therefore of the economics of solar, diverters, battery, etc. my main interest is in trying very hard to live a more sustainable lifestyle. I actually put more time & effort into using as little as is reasonably possible of energy, food, water, fuel for my car, & growing/foraging food for personal consumption. Most people might describe it as an alternative/frugal lifestyle (if they're being nice to me), however the economics really do add-up & I can save significant sums of dosh even on a very low p/t income. I'm also living the F.I.R.E. lifestyle for real.
This is interesting and is worth the watch if only to make you think. BUT isn’t the point of the diverter that you can tell it what to do and when? So a mixergy tank could be controlled by it’s own controller to warm only what is needed, learn the families patterns, save water AND you can set tariff thresholds decide IF you want solar involved or not, use a boiler and/or mains, plug in a heat pump and this all makes your calculations different again. BUT I thought you got the EDDI for example so you could do this and change your mind for when export tariffs like this are high, but change it back if they drop again.
Hi Jeremy, I love it that data is becoming more and more the foundation of how our systems will work in the future, rather than just basic logic. Your comment is a great example of how we can use data in this way :-)
Really interesting video. As I have an EV and a PHEV to charge, Octopus Go works better for me than either of the export tariffs. That means I’ll get just 4.1p for any exported electricity. The environmental point is a fair one, but I’m not sure. How far do we go with this, in summer do I get my neighbour to plug in his mower to my house to use my solar so that he isn’t using grid electricity? And do we have to check how much wind and solar the grid is receiving at the point of deciding? If it’s particularly sunny and windy, then the grid will be very green
Hi Billy - yeah, hopefully we don't have to go too far with such management :-) I think we just need to continually move toward lowering the percentage of fossil fuels in the mix...
Hi Mate Thanks for the video. I’m from Australia and here for example I pay 45 cents per kilowatt and if I don’t use all the power it gets sold back to the company for 5 cents per kilowatt … So unfortunately here in Australia the only people making money are the power companies. So it costs me 45 cents to buy and then they get it back for 5 cents !!!. So in your Opinion and experience is this worth me getting the Solar diverter ??, I gathered it was due to how much the electric company gets back compared to the customer!!.. Cheers Mate look forward to your reply …
im in northern ireland and since the start (1st nov 22) of the EPG government help kicked in i have been exporting everything i can and plus a bit extra from my batteries. before oct 22 the export rate was £0.0785 then and then after that it has jumped up to £0.1766. then plus with the EPG help the night rate went to £0.0158 import for a month (all november) then it went to £0.047 and it still there until the end of march 22. so i heat water at night, charge the car at night on eco7 (winter 1am-8am / summer 2am-9am) and export all the solar i can and i have also exported a bit from my battery every night too just to help
Hi Stephen, sounds like you've got a great strategy there. I love it that higher export rates are causing us all to re-plan what we do with out energy generation.
I have a fit tariff {another 10 years left) and I'm credited with export calculated on my generation so If I export everything I make i'm only credited with half the generation. Subsequently if I use everything I make I'm still credited with a 50% export of my total generation even though I dont export a thing. So a diverter turns my water tank into a solar battery and I get to keep as much as I can of what I make. A battery would be great but without the initial high cost this is the best I can make of my 4kw system, which after 10 years has now paid for itself. When there's a decent amount of good sunshine I turn my hot water boiler off. I purchased my iboost for less than £300 and fitted it myself and its paid for itself over the 4 years I've had it.
Hi Chris - that’s brilliant. Yeah, you’re very fortunate being on the FiT tariff. For the rest of us, a Solar diverter might not make as much sense unfortunately.
You need 1.25kWh gas from your boiler in your example with an 80% efficient boiler, not 1.2kWh. The argument is still well presented, and now imagine you have a heat pump with a COP of 3, 4 or even better. Someone needs to come up with heatpump controls that recognise excess solar production
I am interested if you using a Air source heat pump running at SCOP of say 4. Surely it makes more sense to use that to heat your hot water. Rather than using solar diverter to heat the hot water tank at a much lower efficiency?
I don't know too much about ASHP for water heating yet, but I agree - they should be much more efficient than diverters. I'll be researching into this before long...
Hi Gary, great video and has made me consider the use of our Eddie which we had installed last year. I have always felt heating the water with our solar instead of the boiler is a huge plus, but now I’m reconsidering. I will say it was a huge benefit having the programmable timer on the Eddie when our boiler failed last winter! Would the diverter make more sense in a house without a gas boiler? We intended to have our boiler swapped out for a Tepeo ZEB and with our induction hob won’t need gas any more. Once capped off we will save on the standing charge each month so would that not offset the cost of the diverter? When the day comes we’re all banned from buying gas boilers in the future, diverters a have a place again don’t they?
@@GaryDoesSolar That may be an interesting cost/benefit comparison to do as more people are having heat pumps installed. A friend of mine is building a new house and with new regulations is basically being forced down the heat pump route. I guess if you have a heat pump running from your solar is it any different to having the diverter? I guess that’s the same for a Zero Emission Boiler. If I charge the boiler from the solar, then it’s the same job the diverter is doing. Adding another step to the process but essentially the same.
@@amcarvids5094 What make the heat pump more effective than a diverter is the fact that you put in 1kW of (electricity) energy in and you get 3-4x (heat) energy out. A solar diverter is just 1:1
Setting up your solar based on exporting to the grid is an inherently fouled design approach. First, it totally exposes you to the fluctuations of pricing, government policy or energy market. Second, you cannot make anything more energy efficient than using energy at the point of generation at the time of generation, directly. Just because at this moment you temporarily can make more money out of it does not mean you make a wise decision. In my country (and in a lot of others) it's not just that they dropped the export price but explicitly prohibited exporting because the large renewable ratio starts causing issue in some subnets and it would take several years of GDP to completely rebuild the eletrical distribution system. Renewable energy: use it when you have it and where you have it for something you actually need. Whatever formulas or arguments you bring up it can be measured against this as a golden standard. If the result is that you should export energy and then buy it back because it makes more sense you know your argument is flawed.
Surely we have all had enough of Grid Tie systems, we have seen the greedy energy giants for the crooks they are, making excess profits and using the blood shed in Ukraine as an excuse to ramp up prices. OFF GRID is the way forward.
@@richardsandwell2285 from where I see it power grid is a valuable service and irreplaceable in a lot of places. Residental homes are not those places. Single family homes today are in a great position to generate a good chunk of their power need and still use grids for backup so you don't need to mine entire South America for lithium. Grid companies should participate in this but probably not as the Great Sources of Energy, instead as real distributors and organizers. Our homes should use grid but not exclusively and not to a very high extent. This would also handle the issue you mentioned that they are not too much in a power position - both figurative and literal.
Hi Kobor, each country is different. In general, I believe exporting energy is a good thing, because it means less marginal fossil fuels being burned. And if you can get paid for that, even better. My own installation is designed to be as flexible as possible, in order to benefit from fluctuations in pricing and also higher export rates. I don’t view this as a ‘fouled’ approach at all.
Not sure I fully agree with the thinking process. The scenarios assumes that excess solar exported to the grid will be used at the time exported. If it is a sunny day as described, then there must also be other solar households as well as solar farms generating excess energy and no guarantee all surplus will be consumed by other users on the grid. If there is a surplus on the grid then what happens (stored as hydro, curtailment etc)?
I would say it’s extremely unlikely your exported energy would make it past the substation. They are far more people without solar and home battery than with…
@@GaryDoesSolar I haven’t read the studies and so am shaky in the matter. If we use export payment as an example and indicator of demand, and today’s Octopus Agile export price (09/06/24), it ranges from 0.59 pence to 2.45 pence between 11:00 and 15:00. Does a low actively tracked export price not indicate a lack of/reduced grid demand?
@@georgechirayus4865 I would say that any time the price goes low, it's not an indicator of reduced demand, but instead an indicator of over-supply (typically wind and solar). But remember, in the UK, solar at most is only 10% of the supply mix (it is growing though year on year) and I'll be talking about the macro effects in a video I'm working on... In relation to your original question, take a look at my pinned comment to the video, which is my view. It's great to debate that though - always happy to be proved wrong! 🙂
It's a good job I didn't do it based on a payback calculation rather than just wanting to worry less about running out of hot water - our tank is slightly undersized for our needs due to size of the property (i.e. the physical space available for the tank). I agree that it does lower my contribution to a greener grid, but the trouble is when I've got lots of export available there's a good chance the grid doesn't need it anyway. ...but to make sure my battery has priority my diverter ignores 250w export. So when I'm charging water I *am* still contributing slightly. If the whole street was doing that, that's still several kw leaving or being used locally on the estate. If folk were all generating and using locally, the grid would be greener and less spike dependent in general. I'm going to worry about my grid contribution once I see signs that grid scale storage is properly happening. Then there'll be an unarguable serious communal good argument. Till then I'm in your top row: 4p export, import 12/40 on octopus go, and we have high water usage compared to our tank size.
In the UK were at between 40-70% gas for electricity, depending on the weather, time of day, and season. Generally this averages out at just less that 50%, and falling. Of that, 50% is imported (therefore about 20% of the total) and therefore higher carbon footprint than the other 50%. Coal is now a tiny fraction. Biomass is I think 10%, argue over it's footprint if you want. The point is, between about 50-70% of our grid in the uk is already renewable, depending on season, time of day etc., And of the rest the bulk is gas which is at least cleaner than any other fossil fuel, or nuclear and biomass. Some peaker usage is hydro the rest is gas or coal in mid winter. If we had proper grid storage, we could kill off those coal and gas peakers at the very least, and reduce the dependency on the base load generators. So in the UK it really is purely a monetary thing - how good is your export. The environmental argument of making your own hot water does make sense. Arguably in winter it is more socially responsible to export. Regards grid storage don't get me wrong for all this to work we need at least 12 hours of high response and several days if not a week's worth of slow response. Expensive: but with the right mix of even current storage tech at varying scales, entirely doable.
Its good news that SEG rates are increasing, but trying to get registered with Scottish Power is a nightmare. I’m an Economy 7 import customer with Scottish Power, which you would think would make life easier (as they have all my details). 5 months after submitting the SEG paperwork and many, many emails chasing up, I’m still waiting!
Sorry to hear this, Dave - and I hope they get it sorted soon. If you have a Twitter account, express your frustration on that and I'm pretty sure your SEG will be addressed soon after...
Your financial argument is fine at the moment because the better export rates are available because of the high cost of energy from providers. Those rates will drop off a fair amount when normal regular electricity is back in the 20-25p margin.
@Gary Does Solar so say we all! Our business rate is 72p come the start of April, just glad most of our usage is in the winter to drive the heat pumps with the business support and then solar picks up the the strain around April anyway. We're having 6kw pv and a 9.5 battery installed on our house in a month so I'm looking forward to getting a tariff sorted. While the export rates are high I'd be tempted to set an Eddi to do nothing unless ones export was up near the export limit of 3.68kw (say 3kw) and then turn on. That would earn the better export rate and prevent the inverter having to limit its export to stay under the cap. As rates fall again, it's easy to change the setting.
@@MrDBT85 Wow, business rates are just crazy, eh?! But it sounds like you're doing all the right things to compensate. I like your thinking about usage management, and I wish you the very best this year! 🙂
The rising price of selling solar to the grid is totally or at least partially offset by the higher prices of gas and oil used to heat the water instead - or did I miss that this was taken into account?
Yeah, this should all be in balance with each other - everything should be based on wholesale prices. What we've seen (at least in the UK) though is that rising export rates have lagged rising wholesale prices.
The recently introduced octopus flux tariff is a game changer. For the months one is net exporter of electricity it is easy to set and pays good export rates. Probably the Agile export will pay a bit more, but takes time to check daily the rates
Hi Gary, interesting stuff, thanks! I'm just about to make my decision whether to buy and install a diverter for my newly installed plant here in Switzerland. How comes you assume that every exported kWh is available for consumption by others? Isn't there way too much energy around in the grid anyway during a very sunny day which cannot be stored by the provider?
You're most welcome, Martin :-) Your question is a good one. I'd answer by saying that your exported energy will likely never make it past the substation back onto the grid. That means it will be consumed by a neighbouring house, because there will always be a draw from the grid at any substation - even on a sunny day.
@@GaryDoesSolar to follow that up, yea, when you export from one house, it simply reduces the import rate at the substation for the neighbourhood, so the grid operator has to turn down generation going there (a tiny tiny bit) usually by turning down the gas or offering it to balancing services.
Thanks, very interesting discussion. Not applicable for me as I have a Combi and the cylinder was removed a few years ago. I can just about manage to use all my solar with my EV , battery and other heavy usage devices. Never export anything from October through to April, over Summer only about 300 Kwh exported equivalent to £12 on SEG.
Thanks John for the kind words, and also for taking the time to say a little about your own situation. They certainly say that the best way is to consume as much self-generation as you can and by the sounds of it, you're achieving that :-)
I have a combi and a tank. I can pre heat the water so that the combi doesn't fire up. That said, I don't do it at the moment as the payments from the export are more than it would cost to heat the water using the combi. Where the tank does come into its own is in the winter on Agile. Price drops can then pay me to heat the water.
Hi Kier, so the utility I developed is designed for gas, but I believe you could enter appropriate figures for oil/LPG. I’d be interested to hear from those who might have done this 👍🏻
Unless you build in a limited life-span for the inverter, it is counter to logic that you cannot get your money back eventually, if the cost of importing remains greater than the price received for feeding into the grid. Your assertion does work IF you assume an alternative source of heat (gas) at a price of 13p per kW. Your theory re environmental impact becomes less cut and dry if you take into account the likely-hood that on those days when we have excess solar power to export, the grid will tend to be awash with green solar generated power. Especially on days which are both windy and sunny. As solar and wind farms increase, the more this will be the case. But excellent food for thought.
Yes, but how long is eventually? I show in my video that eventually might be decades... On the environmental impact, solar today is < 5% of the national UK energy mix, therefore minimal impact on the numbers. You're right about wind - there are certainly days when it is above 50% of the mix, but my utility looks at a whole year, which is a more accurate basis for the numbers. I agree, as wind and solar production increases nationally, the requirement for gas reduces and so the impact is ever smaller - I can live with that, given how much better things will be for everyone.
Could you not just use a timer switch on your immersion heater to heat the water at the time of the most solar power generation, at a fraction of the cost of one of these diverters?
The aim is to only use excess solar for your hot water. With a timer, if it’s not been a great day for generating, your immersion may well take all the electricity you need to charge up your batteries, leaving you on grid electricity that evening. The advantage of the diverter is that you get to use your solar, or store it in a battery or EV before it heats your hot water
You can, but the eddi will divert whatever the excess is. So if you have a 500w excess it will only send 500w to the tank. Other methods that simply turn on your 3kw immersion when there is say 2 or 3kw excess still allow a lot of energy to be pissed away. For us on FIT it makes sense to use the eddi as we're getting paid for it whether we use it or not.
I am thinking I wasted some money on my iBoost. I am very happy with the rest of my installation. It was installed in December and I already surprised how much I generate on a good sunny day. I have also noticed the sun is getting stronger. The issue I have seen with my iBoost, twice, it has flattened my battery. For some reason it kicked in and then the battery kept it kicked in. I have upped the watt limit to try and stop it.
That does sound like a problem, Michael. Get onto one of the many solar forums and ask for advise. I’d imagine you’re not the only one with those issues…
I actually came to the same conclusion about solar diverters when considering Octopus Flux. It's actually worse when you consider a heat pump which normally heats DHW at night at the cheap rate. If you divert and heat the water over the normal temperature your heat pump won't bother heating at the allotted time because the water is already hot. But consider the efficiencies - the ASHP might heat DHW with a COP of three so only uses 1/3 of the electrical energy of your divert for the same temperature rise. So using divert only saves you 1/3 the kWh of what you might think and you are only saving against the cheap rate of electricity - not peak rate when the divert happens during the day. And of course as you say, a decent export tariff blows the point of diverting anyway. The Eddie needs a new purpose!
Agreed, John. And actually, I think more and more people are seeing heat pumps coming into their own now... the world is slowly changing in that respect :-)
I imagine that in the next few years we will see ecosystems that will do essentially all of this work for you (not to belittle your fantastic work). Your standard punter wants one thing - lower bills. They don't really care how that is done
Thanks Nick - and I think you're right. These systems must eventually be automatic (reporting only issues), and perhaps even integrated directly into your energy bills...
Hi Gary, I’m about to have the Eddi installed and it’s a bit too late now but this video has brought up a point. I’m getting installed a 6.72kw system/16 panels with a 5.5kw inverter. I’ve only just been told I’ve actually got space for 4 more panels which would take the system size to 8.4kw, should I still take another 4 panels despite the inverter size since the current pay back from exporting is good? Ideally I’d need an 8kw inverter to use all that energy myself and there’s no guarantee my DNO will approve a 8kw inverter. (5.5kw inverter has already been approved)
Hi Brian, thanks for taking the time to comment. I've never heard anyone say they wish they had less panels, but I hear people all the time saying they wished they had put more panels up there... In terms of the financial benefit to you of putting extra panels up there, feel free try different scenarios in the utility provided with my video here: ua-cam.com/video/FvjuJQZRrvA/v-deo.html - this should help in your decision-making. I'd love to know what you decide to do in the end... :-)
Get the extra panels for sure, it makes sense to oversize the array anyway. I’m probably going to get a solar hot water diverter too but am aware it doesn’t currently make financial sense currently. Probably going to because you cannot predict what the tariffs will be in 5-10 years, and getting it now is vat free and inflation is rampant.
Thanks Gary & Richard, yes I’m still getting the Eddi as they gave it to me as a price match. I’ve spoken to my solar provider and they said I would have to change my 5.5kw inverter to a 8kw inverter to manage the load and I’d have to get the DNO approval again and there’s no guarantee it’d be approved and they’re ready to fit it now even though the weather have delayed them fitting the panels and the other kit I’m getting. I don’t know whether to say I’ll wait for the approval but now they’re inflating the price on the extra panels and inverter.
@@arnielegend Now, is your inverter a hybrid one? If it was, then even though it could only output 5.5kW, it can still charge a DC-coupled battery with any solar generation in excess of that (a great benefit of a hybrid inverter). Irrespective, even if your current inverter cannot be changed (due to G99) it is still worth considering the extra panels because in the winter months, those extra panels will help increase your generation (remembering that you won't be getting anywhere near the 5.5kW limit in those months). The only question then is can your inverter support the extra array size? Questions to ask your installer, I guess...
@@GaryDoesSolar thanks again. The inverter & 2x batteries are Sunsynk. The inverter is an Hybrid one. The company that’s supplying me said with the 4 extra panels it’d make the an 8.4kw system and said the 5.5kw inverter wouldn’t be able to manage the load and would need an 8kw inverter which they don’t seem keen on supplying for me unless I was to push for it.
@@GaryDoesSolar Thanks! For a family of 3, $1700 total investment cost, $0.26 kWh imports and $0.04kWh exports (I don’t have gas), you tool estimates that it takes 24 years to recover my initial investment!!! This is crazy long. What assumptions go into your model? Thanks again for making this available.
@@DanielG0m3z The calculations should hopefully be self-explanatory but if I get time, I'll add further detail on those. Great that it's save you making a bad investment.
I guess most power plants - at least in Denmark - would also utilize the heat that is generated when generating the electricity, so burning gas just to get heat is probably not the best way to utilize gas.
We're on a deemed export so all power we generate Is 'paid for'. On an annual average we divert 2.5kwh per day into the tank so in summer virtually zero gas and zero grid for hot water..
@Gary Does Solar yep the system went in Jul '15 14×250W on two roof pitches 6SW and 8SE all on Enphase micros. . with an i-Boost diverter unit . Then panels peak at about 2kW-2.5kW and average 10kWh/day over the year, but because the panels are on the two pitches the bell curve for generation covers a wide spread of the day. The house only needs about 400w base for fridges internet stuff Alexa chargers etc.. our current net feed in from Ovo is about 19p/kW generated.. in hindsight an absolute no brainer
I'm using Oil to heat my Water has there's no Gas in my Village, since getting a myenergi Eddi fitted 3 months ago I've only used my boiler twice on Dull day's the other day's my Solar Array has given me Hot Water, I'm very pleased I had my Solar Diverter fitted 😍even though I'm on Agile Outgoing Octopus. 🤦♂
This assumes you have access to and are using gas, in an all electric house the sum will change. I have an Eddi > Sunamp + Storage heater. I have no access to gas. Eddi pays back in a year.
I am interested in Octopus' Agile account but I am still waiting to install my PV / Battery system. Should I wait until that is installed before switching as the online quote I got is not for Agile?
I think Octopus require all sorts of details about your installation (include an MCS certificate?) before they'll switch you to that. Best to wait until everything is in place, I reckon. Hope it all goes well for you though :-)
@@GaryDoesSolar I did look at it. I still believe Agile is cheaper. Flux obviously removes the risk. It February I saved £26 by being on Agile over the standard 35p rate. I charged the batteries overnight with 4 slots. February was a good solar month. So far March has been a shocker 😀
Surprised you didn't mention just heating the immersion in the middle of the night when electricity demands are low and rates are cheap. If you are on a tariff with octopus anyway I would assume they have cheap rates in the middle of the night, so you could export 1kWh of solar at say 14p and then import it back at 7p at 2am (I don't know their exact rates). That way your solar export is used during the day when demand is high and the import is done during the night when demand is low so is likely from nuclear or wind generation.
Good point - would have been a nice segment in the video too. One issue I see though is that off-peak tariffs are not as attractive as they were a year ago either. And generally, heating by electricity is more expensive kWh per kWh than gas. Let me run some numbers to see if there is still a case to be made - thanks! :-)
@@GaryDoesSolar Yeah I just had a quick look at rates and not sure it would work. I'm in Ireland where gas is current 13c ish per kWh, kerosene which I'm on is about 10.5c, and my electricity is 9c for 3 hours overnight. So with the efficiency loss on boiler it is cheaper (by a small bit) to heat with electric overnight. And it should be more environmentally friendly as overnight should be using wind generation a lot of time. But it still is marginal enough difference that its not fully clear cut. I had thought you would have better night rates on offer as I know economy 7/10 used to be quite popular but from quick look not sure be worth it. The other thing I was thinking was the eddi is quite expensive and I think a smart switch connected to home assistant could do the same job for a lot less. You would have to be careful about which switch due to high power. But something like a sonoff powr3 has 25A limit, or could use a smaller switch a contactor to be extra sure.
@@gillo100 Another factor to consider is solar adoption rates. As more people go solar, the peak demand will shift steadily to the nighttime and make that power more expensive.
@@notbatman1001 Yeah, will be interesting to see how things develop. The 'nighttime bathtub' is pretty deep though and will take a lot to fill it... so I'm hoping that there will always be a differential in pricing between day and night.
I'm still on a feed in tarrif at 5p per kwh so I guess it depends on how long these decent export rates would continue for. Presumably I'd have to give up fit to get new export rates?
@@GaryDoesSolar you can continue on your FIT generation rate. You get paid for your generation by your FIT supplier still. It’s the 50% deemed export under the FIT scheme that you lose. Quite what happens if you swap your deemed export to one of the current export schemes instead and then want to go back later I don’t know. There has been nothing about that so I can only guess and say you cannot. So be certain when or if you decide to trade your FIT deemed export for a new export tariff that you are doing the right thing.
@@GaryDoesSolar my pleasure Some further information about the FIT scheme. The payments were guaranteed for 25 years, they are updated every year and increase in line with inflation. Last year our own generation rate was 60.23p per kWh generated and the deemed export 4.25p per KWH. We expect a letter in the next few days letting us know the new rates but as it’s the same figure as the pension increase it will be 10%. As you say elsewhere the FIT scheme was designed to prompt domestic solar installs and we feel very fortunate to have got one of the last full fat rates in 2012. After April 2012 the FIT rates were gradually decreased until the SEG scheme superseded it.
@@GaryDoesSolar thanks Gary. Great channel by the way and the only source of concise accurate advice I have found all in one place. Having spent many years learning about it myself. Cheers 👍
Solar diverters work when the sun is shining (obviously) and that is mostly during off peak times. This is also the time that the country's energy mix is extremely green so I am very skeptical regarding your argument that not exporting your solar will lead to higher emissions. In fact the opposite is far more likely, if you export during off peak times and then use gas to heat your boiler during peak times just before using the hot water then this gas is likely to be the dirtiest.
The logic makes sense but something bugs me about the argument. I realised it's the same argument put forward at the start of the electrification revolution and adoption of EV's. People did (and do) argue that powering high powered electrical items like EV's are worse for the environment as the electricity comes mainly from dirty coal or gas which is then inefficiently transported over wires to your home or to power a train for example. They claimed it was much better to burn petrol at the point of use. This argument is somewhat valid if the electricity mix is very dirty but of course it neglects to take into account that the electricity mix is ever changing and becoming cleaner. The best way to incentivize government's and be zero carbon ready is to electrify everything first, the energy mix will be cleaned up after. If we wait for the mix to become 100% renewable first before removing gas boilers then we'll never kick the burning habit.
@@GaryDoesSolar No, if you're evaluating the impact of the installation choosing to heat water instead of exporting, you need to look at the mix at the time the decision is made. Personally, I'm not convinced a diverter is much use without seasonal thermal storage.
@@jocramkrispy305 That's a good point. The problem though, is that solar diverters have the capability to monitor instantaneous energy mix (as far as I am aware?)
Great video thanks Gary. 😎 You’ve confirmed (with science) what I’ve been thinking about my iBoost diverter since I went onto the Octopus Flux tariff last month. The news about the carbon cost of generating the electricity we don’t export to the grid was a real eye opener. 🫣 My current strategy is fill my battery with as much power as it will take from 02:00 to 05:00 and get exporting as early in the day as possible. I’ll see how that turns out over the next couple of weeks. 🤞🏻Cheers. Mark
Hi Mark, loving the Max Headroom profile pic - takes me back to my college days! Happy to have helped you out - it's such a shame that diverters aren't worth it, as conceptually, they're a great idea! I like your strategy and I think you'll do well with it - my strategy will be the same, just as soon as I get my export MPAN :-)
Thanks Gary - I’ve just run the numbers for last week and the strategy not only paid for the electricity I imported but ALSO the gas 😎 If it wasn’t for the (insert curse of choice here) standing charges, I’d have made a £2 profit !! Octopus are really enabling micro generation and when it comes to setting you up for exporting they don’t drag their heals so I hope you can start to enjoy the benefits of Octopus Flux very soon too. Please keep up the great work you’re putting into this channel chap. 👍🏻 VBR&T Mark
@@Bushmaster101Green Yeah, the level of standing charges today is just crazy - particularly for those who don't use much energy - they're being penalised far more than anyone else. I'd much rather the standing charge was reduced to only that to cover the cost of the infrastructure, then the remaining items added to the variable costs (just like many other costs are today). Great to see you're now saving (and hopefully soon earning) plenty cash - I'm just waiting for the G99 certificate to come back from SSEN then I can sort my export MPAN 🙂
I agree the burden of the faux carbon neutral agenda is going to be borne on the shoulders of the least able to pay for it. To quote Guns and Roses - ‘it feeds the rich, whilst it buries the poor…’ who can’t possibly afford solar, EVs, heat pumps, ground source or wind generation… 🙄
Challenge I have is that Intelligent Octopus is a no brainer if you have a EV, Solar and Battery (7.5 6 hours cheap rate vs 20p for 3), but the outgoing octopus rates can't be used with those. There seems to be a gap for folk who uses Intelligent or Go but who could export more.
Yeah, many people say it's to allow Octopus to derive some kind of revenue from Go and IO customers, but I agree; I don't see why a relatively healthy export rate could not be added to those tariffs...
Another interesting video Gary. Thanks for this, really valuable. Hoping I can follow in your footsteps with some of my videos about my solar install on my channel. Just starting out but can hopefully help a few people out like you are doing. 👍
Hi Dan, you're most welcome! I took a look at your channel and I really like it (have also subscribed) - good luck with your UA-cam journey - hard work, but well worth it :-)
Thanks, Gary. You are providing a useful service.
I went solar from late 2021, including a year ago replacing my 30 year old gas-fired HWC with a 2-element one, controlled by an Eddi, as part of a MyEnergi suite. I had to wait more than a year for Zappi to be approved for use here in New Zealand, but that's another story.
For me the addition of the Eddi was a no-brainer. My electricity provider offers 3 hours of FREE power for EV owners between 9pm and midnight. So I was already charging my Powerwall nightly and my EV once or twice weekly on this plan, and not keen on my summer surplus to the grid earning me peanuts.
Now throughout the year, with the Eddi added, I top up the HWC every night for free. And with excess solar generation in summer that means all its hot water is leading towards my payback date, and in winter I just need a single 1-hour midday boost from the grid. And I can feel good about that free power being from NZ's hydroelectric generation...
Thanks for sharing this Ed - really useful insight, and I love the fact that you're getting free power at certainly times in the day - wow! If only we had more (and the right kind of) mountains here in the UK...!
Very interesting stuff, Gary, as always. Something I'm considering doing is using my eddi as a (very expensive) timer to heat my hot water during off-peak times, rather than as a diverter. The grid carbon intensity tends to be a lot lower overnight than during the day so this would have a good positive environmental benefit as well as potentially being financially beneficial too, particularly if the export rate during the day is higher than the import rate during off-peak times (as it is for Octopus Flux). If I didn't already have an eddi a cheap £20 immersion heater timer would offer the same benefits at a much lower cost too, so that might be something for folks to consider.
Thanks Tim - and I like your thinking! The off-peak Octopus Flux rate is pretty good. And, as you say, a basic timer unit (able to handle a 3kW load and daylight savings time adjustments) would be sufficient. Do the numbers work out ok for that?
After watching this video I pulled the plug on purchasing a diverter for my new Tesla PW3 system as I'm on Octopus Flux. Thanks Gary.
You’re most welcome, Barrie - glad the video was helpful to you 👍🏻
I fitted my Eddi about 3 years ago and it's paid for itself already. At that time having a battery seemed hard to justify. How things have changed.
I now have 9kWh of battery storage (approx. cost £5k) and view my Eddi as a cheap additional 8.5kWh of storage into the hot water tank (cost approx. £400) fitted myself.
Its a nice feeling getting all your hot water from the sun for 8 months a year. Another Plus for the Eddi is the integration between Myenergi and the Agile tariff, automatically heating the hot water when a price plunge occurs below your target price (5p a kWh).
That sounds like a great setup, Pablo! And making use of plunge pricing is a real game-changer 😀
I want to fit my own water tank, I'm fairly confident in my abilities (apart from a unvented tank I'd leave that to a plumber). But worry about house insurance getting funny if I was ever to make a claim in the future and they found it was installed DIY. Thoughts?
@@ratgreen The Eddi diverter is a simple install. Can't see how it would have any effect on your home insurance.
Thanks, Gary. I will be getting my solar panels and batteries fitted in a couple of months time. I have cancelled my order for an Eddi as it was not as compatible as I would have liked with my Mixergy tank. Your excellent programme has reinforced my decision by to cancel. I will be using Octopus Flux.
Great stuff Jean, I would have liked to had a Mixenergy tank installed when my own tank failed last year, but the lead time was too long. Good luck with the Flux tariff and enjoy all that export income! 😀😀😀
This was an very interesting video @GaryDoesSolar. With regards to Mixergy, is it will worth having such a smart tank (I’m guessing, “yes”) @jeanh9641 and based on this video, I’m assuming it’s not worth having the Mixergy tank with the solar element, which is now an add on, to work off of solar (i.e export)?
Great video. My setup (panels, battery and diverter) is due to be installed in May. To me the main advantage is your basically fixing the price of your energy. Your case relies on energy companies paying that much for export into the future. I also have an ev and the flux tariff is more expensive to charge overnight. I’m still getting my head around it but I’d think I’d charge up overnight at 10p and use as much solar in the day as possible. But time will tell.
Hi Alan, thanks for kind feedback. I don't have an EV (yet) but if I did, then I'd likely be on Octopus Go. Flux is a great tariff, but it's really only suitable for those with solar and battery. Hope all goes well with your solar installation - May will be here in the blink of an eye!
Always nice to see a different perspective. The amount of home Control/Instrumentation that is being added to on grid domestic properties is mind boggling. People are almost engineering their homes. As an Instrumentation Eng. who understands it all, I would not have it in my house. It will eventually fail costing you equally or more to replace it than what you saved using it.
All this "green energy" needs to be harnessed and handled externally at a national level and the end user simple buys it in at a reasonable cost just like years ago. By all means, install a cost effective PV panels to supplement your daytime use but the rest should be transparent keeping your house simple so you can get on with your life.
You raise some really good points. And it was the primary motivation for me to make this video about the mass consumer market: ua-cam.com/video/q6t0AAi5Jws/v-deo.html
I'm not sure though that many early adopters of home solar PV can see past the way they think... Your word "transparent" is exactly it! :-)
**** On the Scenario A or Scenario B question ****
I'm now fairly convinced that Scenario A is correct. Consider the following:
1. Your 1kWh will never make past your local substation. Instead, it will quickly be grabbed by your neighbour. That means your substation draws one less kWh than it would have done. And that means the grid can reduce its supply by 1kWh. And that reduction will come from the marginal generation source (i.e. fossil fuel).
2. Forget for a moment that we're dealing with diverters, and instead imagine thousands of domestic solar installations exporting energy on a sunny day. All of that export is counted as renewable energy in the supply mix. And we know that the more renewable energy there is, the less fossil fuel burning is required.
Therefore, if you export 1kWh, you're preventing >1kWh of fossil fuel being burned to make up for that.
Does anyone see this differently?
Btw, if you enjoyed this video and would like to look deeper at the data, I recommend you watch Tim's video on solar diverters here: ua-cam.com/video/bMA2uudMgsQ/v-deo.html
This all makes sense of course unless you are on the old FIT system. Diverted is basically free hot water and still being paid for export (of course not as much as SEG)
Yeah, you can’t beat government subsidies 😀 Standard analysis doesn’t apply to those. Well done on taking the plunge when you did!
This video doesn’t appear to have a place for early adopters on the fit contracts, where exporting pays about 4p for 50% of the energy it makes. Divert to make hot water is the financial option for us.
Thank you for sharing a very enjoyable video - we don't have a solar diverter, but do have a smart relay for turning the immersion on / off depending on available solar, time of day etc - we rely on the battery as our flexible energy dump. This video has convinced me we don't need anything cleverer than that 🙂.
I suspect looking at the live grid emissions would be helpful in working out whether the gas boiler or the grid is likely to be greener. A couple of good options for comparing these are Carbon Intensity (UK only) [1] and Electricity Maps [2] - the day may significantly affect which is the better environmental option, especially given that some 'dirty' plants aren't overly responsive so the grid may turn off wind / solar on days with high renewable generation etc.
Another area to consider is the energy required to heat your hot water. We found that using the immersion heater uses roughly a third of the energy to heat a days water when compared with gas. This is partly because of boiler efficiencies and partly because the heat exchanger in the tank heats from the bottom up, so we need to heat a full tank. With an immersion, we can get away with heating the top 30% of the tank which covers our usage on most days.
[1] carbonintensity.org.uk/
[2] app.electricitymaps.com/map
Thanks for your insight here. I like your thinking! :-)
We didn’t bother with a diverter when we had our solar installed in Nov 22 because it didn’t seem to make much sense even then. I simply installed a timer and heat the water using power from the battery in the morning and evening.
The launch of the Octopus Flux tariff though seems to have really upended my assumptions of the best way to run our system. It now actually makes more sense to charge the battery from the grid during the 3hr overnight cheap rate, run the house from this during the day and export all our solar at the standard and premium rates.
Hi Stephen, I tend to agree. I'm working on a video on Octopus Flux at the moment as it happens - it's due to launch in a few weeks and I think it heralds the future of energy tariffs for those with solar and battery, just like Octopus Go did with EVs... :-)
Some observations:-
1) I have Octopus GO and heat our tank off peak at 7.5p/kWh, which lasts the 2 of us almost all day.
2) Shelly wifi power monitors, switches, and scenes can easily be set up to use solar that might otherwise be exported. No code writing required and much cheaper than diverters, too!
I will have a Shelly 1PM monitoring my generation and a Shelly 1 switch to turn on my pool pump and heater when my generation goes above 1.5kW and off again when it goes below 0.5kW. The thresholds are easily changed and time delays can be added as desired. A similar system could be used with an immersion heater too.
3) Octopus only offer a 4p/kWh SEG if you have GO, but as far as I can see, I can sign up for Scottish Power's export tariff at 12p?
That's a brilliant setup, Mike - I need to take a look at these Shelly units. On 3) I wondered the same! That would be great if it were possible (maybe Octopus says you can have GO but you must take 4p SEG with it?)
I have GO with no SEG so far because I try hard not to export at all!
Correction: I don't think I can use a Shelly PM1 to measure solar generation. It will have to be a Shelly EM with a CT Clamp. That puts the cost up from £40 to £75....
Gary you need to change your channel after this video to “Gary does Global Solar” thank you for another informative and thought provoking vid.
Love it! Thanks Andy :-)
Thanks for the interesting video. However I purchased my Eddi last year so I think I'll stick with it. I knew at the time that the payback would be tricky but I like the idea of having some hot water without generating CO2 locally. I use Octopus Go in winter which means my export rate is only 4.5p - I will probably switch back to Agile Export (or whatever it is called at that point) in the summer. In the meantime I will have a word with my neighbour and ask her to stop using the vacuum cleaner so much.
Hi Graham, that made me laugh! :-)
Btw, I really like the concept of Agile, but is it actually viable at the moment? The rates always seem to hover at the ceiling these days?
Great video Gary and food for thought. I recently switched from Go to Flux which was a no-brainer. I'm also waiting on a Solaredge diverter from my installer but now I'm thinking I should cancel as it does not seem worth it. I have an EV but rarely charge at home (free at work for the moment!). You really need to keep on top of the changing market and tariffs to get the most of things, and videos like yours really help to navigate the system. Thanks.
This is great feedback - thanks for the taking the time to write it - very much appreciated! I canceled my Eddi just before my installation and I'm happy I did that. All the best with whatever you decide!
@@GaryDoesSolar FYI I cancelled the diverter so I’m £600 better off already!
@@tetrapanax1 I saved money too when I cancelled my Eddi, but then I immediately spent that money on an EPS! 🤣
Excellent presentation of a consideration that is up till now largely overlooked. Keep up the good work.
I predict that in the near future there will be a demand for home owners with excess capacity at mid day to export at a good feed out rate from say 4 to 7 pm which can be provided from your battery, and you will have enough left to get you through the evening for many of the sunny, longer daylight days. As batteries become less expensive, it will be cost effective to get a larger storage battery and everybody wins.
Then fossil fuel can be conserved to be used as a supplementary energy supply on cold, cloudy, windless days.
Thanks the great feedback, Cornelis. And I like your thinking 👍🏻😀
Thanks Gary. Interesting and thought provoking as ever. I have a 4kw solar array installed in 2011, so still get the highest feed in tariff, currently around 62p/kwh, but with an assumed export rate of 50% of generation at 4.5p/kwh. My understanding is that I cannot take advantage of the higher export rates available with Octopus without jeopardising my feed in tariff, and recent quotes for installation of a battery system have recommended a connection to batteries, but to do nothing that affects the supply to the solar generation meter. As all our heating comes from oil, and we only get 4.5p/kwh export tariff, I fitted an Immersun (an easy DIY job) about 8 years ago which enables us to turn off the oil boiler from April to October except for the dullest of days to provide 6 or 7 months of free HW which to me makes the diverter a no-brainer, particularly as it doesn't affect the 50% export assumption. In practice, we try to use the solar as we go by timing the use of dishwahers and washing machine use to the 3 hours either side of solar midday. At age 70, I'm looking for a payback time of no more than 10 years for obvious reasons. 🤣 However, we are in the fortunate position of having extra south and west facing roof space available for an additional 4kw array, so I'm always open to ideas. Presumably with ASHPs having an efficiency rating of up to 400% it would make sense for those who have them to divert power to that rather than to an immersion to provide HW?
Hi Roger, yeah, I wish it weren't so about my conclusions in that video - but over time, we are slowly but surely moving away from fossil fuels, and with talk of wholesale prices coming down again, maybe solar diverters still have life in them yet!
70 is still young in my book! :-)
Regarding heat pumps, the more I hear about them, the more they just make sense for home heating and now water heating. I plan to make a video on them soon - it's just hard finding the time at the moment - and that's with me only working 3 days a week in my day job - lol
I'm also like you 4kw PV and have a FIT (from 2015), this is still better than the current best SEG rates overall. I have an ASHP, it does our heating and water, during winter it is working away at night a lot. Surely if there is a diverter keeping the water warm during the day this means less work for the ASHP during the day and when the sun goes down. Issue is when the ASHP kicks in it needs to draw more kwh than your solar can produce so will take from the grid even when sunny, a solar diverter will just use surplus so the ASHP should kick in less to keep water warm meaning less grid use overall. Seems to me in my case a diverter would be very beneficial so am going to install one.
At first sight, I don't get much benefit from my Hot Water Controller. But it's a relatively cheap investment. While you are right that you make more money on current export rates, the money saving actually exists in the future:
- HW Cylinders don't last forever and they need to be replaced. But with a HW diverter, you can buy a cheaper HW cylinder that just has an immersion heated but no heating coil pipe. You can also delete all the associated plumbing pipework for the heating loop. In other words, you the opportunity to have a simpler, and therefore cheaper system at replacement time.
- I have one less reason to keep my gas boiler. Before solar, I had a gas hob, hw heating and space heating. Now I just use it for space heating, and that gives me a stronger foundation from which to make the leap to alternate methods of heating (including air to air heat pumps which are much cheaper to buy than air to water systems).
Hi Anthony, I think you did well, buying when you did. Since then, prices have rocketed :-(
You raise a great point about getting away from gas. We used to have a gas hob as well, but it's now electric. I'd love to get rid of the gas central heating, but without government help, the cost is too high for me. I've got quite a lot of rooms to heat so, although I love the idea of a2a heat pumps, I'd need quite a few, maybe?
Interesting point about the hot water cylinder - we recently replaced ours (£1,500) so wouldn't want to go through that again in a hurry!
Hope all is good with you. Looking forward to your next video :-)
Very useful and interesting - we are in the middle of having a heat pump installed - so it would be nice to have your calculator updated for this. (I tried increasing the gas boiler efficiency to 300% but no go). Also I am on the old tariff for solar as someone below mentioned - I think this means the payback period will be very quick but it would be nice to see it in black and white on your web-page.
Cheers Mark - and yeah, I am hoping to get round to the topic of heat pumps before long! So many topics to cover! And I'll sort a calculator for that when I do... :-)
Here in France, water heaters tend to be electric only, and the export rate is very low (and not possible if you install it yourself).
However, with my SMA setup the Home Manager can switch on up to four appliances using WiFi plugs (€60) allowing cheap use during the day.
And I'm not sure if overall fossil fuel conversion to electricity is anywhere near 50%. The EIA states that in the USA overall conversion efficiency is under 40%, with gas being the best at 45% (in 2019).
Hi David, sounds like you've got a pretty good setup there!
Regarding fossil fuel conversion efficiencies, this makes the case for solar diverters even worse than I thought then - crikey!
These solar diverters are not a well known entity, at least among the tradies I've spoken with. I've been looking for something like this for over a year now for my electric only hot water system. I can't talk in generalities but all the off-peak hot water systems I've had over the years are electric only so my installation of one of these will always put me in front irrespective of the feed out tariff.
Thank you. I now have a physical device type to talk to my electrician about getting installed.
Cheers 👍🏻
Just moved to Outgoing Octopus Fixed for my export, so I guess its time to move back to gas water heating - feels wrong, but the figures don't lie. Good video as always.
Thanks Jim! Yeah, I’ve just switched on the gas heating here. Hoping to get a heat pump before long…
Another great explanation that should get a few head scratching dilemmas sorted.
Thanks Mathew - I'm just wanting to give people information and tools so they can reasonably accurately assess the benefits of a particular approach, before spending lots of money, only to have regret later.
(Like me, I bought an Eddi and as I'm planning to make use of high export rates, it's no use to me any more - lol)
Thanks Gary. I have a solic 200, installed after two iboost failures. Worked very well. But since installing additional solar with batteries, and switching from FiT to SEG with Octopus, I've switched it off. Doesn't feel logical to export, but I think it's because we've been conditioned to use every bit of energy up ourselves.
You're most welcome. My videos are really just getting people to consider all the options open to them :-) Self-consumption is always best If you can, that's for sure!
Want to sell me your solic ?
Thank you for this. After using your utility I worked out I would never get payback on the Eddi due to be installed in 7 days time. Cancelled and £600 better off😊
You’re most welcome, Martin. And I did the same for my own installation week before last. It’s such a shame though as I really like the concept of the solar diverter 🤷♂️
Why does no one talk about solar thermal any longer? Isn't this an obvious starting point for hot water, before PV? Keen to hear your views!
Good question. The problem with thermal solar is that it’s expensive, less reliable, requires additional water pipe work and possibly a new tank. But more than any of that; it’s single use case. The only thing you can do with the sun’s energy is heat the water in your tank. And that doesn’t take too long to heat either.
Solar PV on the other hand, can do the same, but it can also power your house, charge a large to power your house when the sun goes down, charge your EV, or even allow to make money via export. It’s also much more reliable 👍🏻
Not sure if I can fully agree with your logic here. Firstly, the assumption of my neighbor (or anyone else on the same grid for that matter) needing my extra produced Kwh is not very likely, as mostly when there's overproduction on my solar, there's overproduction basically everywhere as consumption during those hours is generally lower. Add to that the fact that if I don't divert that Kwh into my water, I'll be needing to heat that water using other sources at some point anyway (which I'll then be taking from those environmentally worse options). So if you're thinking financially, you'd divert unless you get a really high export fee (as in higher than what you pay for import), and if you're thinking environmentally, you'd still divert to avoid having to heat using other sources.
Hi Peter, thanks for taking the time to comment. Now, even on days where there is a great deal of solar, it only represents a small percentage of total generation that day (
A good well articulated view on how to use any excess generation. You could also make a similar argument (environmental) for battery storage, depending on when you decide to store the energy. If I decided to export my excess during peak at 5pm (or even discharge too) then charge up later in the evening/off peak when the grid is cleaner, then it would work out more environmentally beneficial, but probably not financial. That is of course if you are on Flux and have a large amount of solar where you ALWAYS have excess and battery to export when prices are high.
A caveat though which I can now happily interject, If instead of the water being heated by Gas boiler it was heated by a heat pump, this would knock off the calculations, factor of 3 for hot water SCOP?
Thanks for the great feedback. My next video is about Octopus Flux - and I’ll be looking at the numbers around just what you describe.
The more I hear about heat pumps, the more I love them! They’re just so efficient that diverting excess solar into them can only be a good strategy, whatever your motivation (financial or environmental) 😀
The SunSynk inverters have a built in auxiliary to feed the hot water from excess solar so no extra cost. On the question of export, Octopus only pay 4.1p if you are on GO and as I have 4/14p until June I can’t consider other options until that date
@@mikejoseph425 That's pretty cool about the SunSynk inverter! And completely understandable that you'd stay on Go at that rate for as long as you can! 🙂
We've just had solar installed, and so until we get the DNO sign off back (ETA 2 months!) and MCS certificate (couple of weeks), we were exporting for free.
I purchased and installed a "solic 200" for £215. Not only is it about half the price of the iboost and Eddi devices, it also has a 10yr warranty compared with their 2yr warranties! It's not as "smart" as those devices, but I don't need it to be! With some clever wiring, you can ensure your inverter doesn't see the diverter usage and thus causes no battery drain issues.
Hi Ashleigh, how are you find your installation. After my nightmare of a journey (over a year!) my installation is going in as we speak :-) So far, everything is looking good. I bet you're happy to have yours up and running now, just in time for the longer sunnier days... I think you're right about the solar diverter units - they really don't need to be that complicated - the basic functions are sufficient. In the end, I asked my installer to take back the Eddi I ordered - I'm planning to export a lot (if I can) so no need for the Eddi. With the money, I've asked the installer to put in an EPS instead (just a little more than the cost of the Eddi). The battery drain issue was indeed one of the things worrying me about the Eddi as my batteries are DC-coupled - and that means the Eddi can't really see them...
Great vid, interesting points. I have a 4.5p off peak rate for 5 hours for another year so Octopus would be significantly more expensive and you have to move your supply to them to get those rates. But the 12p rate from Scottish Power looks like you don’t need to move to them. I’m on 5.6p SEG with EDF so 12p is over twice the rate. I export c. 50kWh on a sunny day at the moment and will likely get closer to 100 by the summer when GSHP heating for home gets turned off so this is quite a bonus. Thanks for bringing this rate to my attention!
Hi Craig, thanks for kind words, and also the detail on your situation. Even if just 50kWh export, that's amazing! Sounds like you likely can't go wrong with any of the Octopus tariffs, whatever you decided! :-)
@@GaryDoesSolar Some complex maths needs to be done when I come off the EDF off peak 5 hour 4.5p rate. I have 3 phase and 4 EVs as well as GSHP (I have no gas supply) at the house so I really use a lot of off peak (50kWh -150kWh most nights in autumn winter and spring) and Octopus have a lot higher off peak rate and a smaller window, 3 -4 hours I think. I'd have to see if the SEG rates were suffient to claw back the addittional off peak costs. Power abritrage I think they call it.
Came back to this so I could copy the link to forward to a Forum I'm a member of. Can't believe that I originally missed the Roman Emperor thumbnail - very good👍
Haha - you didn’t actually miss it first time round. I discovered faceswapper.ai the other week and thought I’d update the thumbnail for a laugh! 😆
Good work, very enjoyable.
Thanks Stephen - glad you enjoyed. It was fun to make as well :-)
Very good analysis. The public has very little understanding of marginal energy production. The problem is news reporters are not interested in doing the work to understand our energy supply system. They are part of the woke generation who never learned about critical reasoning from their education.
Thanks Phillip - and I'm hoping that my videos provide a good start for people trying to understand the world of solar, and that they don't just believe what I'm saying, but check things out for themselves :-)
Cannot believe the details keep moving so quickly (your report Gary is showing as a year old). Here Down Under we are now facing negative feed-in tarrifs. Currently my FIT is a meagre 5c so to me the solar diverter is a much cheaper and more attractive option than a battery with high upfront costs and doubtful savings before replacement become necessary ... not to mention fire risks. Your thoughts now please Gary. Is the situation changing likewise in UK as here in Oz?
Ah yes, Mark - you’re totally right - and this is the very topic of my next video which will be released tomorrow! Declining export rates and Solar diverters perhaps becoming back into fashion 😀👍🏻
Great video. Just a caveat. The high export tariffs from Octopus aren't available if you are on an ev tariff such as Go or Intelligent. You will be limited to the standard export tariff which is 4.5ppkWh I believe. I don't have a solar diverter and won't be getting one. I will simply switch my immersion on when there is excess solar. As I am on an ev tariff it pays to use as much as possible before exporting.
Hi Phil - thanks :-) And yeah, if you have an EV, you'd most likely prefer to put any excess solar into your car than exporting it...
Great video, as always. I realise it’s out of context but a storage battery means you can divert solar and heat at the immersion’s full 3kw. If you have home automation something like a Shelly plus 1pm costing circa £20 could be used. That doesn’t resolve the environmental aspect though
Thanks, and I like your thinking! :-)
Well here the "solar diverter" is a shelly + 3 phase relay with a home assistant automation (so like 50€) and I have no gas option to heat the water. So heating with the excess solar makes a lot of sense since otherwise I need to heat with electricity of the net.
Sounds good.
Hi, thank you very much for such a detailed video. However, as EV owners on a smart tariff Octopus only allows a SEG of 4 p per kWh. So I am going for an Eddi. Hope it makes sense.
Cheers for the kind words 😀 Yeah, it’s a shame the EV tariffs have a low export rate compared to others :-/
Makes perfect sense to go for the Eddi then 👍🏻
Thanks a tonne . I have learnt so much from you :-) I m having my setup next month :-)
Gary, thanks very much for a very timely release. Whilst mot touching on the subject of diverters, there is an extremely detailed comparison on the web looking at GO & FLUX.
Apropo nothing to do with this, the actual quality & integrity of some solar sales staff have a lot to be desired 🤭 .... the Enphase system works for an hour longer each day than any other system .... virtually all inverters are made in China, you'll need 24 panels & 2 inverters (2 of us in the house) etc. 🤣.
Thanks again for the fantastic output, enormously appreciated 🙏🏼
@@soumyanilsaha4704 I wish you all the best with your installation. And mine goes in week after next... :-)
@@nicflanagan6662 That's so very kind of you to say. I work very hard on all these videos and I would say that 99% of the responses I get are great. But you know, there are always one or two people who just want to complain (like, I'm forcing them to watch my videos or something 🤣) - I could imagine this would cause a lot of UA-camrs to say "why do I bother?" and give up. But comments like yours make my day - thank you! 🙂
Some solar sales people remind me of some double-glazing salesmen 20-30 years ago. Whenever there's a new market forming, there will always be cowboys jumping in to make a quick buck, and I hate that. It's one of the reasons I started this channel in fact...
Do you have a link to Go and Flux comparison please? I'm working on a Flux video just now...
Smart guy ! Should be minister of finance !
:-)
Gas is 0.12/kWh, I’m exporting at 0.04/kWh, it still makes sense for me.
If I have spare solar capacity then chances are the solar farms in the UK will have tonnes of it - so surely it’s more likely that shortfall is covered by renewable sources than coal?
Hi Will, great that a diverter still works for you 👍🏻 Are you on an EV tariff? I guess that’ll be the same for quite a few people.
Regarding UK solar generation, today it only makes a small percentage of total supply (
that's an interesting point - if you have excess above your battery and baseload it may likely coincide with a higher percentage of solar in the grid mix (Scenario B)
Excellent video with your usual concise clarity. Thank you.
I have an old FIT solar 2.5K installation with eddi and Zappi. I have an EV and am on the octopus intelligent tariff.
This excellent tariff has saved me a huge percentage, and the data from myenergi and octopus has enabled me to maximise savings to the extent that I am using no more electricity than I was before I got the EV, saving on the tariff and almost 4K in fuel.
On IO tariff, export rates are low. Do you have any thoughts on going bigger on solar plus battery, exporting on the flux tariff vs status quo, or just adding a battery.
I’m retired, so EV can charge on excess solar during the day.
Hi Steve - thanks for the kind words :-) That's an amazing result with Intelligent Octopus - I'm soon to make a video on that tariff as it happens. It looks to be the eventual replacement for Octopus Go.
Flux is a great tariff (I'm on that one) but if you have an EV, you're more likely to want to put any excess into that, rather than export. Many people with EVs see Go or IO as the best option...
In Australia you only get 6c-8c feed in tariff yet the cost of heating water at night when you shower is up to 30+ cents
Sorry to hear this. I hope more and more energy providers start to pay a better rate for export. If you think about it, your export goes straight to your neighbours - it highly unlikely to get past the sub-station. And that means the grid doesn't have to both supply (and more importantly, transmit) that same power to your neighbours. Everybody wins, in my view :-)
Gosh. More to think about. Ive had solar thermal for 15 years. Self installed and worked great until the controlled went pop. Now PV has come down I was considered switching and using a diverter. Heat pump install is beyond my means and insulation upgrades are a better use of finances. So heating water in winter is my biggest challenge if I ditch our trusty heat only boiler. Enjoy your £50 from Octopus. Thanks
Great video and diagrams as always Gary. Hope you don't get hate-mail from the power diverter manufacturers...!
Hi Chas, thanks - yeah - it's all PowerPoint animation! :-) Maybe one day I'll take the plunge and go for some proper animation software (another learning curve though). I moved from iMovie to Final Cut Pro last month and it's a great tool, but I'm on a trial and will have to pay for it soon!
Regarding hate mail, I'll let you know! :-) ... but it's hard to argue with the numbers... market dynamics change and companies in that space have to adapt or die, I guess...
Interesting analysis, the issue of marginal (gas) vs. average (variable wind etc.) power generation is a good point, and there are reasons to look at either one.
Two thoughts:
1. I think this just goes to show how the payback calculations are fraught with difficulty. I didn't order a diverter but did order a T-Smart immersion, which is cheaper and you can control it from your phone or put on a timer. After all, we've got a home battery so that can smooth out the difference between the solar generation and the immersion requirement (though that does mean extra cycling of the battery).
It was over 8 months from ordering our system to installation, during which time Octopus Flux was invented.
Who knows what the energy prices for gas and electricity will be in one year or five years' time? Having the control of the immersion heater is quite valuable for me, but I don't know if it will pay for itself.
2. What about heat pumps? If you've got a heat pump that heats hot water then I expect this changes the calculation again, since it will be so much more efficient than a gas boiler. If you've got a heat pump with a timer setting then you can run that off the solar and it is all the more efficient. Obviously then the case for a solar diverter drops off again.
Great points, Doug. I'm hoping to make a video on heat pumps before long. They just seem so in tune with solar and off-peak tariffs - like they were all made for each other :-)
@@GaryDoesSolar Look forward to it!
Heat pumps I understand are better when on constantly. Especially in winter with heating going you just want the heat pump to automatically come on when needed and top up the water temp. With timers you start getting drops in water temps depending on weather and when the pump comes on it has to work extra hard to warm things up again.
I installed an immersun ( the old co that went bust ) in 2009. It has produced nearly 9000kw so far. I am just applying to export having added more panels and your calculator shows a £28 pa saving. As the cost of the immersun is now effectively zero it is a simple trade off with my wife preferring constant hot water at all times to having to turn on the gas. When the Immersun dies I won't replace it but meanwhile comfort at a cost of £28pa is the winner
Sounds good 😀
Thanks to your tool I found that the converter would never pay it's self off for my use case
No worries - very happy to have been of help 😀
I have been using an Eddi for a year now and find i use it as a water heater in the summer and the second output goes to a heater in winter as i can heat my cylinder on Octopus Go. Having the relay board also means we can get an idea of our water temp. Its also useful for its energy monitoring function which combined with a Zappi means i consume 90% of my generation without a home battery.
That's a great setup, Wayne! Thanks for sharing :-)
Great video.
Cheers William :-)
Hi Gary, just for the record, I came from Jim's channel as I have started looking into EVs. I live on a small holding so have the possibility of installing more panels than I actually need. I know there is a break even wait but have you looked into whether going for overkill and installing more panels than you actually need purely to export? I'm wondering whether it would be a good investment?
Welcome! 😀
So, for anyone adding solar panels to their property for the first time, I’d always recommend maxing out the number of panels given the one-time installation costs (scaffolding etc.)
I’d suggest the same for anyone adding panels to an existing installation, but the cost of installation against the expected generation of the new panels might not justify the investment.
@@GaryDoesSolar Thanks Gary. I don't actually have to put them on the roof, I could potentially build a frame or something.
@@stonkerontheroad9609Oh, that’s brilliant. With the very low cost of panels these days, it’s definitely a route to consider 👍🏻
@@GaryDoesSolar I could look into having my own little solar farm 🙂
Hi Gary, excellent Chanel and great advice. Could I enquire about a 3 phase solar PV setup with the Eddi diverter and battery storage. Is that possible?
Hi Amjad, thanks for taking the time to comment and also the great feedback :-) Now, I don't know the answer wrt 3-phase but perhaps others can comment...
Thanks Gary, I have been told, Eddi will become redundant and not all battery storage work on 3 phase
I use a SOLAR iBOOST+ to divert any surpus and this is to my water cylinder but when heating it stops it goes to a second channel which is a 3kw storage heater in the lounge so is warmed up ready for the evening period, During the winter time the Storage heater is charged up on the GO tariff 00.30 to 04.30 am as I have a EV Car
Hi Janet, sounds like a great setup! Glad the diverter is working out for you :-)
For those of us on the old feed in tariff who are paid the same irrespective of how the electricity is used using a solar diverter (or indeed a battery system) to use the excess electricity makes sense. What was not fully analysed was the cost effectiveness of the other schemes. The diverter was targeted as the bad boy without full comparison with the other options.
Hi Ralph - thanks for taking the time to comment. The trouble with government incentives like FiT, is that it distorts the market (usually for all the right reasons, but a distortion none-the-less). As FiT is no longer available to anyone, and the solar market is really only just getting started in the UK, it should not be used as a metric to prove the diverter use case. And in my video, I could not prove the case myself, as much as I really wanted to do so :-/
The thing here is that the share of energy production varies during the day and the export price does too. So the hours when you have excess solar are the same when everyone else has. That means you get almost nothing for exporting moneywise and around those hours production is close to 100% renewable anyway (at least where I live). Even then, I agree that is not worth all the investment on the diverter just to heat water
For the tariffs in the UK, the export rates are fixed for certain times in the day - they don't vary depending on renewables production in the country. But it sounds like that where you live, they do? What is a typical percentage of solar production against overall demand? Here in the UK, it's less than 5% (although wind is sometimes >50%)
@@GaryDoesSolar Here we have a different rate each hour and is set the previous day according to expected demand and weather. Most days is 20% wind and 5% solar
Thanks Samu - it's good to hear about how tariffs work in different countries. This sounds very similar to the "Octopus Agile" tariff here in the UK - which is not for everyone, but could become more popular over time.
dont forget UK solar installs done up to April 2019 can be on the feed in tariff scheme and are paid a deemed export regardless of export .
Hi Wayne, true. I tend not to talk about FiT as this is a closed scheme now, as those on it are generally still onto a good thing. It was designed to kick-start the consumer market, and it seems to have worked well. I'm wondering though if rising export tariffs get to a point where even FiT is no longer the best way? What I mean is, for those on FiT say 5-10 years ago, they may be better off upgrading their panels (perhaps doubling array size)...?
@@GaryDoesSolar Another great video Gary
I understand your point, but it really depends on your set up beyond the pv system itself? For example, as well at an EDDI, I have a Zappi and 17.5 kwh battery and an EV. The FIT scheme assumes 50% of what I have generated goes back to the grid. In reality, I export now less than 5% back to the grid, plus you still get paid for each KWh you generate. Those are worth approximately £750 p.a. (3.9 kwh) in cash back. If you upgrade your array to anything above your original size then the FIT payments stop (you can replace like for like). Undoubtedly, there will be a point at which the size of the array would be beneficial but at what cost and what size? Given most are on either the 20 year payment or in my case the 25 year payment scheme , I imagine would have to at least double the size of their array which in itself is likely to require a further £10,000 investment. I would therefore suggest that you are correct on an solar diverter for those on SEG payments but possibly not for those on FIT payments.
@@SimonFranklin-wr9yu Thanks for the kind words. And you've just shown me just how good the FiT scheme is - wow! Very hard for a SEG scheme to compete! 😳😀
Really interesting angle, i hadn't considered exporting as a means of reducing somebody else's carbon footprint.
On the energy mix, i think you're more likely to be biased away from the fossil fuel generators as solar produces best in sunshine which is when fossil fuels are alost least likely required (i.e. during the day on bright conditions when least likely for high electricity use)
Hi Bob, yeah - I really struggled with trying to figure out what happened with that 1kWh of export! Take a look at my pinned comment - I'm convinced it replaces marginal generation, but I'm sure that's all up for debate still!
The other thing to consider in your example is that the water heater is a resistive element and therefore 'losses' are lower. The neighbours vacuum cleaner uses a motor which may have a power factor of '0.6' since you are powering a motor - this will vary with brand. On a 1kw vacuum cleaner the neighbour only pays for 1kw, but the power company is supplying approx. 1.6kw - thus 0.6kw 'wasted'.
This is a prominent issue with battery generators such as EcoFlow which seem to not last as long. It will provide power during a blackout - but inefficiently for many household products (Laptop - 0.41pf), freezer (0.5pf). Thus don't buy these products in the hope of charging at night at the cheap rate to power equipment during the peak rate day - you will be disappointed!, since like the power companies the EcoFlow is supplying the power factor losses.
Industrial companies running motors pay for the pf losses, but residents don't.
Good points - I guess was just considering the actual power (1kWh) that the neighbour would be billed for, regardless of how they used that. After all, they may choose to use a resistive heater instead of a vacuum cleaner?
@@GaryDoesSolar Firms like EcoFlow advertise their equipment for powering electronic equipment within the home during a power-cut. Yes it will do that but what's missing in the fine print is the effect of power factor. A tradesman working on site will add up the power of his power tools, and the time spent using them during the day, and choose what they think is a suitable generator only to find they run out of power by lunchtime. No fine-print to try and educate them - so the tradesman ends up have to buy a plug-in battery pack. So my comment is trying to educate people since EcoFlow don't.
However being on FITs we don't get any more money if our electricity is exported. For us it makes much more sense financially to divert the excess into our thermal store tank. Another 13 years till our fits end.
Hi Dave, yeah, if you're part of the FiT scheme, you're onto a real winner - Deemed export AND hot water! :-)
For me the calculations & logic of this presentation are most interesting; however I beg to differ. Why?
I've had solar PV since October 2011 & two of the old style Immersun power diverters that I self-installed purchased in 2012 (new - master) & 2013 (used/much cheaper £50 - slave). The extra solar panels are rated at well above 4.0kwp but are limited down by a 4kwp Sunny Boy inverter. Payback was exactly 5-years for the basic system.
The house has no gas supply or open fire or wood-burner; it's all electric. The two Immersuns are part hard-wired & part wired via switches & normal 3-pin sockets, but always on a separate circuit away from the mains supply. The Immersuns heat my immersion tank, 7-litre shower reservoir tank, 2x very old storage radiators, kettles for hot drinks, oven for baking & occasionally a 2-ring thermostatically limited mini-cooker. I manage the power-switching via rotation, as & when needed. NB. You can't use Immersun pulse power to power anything that has transformers, electronics, motors, inside; they'll be damaged.
Output is currently in excess of 5,000 kwh pa & receiving around £3,000 pa in total FIT receipts, (not from Octopus, but I'll consider the merits of Octopus later, although I didn't like their T&Cs small-print last time). My electricity import bills from Utilita are less than £100 pa (zero standing charge), & they even gave me £400 over the last 6-months as a general grant (6x+ years of supply free). Original budget was 20.4% IRR, but even with the costs of the extra below, I'm running at 15.4% better than budget.
Currently self-installing an upgrade with a Sunny Island hybrid inverter & 4x massive AGM batteries, with a MyEnergi Eddie (only £390, as the new hybrid inverter won't talk nicely with the old Immersun units - shame). Add a further year to payback for these extras.
I think that IF anyone has gas-supply, a BIG lithium battery (maybe Tesla powerwall?) & Octopus export tariff receipts, then your reasoning stacks-up well. If anyone's interested, my data is on the website of PVoutput.org & search for JohnnyK's-PV; I'm in the UK. I'd recommend solar PV in almost any guise; it makes so much sense. Keep-up your videos Gary; they are interesting.
Thanks for taking the time to comment, John. I'm not sure I understand where/why you disagree with my reasoning in the video though. Can you explain, because if I want my videos to be accurate. Many thanks!
@@GaryDoesSolar Hi, I'm guessing that your reasoning is correct for the vast majority of normal people. However I am not an average person in an average household & choose to live the life of a 'green-nutter' - lol.
Just taken a look at the two links that you have of Octopus Flux tariff & your calculator.
First I don't have a smart meter & even if I wanted one, my electricity company will not fit one, as I have a 3-phase supply & use economy 7 tariff. Tried 3x times in past years, they won't fit one, but now I would choose not to have one anyway. The export rate offered of 25.26p/kwh sounds great though, as I currently only get 4.25p/kwh, but that is mitigated enormously by my FIT generation rate received of 60.23p/kwh. Also I currently have a Utilita smart tariff (even though I don't have a smart meter). There is zero standing charge; that is recouped via a mega expensive 90.32p/kwh + 5% vat of a day rate. The big but, is that I use so very little on day rate import that my annual bill is currently estimated at £25.93 pa (yes.... I didn't look-up the exact figures in my original comment when I stated that my house used
Hi John, this is great input, and I don't see you as a "green-nutter" at all. I think others will be interested in your experiences with all of this 🙂
@@GaryDoesSolar Although I've limited my comments to the subject material of your video & therefore of the economics of solar, diverters, battery, etc. my main interest is in trying very hard to live a more sustainable lifestyle. I actually put more time & effort into using as little as is reasonably possible of energy, food, water, fuel for my car, & growing/foraging food for personal consumption. Most people might describe it as an alternative/frugal lifestyle (if they're being nice to me), however the economics really do add-up & I can save significant sums of dosh even on a very low p/t income. I'm also living the F.I.R.E. lifestyle for real.
This is interesting and is worth the watch if only to make you think. BUT isn’t the point of the diverter that you can tell it what to do and when? So a mixergy tank could be controlled by it’s own controller to warm only what is needed, learn the families patterns, save water AND you can set tariff thresholds decide IF you want solar involved or not, use a boiler and/or mains, plug in a heat pump and this all makes your calculations different again.
BUT I thought you got the EDDI for example so you could do this and change your mind for when export tariffs like this are high, but change it back if they drop again.
Hi Jeremy, I love it that data is becoming more and more the foundation of how our systems will work in the future, rather than just basic logic. Your comment is a great example of how we can use data in this way :-)
Really interesting video. As I have an EV and a PHEV to charge, Octopus Go works better for me than either of the export tariffs. That means I’ll get just 4.1p for any exported electricity. The environmental point is a fair one, but I’m not sure. How far do we go with this, in summer do I get my neighbour to plug in his mower to my house to use my solar so that he isn’t using grid electricity? And do we have to check how much wind and solar the grid is receiving at the point of deciding? If it’s particularly sunny and windy, then the grid will be very green
Hi Billy - yeah, hopefully we don't have to go too far with such management :-) I think we just need to continually move toward lowering the percentage of fossil fuels in the mix...
Hi Mate
Thanks for the video.
I’m from Australia and here for example I pay 45 cents per kilowatt and if I don’t use all the power it gets sold back to the company for 5 cents per kilowatt …
So unfortunately here in Australia the only people making money are the power companies.
So it costs me 45 cents to buy and then they get it back for 5 cents !!!.
So in your Opinion and experience is this worth me getting the Solar diverter ??, I gathered it was due to how much the electric company gets back compared to the customer!!..
Cheers Mate look forward to your reply …
im in northern ireland and since the start (1st nov 22) of the EPG government help kicked in i have been exporting everything i can and plus a bit extra from my batteries.
before oct 22 the export rate was £0.0785 then and then after that it has jumped up to £0.1766. then plus with the EPG help the night rate went to £0.0158 import for a month (all november) then it went to £0.047 and it still there until the end of march 22. so i heat water at night, charge the car at night on eco7 (winter 1am-8am / summer 2am-9am) and export all the solar i can and i have also exported a bit from my battery every night too just to help
Hi Stephen, sounds like you've got a great strategy there. I love it that higher export rates are causing us all to re-plan what we do with out energy generation.
@@GaryDoesSolar the higher export = higher imports too sadly. for us with solar its fine until winter
I have a fit tariff {another 10 years left) and I'm credited with export calculated on my generation so If I export everything I make i'm only credited with half the generation. Subsequently if I use everything I make I'm still credited with a 50% export of my total generation even though I dont export a thing. So a diverter turns my water tank into a solar battery and I get to keep as much as I can of what I make. A battery would be great but without the initial high cost this is the best I can make of my 4kw system, which after 10 years has now paid for itself. When there's a decent amount of good sunshine I turn my hot water boiler off. I purchased my iboost for less than £300 and fitted it myself and its paid for itself over the 4 years I've had it.
Hi Chris - that’s brilliant. Yeah, you’re very fortunate being on the FiT tariff. For the rest of us, a Solar diverter might not make as much sense unfortunately.
You need 1.25kWh gas from your boiler in your example with an 80% efficient boiler, not 1.2kWh. The argument is still well presented, and now imagine you have a heat pump with a COP of 3, 4 or even better. Someone needs to come up with heatpump controls that recognise excess solar production
Good spot, Hans - thanks! And yes, heat pumps are so revolutionary - I can't wait until they become mainstream :-)
I am interested if you using a Air source heat pump running at SCOP of say 4. Surely it makes more sense to use that to heat your hot water. Rather than using solar diverter to heat the hot water tank at a much lower efficiency?
I don't know too much about ASHP for water heating yet, but I agree - they should be much more efficient than diverters. I'll be researching into this before long...
Hi Gary, great video and has made me consider the use of our Eddie which we had installed last year.
I have always felt heating the water with our solar instead of the boiler is a huge plus, but now I’m reconsidering. I will say it was a huge benefit having the programmable timer on the Eddie when our boiler failed last winter! Would the diverter make more sense in a house without a gas boiler? We intended to have our boiler swapped out for a Tepeo ZEB and with our induction hob won’t need gas any more.
Once capped off we will save on the standing charge each month so would that not offset the cost of the diverter? When the day comes we’re all banned from buying gas boilers in the future, diverters a have a place again don’t they?
Yeah, if you take gas out of the equation, things are looking better for diverters - which is good because I do love the concept of them 👍🏻
@@GaryDoesSolar That may be an interesting cost/benefit comparison to do as more people are having heat pumps installed. A friend of mine is building a new house and with new regulations is basically being forced down the heat pump route. I guess if you have a heat pump running from your solar is it any different to having the diverter?
I guess that’s the same for a Zero Emission Boiler. If I charge the boiler from the solar, then it’s the same job the diverter is doing. Adding another step to the process but essentially the same.
@@amcarvids5094 What make the heat pump more effective than a diverter is the fact that you put in 1kW of (electricity) energy in and you get 3-4x (heat) energy out. A solar diverter is just 1:1
Setting up your solar based on exporting to the grid is an inherently fouled design approach. First, it totally exposes you to the fluctuations of pricing, government policy or energy market. Second, you cannot make anything more energy efficient than using energy at the point of generation at the time of generation, directly. Just because at this moment you temporarily can make more money out of it does not mean you make a wise decision. In my country (and in a lot of others) it's not just that they dropped the export price but explicitly prohibited exporting because the large renewable ratio starts causing issue in some subnets and it would take several years of GDP to completely rebuild the eletrical distribution system.
Renewable energy: use it when you have it and where you have it for something you actually need. Whatever formulas or arguments you bring up it can be measured against this as a golden standard. If the result is that you should export energy and then buy it back because it makes more sense you know your argument is flawed.
Surely we have all had enough of Grid Tie systems, we have seen the greedy energy giants for the crooks they are, making excess profits and using the blood shed in Ukraine as an excuse to ramp up prices.
OFF GRID is the way forward.
@@richardsandwell2285 from where I see it power grid is a valuable service and irreplaceable in a lot of places. Residental homes are not those places. Single family homes today are in a great position to generate a good chunk of their power need and still use grids for backup so you don't need to mine entire South America for lithium. Grid companies should participate in this but probably not as the Great Sources of Energy, instead as real distributors and organizers. Our homes should use grid but not exclusively and not to a very high extent. This would also handle the issue you mentioned that they are not too much in a power position - both figurative and literal.
Hi Kobor, each country is different. In general, I believe exporting energy is a good thing, because it means less marginal fossil fuels being burned. And if you can get paid for that, even better. My own installation is designed to be as flexible as possible, in order to benefit from fluctuations in pricing and also higher export rates. I don’t view this as a ‘fouled’ approach at all.
Not sure I fully agree with the thinking process. The scenarios assumes that excess solar exported to the grid will be used at the time exported. If it is a sunny day as described, then there must also be other solar households as well as solar farms generating excess energy and no guarantee all surplus will be consumed by other users on the grid.
If there is a surplus on the grid then what happens (stored as hydro, curtailment etc)?
I would say it’s extremely unlikely your exported energy would make it past the substation. They are far more people without solar and home battery than with…
@@GaryDoesSolar I haven’t read the studies and so am shaky in the matter. If we use export payment as an example and indicator of demand, and today’s Octopus Agile export price (09/06/24), it ranges from 0.59 pence to 2.45 pence between 11:00 and 15:00. Does a low actively tracked export price not indicate a lack of/reduced grid demand?
@@georgechirayus4865 I would say that any time the price goes low, it's not an indicator of reduced demand, but instead an indicator of over-supply (typically wind and solar). But remember, in the UK, solar at most is only 10% of the supply mix (it is growing though year on year) and I'll be talking about the macro effects in a video I'm working on... In relation to your original question, take a look at my pinned comment to the video, which is my view. It's great to debate that though - always happy to be proved wrong! 🙂
@@GaryDoesSolar That’s a fair point. My assumption (of demand) was wrong on that. Would be great to see your macro video. 👍
It's a good job I didn't do it based on a payback calculation rather than just wanting to worry less about running out of hot water - our tank is slightly undersized for our needs due to size of the property (i.e. the physical space available for the tank).
I agree that it does lower my contribution to a greener grid, but the trouble is when I've got lots of export available there's a good chance the grid doesn't need it anyway.
...but to make sure my battery has priority my diverter ignores 250w export. So when I'm charging water I *am* still contributing slightly. If the whole street was doing that, that's still several kw leaving or being used locally on the estate.
If folk were all generating and using locally, the grid would be greener and less spike dependent in general.
I'm going to worry about my grid contribution once I see signs that grid scale storage is properly happening. Then there'll be an unarguable serious communal good argument.
Till then I'm in your top row: 4p export, import 12/40 on octopus go, and we have high water usage compared to our tank size.
In the UK were at between 40-70% gas for electricity, depending on the weather, time of day, and season. Generally this averages out at just less that 50%, and falling. Of that, 50% is imported (therefore about 20% of the total) and therefore higher carbon footprint than the other 50%. Coal is now a tiny fraction. Biomass is I think 10%, argue over it's footprint if you want. The point is, between about 50-70% of our grid in the uk is already renewable, depending on season, time of day etc., And of the rest the bulk is gas which is at least cleaner than any other fossil fuel, or nuclear and biomass. Some peaker usage is hydro the rest is gas or coal in mid winter. If we had proper grid storage, we could kill off those coal and gas peakers at the very least, and reduce the dependency on the base load generators.
So in the UK it really is purely a monetary thing - how good is your export. The environmental argument of making your own hot water does make sense. Arguably in winter it is more socially responsible to export.
Regards grid storage don't get me wrong for all this to work we need at least 12 hours of high response and several days if not a week's worth of slow response.
Expensive: but with the right mix of even current storage tech at varying scales, entirely doable.
Great points, Jez - thanks for sharing :-)
Its good news that SEG rates are increasing, but trying to get registered with Scottish Power is a nightmare. I’m an Economy 7 import customer with Scottish Power, which you would think would make life easier (as they have all my details). 5 months after submitting the SEG paperwork and many, many emails chasing up, I’m still waiting!
Sorry to hear this, Dave - and I hope they get it sorted soon. If you have a Twitter account, express your frustration on that and I'm pretty sure your SEG will be addressed soon after...
Your financial argument is fine at the moment because the better export rates are available because of the high cost of energy from providers. Those rates will drop off a fair amount when normal regular electricity is back in the 20-25p margin.
Agreed. And I’m all for rates coming down again 👍🏻
@Gary Does Solar so say we all! Our business rate is 72p come the start of April, just glad most of our usage is in the winter to drive the heat pumps with the business support and then solar picks up the the strain around April anyway.
We're having 6kw pv and a 9.5 battery installed on our house in a month so I'm looking forward to getting a tariff sorted. While the export rates are high I'd be tempted to set an Eddi to do nothing unless ones export was up near the export limit of 3.68kw (say 3kw) and then turn on. That would earn the better export rate and prevent the inverter having to limit its export to stay under the cap. As rates fall again, it's easy to change the setting.
@@MrDBT85 Wow, business rates are just crazy, eh?! But it sounds like you're doing all the right things to compensate. I like your thinking about usage management, and I wish you the very best this year! 🙂
The rising price of selling solar to the grid is totally or at least partially offset by the higher prices of gas and oil used to heat the water instead - or did I miss that this was taken into account?
Yeah, this should all be in balance with each other - everything should be based on wholesale prices. What we've seen (at least in the UK) though is that rising export rates have lagged rising wholesale prices.
The recently introduced octopus flux tariff is a game changer.
For the months one is net exporter of electricity it is easy to set and pays good export rates. Probably the Agile export will pay a bit more, but takes time to check daily the rates
Yeah, I agree - Flux and Agile are the way forward. I'm making a video about Flux just now, as it happens... :-)
Hi Gary, interesting stuff, thanks! I'm just about to make my decision whether to buy and install a diverter for my newly installed plant here in Switzerland. How comes you assume that every exported kWh is available for consumption by others? Isn't there way too much energy around in the grid anyway during a very sunny day which cannot be stored by the provider?
You're most welcome, Martin :-)
Your question is a good one. I'd answer by saying that your exported energy will likely never make it past the substation back onto the grid. That means it will be consumed by a neighbouring house, because there will always be a draw from the grid at any substation - even on a sunny day.
@@GaryDoesSolar to follow that up, yea, when you export from one house, it simply reduces the import rate at the substation for the neighbourhood, so the grid operator has to turn down generation going there (a tiny tiny bit) usually by turning down the gas or offering it to balancing services.
Thanks, very interesting discussion. Not applicable for me as I have a Combi and the cylinder was removed a few years ago.
I can just about manage to use all my solar with my EV , battery and other heavy usage devices. Never export anything from October through to April, over Summer only about 300 Kwh exported equivalent to £12 on SEG.
Thanks John for the kind words, and also for taking the time to say a little about your own situation. They certainly say that the best way is to consume as much self-generation as you can and by the sounds of it, you're achieving that :-)
I have a combi and a tank. I can pre heat the water so that the combi doesn't fire up. That said, I don't do it at the moment as the payments from the export are more than it would cost to heat the water using the combi. Where the tank does come into its own is in the winter on Agile. Price drops can then pay me to heat the water.
What about for those people who use Oil or LPG to heat water Gary, do you think it's still worthwhile for them either environmentally or financially?
Hi Kier, so the utility I developed is designed for gas, but I believe you could enter appropriate figures for oil/LPG. I’d be interested to hear from those who might have done this 👍🏻
Unless you build in a limited life-span for the inverter, it is counter to logic that you cannot get your money back eventually, if the cost of importing remains greater than the price received for feeding into the grid. Your assertion does work IF you assume an alternative source of heat (gas) at a price of 13p per kW.
Your theory re environmental impact becomes less cut and dry if you take into account the likely-hood that on those days when we have excess solar power to export, the grid will tend to be awash with green solar generated power. Especially on days which are both windy and sunny. As solar and wind farms increase, the more this will be the case. But excellent food for thought.
Yes, but how long is eventually? I show in my video that eventually might be decades...
On the environmental impact, solar today is < 5% of the national UK energy mix, therefore minimal impact on the numbers. You're right about wind - there are certainly days when it is above 50% of the mix, but my utility looks at a whole year, which is a more accurate basis for the numbers.
I agree, as wind and solar production increases nationally, the requirement for gas reduces and so the impact is ever smaller - I can live with that, given how much better things will be for everyone.
Could you not just use a timer switch on your immersion heater to heat the water at the time of the most solar power generation, at a fraction of the cost of one of these diverters?
The aim is to only use excess solar for your hot water. With a timer, if it’s not been a great day for generating, your immersion may well take all the electricity you need to charge up your batteries, leaving you on grid electricity that evening. The advantage of the diverter is that you get to use your solar, or store it in a battery or EV before it heats your hot water
Yes, you could. Just watch out for clouds coming over when the timer is on - you'll be drawing from the grid to heat your water during those times...
Thanks for the answers guys, useful information for a novice like myself planning to install solar panels plus batteries.
You can, but the eddi will divert whatever the excess is. So if you have a 500w excess it will only send 500w to the tank. Other methods that simply turn on your 3kw immersion when there is say 2 or 3kw excess still allow a lot of energy to be pissed away. For us on FIT it makes sense to use the eddi as we're getting paid for it whether we use it or not.
I am thinking I wasted some money on my iBoost. I am very happy with the rest of my installation. It was installed in December and I already surprised how much I generate on a good sunny day. I have also noticed the sun is getting stronger. The issue I have seen with my iBoost, twice, it has flattened my battery. For some reason it kicked in and then the battery kept it kicked in. I have upped the watt limit to try and stop it.
That does sound like a problem, Michael. Get onto one of the many solar forums and ask for advise. I’d imagine you’re not the only one with those issues…
@@GaryDoesSolar You will find this very interesting. I could see you making this ua-cam.com/video/yEihC5k1O00/v-deo.html
@@bazcurtis178 Thanks - I'll take a look 🙂
I actually came to the same conclusion about solar diverters when considering Octopus Flux.
It's actually worse when you consider a heat pump which normally heats DHW at night at the cheap rate.
If you divert and heat the water over the normal temperature your heat pump won't bother heating at the allotted time because the water is already hot.
But consider the efficiencies - the ASHP might heat DHW with a COP of three so only uses 1/3 of the electrical energy of your divert for the same temperature rise. So using divert only saves you 1/3 the kWh of what you might think and you are only saving against the cheap rate of electricity - not peak rate when the divert happens during the day.
And of course as you say, a decent export tariff blows the point of diverting anyway.
The Eddie needs a new purpose!
Agreed, John. And actually, I think more and more people are seeing heat pumps coming into their own now... the world is slowly changing in that respect :-)
I imagine that in the next few years we will see ecosystems that will do essentially all of this work for you (not to belittle your fantastic work).
Your standard punter wants one thing - lower bills. They don't really care how that is done
Thanks Nick - and I think you're right. These systems must eventually be automatic (reporting only issues), and perhaps even integrated directly into your energy bills...
Hi Gary, I’m about to have the Eddi installed and it’s a bit too late now but this video has brought up a point. I’m getting installed a 6.72kw system/16 panels with a 5.5kw inverter.
I’ve only just been told I’ve actually got space for 4 more panels which would take the system size to 8.4kw, should I still take another 4 panels despite the inverter size since the current pay back from exporting is good? Ideally I’d need an 8kw inverter to use all that energy myself and there’s no guarantee my DNO will approve a 8kw inverter. (5.5kw inverter has already been approved)
Hi Brian, thanks for taking the time to comment. I've never heard anyone say they wish they had less panels, but I hear people all the time saying they wished they had put more panels up there...
In terms of the financial benefit to you of putting extra panels up there, feel free try different scenarios in the utility provided with my video here: ua-cam.com/video/FvjuJQZRrvA/v-deo.html - this should help in your decision-making. I'd love to know what you decide to do in the end... :-)
Get the extra panels for sure, it makes sense to oversize the array anyway. I’m probably going to get a solar hot water diverter too but am aware it doesn’t currently make financial sense currently. Probably going to because you cannot predict what the tariffs will be in 5-10 years, and getting it now is vat free and inflation is rampant.
Thanks Gary & Richard, yes I’m still getting the Eddi as they gave it to me as a price match. I’ve spoken to my solar provider and they said I would have to change my 5.5kw inverter to a 8kw inverter to manage the load and I’d have to get the DNO approval again and there’s no guarantee it’d be approved and they’re ready to fit it now even though the weather have delayed them fitting the panels and the other kit I’m getting. I don’t know whether to say I’ll wait for the approval but now they’re inflating the price on the extra panels and inverter.
@@arnielegend Now, is your inverter a hybrid one? If it was, then even though it could only output 5.5kW, it can still charge a DC-coupled battery with any solar generation in excess of that (a great benefit of a hybrid inverter).
Irrespective, even if your current inverter cannot be changed (due to G99) it is still worth considering the extra panels because in the winter months, those extra panels will help increase your generation (remembering that you won't be getting anywhere near the 5.5kW limit in those months). The only question then is can your inverter support the extra array size? Questions to ask your installer, I guess...
@@GaryDoesSolar thanks again. The inverter & 2x batteries are Sunsynk. The inverter is an Hybrid one. The company that’s supplying me said with the 4 extra panels it’d make the an 8.4kw system and said the 5.5kw inverter wouldn’t be able to manage the load and would need an 8kw inverter which they don’t seem keen on supplying for me unless I was to push for it.
how does one use your calculator for an electric (no gas) water heater (flat import rates)?
Select “Electricity” instead of “Gas” in the drop down menu near the end of the utility for the days where there is insufficient Solar.
@@GaryDoesSolar Thanks! For a family of 3, $1700 total investment cost, $0.26 kWh imports and $0.04kWh exports (I don’t have gas), you tool estimates that it takes 24 years to recover my initial investment!!! This is crazy long. What assumptions go into your model? Thanks again for making this available.
@@DanielG0m3z The calculations should hopefully be self-explanatory but if I get time, I'll add further detail on those. Great that it's save you making a bad investment.
@@GaryDoesSolar Indeed! Thanks heaps
I guess most power plants - at least in Denmark - would also utilize the heat that is generated when generating the electricity, so burning gas just to get heat is probably not the best way to utilize gas.
Yeah, the only problem is, here in the UK, most homes are heated by gas - a hard habit to break... but the heat pumps are coming... :-)
We get 6 cents feed in tariff so definitely worth getting a diverter in Australia
Yeah, can't argue with that - hopefully, things will improve on the feed-in-tariff front, just like they did in the UK last year... :-)
I'm on FIT from 2015 , i saw the other day they are going to change it so you get more for export than generation, Is that right ?
I'm not up to speed on any changes with UK feed in tariffs - perhaps others could comment?
We're on a deemed export so all power we generate Is 'paid for'. On an annual average we divert 2.5kwh per day into the tank so in summer virtually zero gas and zero grid for hot water..
Hi Ken, you are one of the lucky ones, to be on a feed-in-tariff :-) Great stats - long may that continue!
@Gary Does Solar yep the system went in Jul '15 14×250W on two roof pitches 6SW and 8SE all on Enphase micros. . with an i-Boost diverter unit . Then panels peak at about 2kW-2.5kW and average 10kWh/day over the year, but because the panels are on the two pitches the bell curve for generation covers a wide spread of the day. The house only needs about 400w base for fridges internet stuff Alexa chargers etc.. our current net feed in from Ovo is about 19p/kW generated.. in hindsight an absolute no brainer
I'm using Oil to heat my Water has there's no Gas in my Village, since getting a myenergi Eddi fitted 3 months ago I've only used my boiler twice on Dull day's the other day's my Solar Array has given me Hot Water, I'm very pleased I had my Solar Diverter fitted 😍even though I'm on Agile Outgoing Octopus. 🤦♂
Thanks for taking the time to comment, Ian. Yes, it sounds like in your situation, a Solar diverter is perfect 👍🏻
This assumes you have access to and are using gas, in an all electric house the sum will change. I have an Eddi > Sunamp + Storage heater. I have no access to gas. Eddi pays back in a year.
Not at all, the utility has an option to select either gas or electricity for water heating in the times when there is no sun.
I am interested in Octopus' Agile account but I am still waiting to install my PV / Battery system. Should I wait until that is installed before switching as the online quote I got is not for Agile?
I think Octopus require all sorts of details about your installation (include an MCS certificate?) before they'll switch you to that. Best to wait until everything is in place, I reckon. Hope it all goes well for you though :-)
I am on Agile and you won’t regret it. I would recommend the Octopus Watch app to help track prices
Have you checked the Octopus Flux tariff?
I quite like the Octopus Flux tariff. Definitely one to consider. I am currently working on a video on that tariff, as it happens 😀
@@GaryDoesSolar I did look at it. I still believe Agile is cheaper. Flux obviously removes the risk. It February I saved £26 by being on Agile over the standard 35p rate. I charged the batteries overnight with 4 slots. February was a good solar month.
So far March has been a shocker 😀
Surprised you didn't mention just heating the immersion in the middle of the night when electricity demands are low and rates are cheap. If you are on a tariff with octopus anyway I would assume they have cheap rates in the middle of the night, so you could export 1kWh of solar at say 14p and then import it back at 7p at 2am (I don't know their exact rates). That way your solar export is used during the day when demand is high and the import is done during the night when demand is low so is likely from nuclear or wind generation.
Good point - would have been a nice segment in the video too. One issue I see though is that off-peak tariffs are not as attractive as they were a year ago either. And generally, heating by electricity is more expensive kWh per kWh than gas. Let me run some numbers to see if there is still a case to be made - thanks! :-)
@@GaryDoesSolar Yeah I just had a quick look at rates and not sure it would work.
I'm in Ireland where gas is current 13c ish per kWh, kerosene which I'm on is about 10.5c, and my electricity is 9c for 3 hours overnight. So with the efficiency loss on boiler it is cheaper (by a small bit) to heat with electric overnight. And it should be more environmentally friendly as overnight should be using wind generation a lot of time. But it still is marginal enough difference that its not fully clear cut.
I had thought you would have better night rates on offer as I know economy 7/10 used to be quite popular but from quick look not sure be worth it.
The other thing I was thinking was the eddi is quite expensive and I think a smart switch connected to home assistant could do the same job for a lot less. You would have to be careful about which switch due to high power. But something like a sonoff powr3 has 25A limit, or could use a smaller switch a contactor to be extra sure.
@@gillo100 Another factor to consider is solar adoption rates. As more people go solar, the peak demand will shift steadily to the nighttime and make that power more expensive.
@@notbatman1001 Yeah, will be interesting to see how things develop. The 'nighttime bathtub' is pretty deep though and will take a lot to fill it... so I'm hoping that there will always be a differential in pricing between day and night.
@@gillo100 If I get time, I'll crunch some numbers myself and see what comes out...
I'm still on a feed in tarrif at 5p per kwh so I guess it depends on how long these decent export rates would continue for. Presumably I'd have to give up fit to get new export rates?
Hi Richard, yeah, you most likely would. You may be best to hang onto your FiT for as long as you can! :-)
@@GaryDoesSolar you can continue on your FIT generation rate. You get paid for your generation by your FIT supplier still. It’s the 50% deemed export under the FIT scheme that you lose. Quite what happens if you swap your deemed export to one of the current export schemes instead and then want to go back later I don’t know. There has been nothing about that so I can only guess and say you cannot. So be certain when or if you decide to trade your FIT deemed export for a new export tariff that you are doing the right thing.
@@lynnfisher4396 Thanks Lynn - very useful info 👍much appreciated
@@GaryDoesSolar my pleasure
Some further information about the FIT scheme. The payments were guaranteed for 25 years, they are updated every year and increase in line with inflation. Last year our own generation rate was 60.23p per kWh generated and the deemed export 4.25p per KWH. We expect a letter in the next few days letting us know the new rates but as it’s the same figure as the pension increase it will be 10%. As you say elsewhere the FIT scheme was designed to prompt domestic solar installs and we feel very fortunate to have got one of the last full fat rates in 2012. After April 2012 the FIT rates were gradually decreased until the SEG scheme superseded it.
@@GaryDoesSolar thanks Gary. Great channel by the way and the only source of concise accurate advice I have found all in one place. Having spent many years learning about it myself. Cheers 👍
battery storage is not cost affective. unless have insainly hi eletricity rates.
Electricity prices a factor, certainly...
Solar diverters work when the sun is shining (obviously) and that is mostly during off peak times. This is also the time that the country's energy mix is extremely green so I am very skeptical regarding your argument that not exporting your solar will lead to higher emissions. In fact the opposite is far more likely, if you export during off peak times and then use gas to heat your boiler during peak times just before using the hot water then this gas is likely to be the dirtiest.
The thing is, solar, on a good day, is less than 5% of the national energy mix... There could still be >50% gas in that mix...
The logic makes sense but something bugs me about the argument. I realised it's the same argument put forward at the start of the electrification revolution and adoption of EV's. People did (and do) argue that powering high powered electrical items like EV's are worse for the environment as the electricity comes mainly from dirty coal or gas which is then inefficiently transported over wires to your home or to power a train for example. They claimed it was much better to burn petrol at the point of use. This argument is somewhat valid if the electricity mix is very dirty but of course it neglects to take into account that the electricity mix is ever changing and becoming cleaner. The best way to incentivize government's and be zero carbon ready is to electrify everything first, the energy mix will be cleaned up after. If we wait for the mix to become 100% renewable first before removing gas boilers then we'll never kick the burning habit.
Those are annual averages. On those days a house has excess energy, the national energy mix is likely to contain more green energy.
True, but you would have to look at the potential benefits on a multi-year basis anyway, no?
@@GaryDoesSolar No, if you're evaluating the impact of the installation choosing to heat water instead of exporting, you need to look at the mix at the time the decision is made.
Personally, I'm not convinced a diverter is much use without seasonal thermal storage.
@@jocramkrispy305 That's a good point. The problem though, is that solar diverters have the capability to monitor instantaneous energy mix (as far as I am aware?)
My solar diverter is me and a big fat switch next to the water tank.
If it's sunny I switch it on and heat up 315 litres. Enough to last three days.
That would do it! :-)
Great video thanks Gary. 😎 You’ve confirmed (with science) what I’ve been thinking about my iBoost diverter since I went onto the Octopus Flux tariff last month. The news about the carbon cost of generating the electricity we don’t export to the grid was a real eye opener. 🫣 My current strategy is fill my battery with as much power as it will take from 02:00 to 05:00 and get exporting as early in the day as possible. I’ll see how that turns out over the next couple of weeks. 🤞🏻Cheers. Mark
Hi Mark, loving the Max Headroom profile pic - takes me back to my college days! Happy to have helped you out - it's such a shame that diverters aren't worth it, as conceptually, they're a great idea! I like your strategy and I think you'll do well with it - my strategy will be the same, just as soon as I get my export MPAN :-)
Thanks Gary - I’ve just run the numbers for last week and the strategy not only paid for the electricity I imported but ALSO the gas 😎 If it wasn’t for the (insert curse of choice here) standing charges, I’d have made a £2 profit !! Octopus are really enabling micro generation and when it comes to setting you up for exporting they don’t drag their heals so I hope you can start to enjoy the benefits of Octopus Flux very soon too. Please keep up the great work you’re putting into this channel chap. 👍🏻 VBR&T Mark
@@Bushmaster101Green Yeah, the level of standing charges today is just crazy - particularly for those who don't use much energy - they're being penalised far more than anyone else. I'd much rather the standing charge was reduced to only that to cover the cost of the infrastructure, then the remaining items added to the variable costs (just like many other costs are today).
Great to see you're now saving (and hopefully soon earning) plenty cash - I'm just waiting for the G99 certificate to come back from SSEN then I can sort my export MPAN 🙂
I agree the burden of the faux carbon neutral agenda is going to be borne on the shoulders of the least able to pay for it. To quote Guns and Roses - ‘it feeds the rich, whilst it buries the poor…’ who can’t possibly afford solar, EVs, heat pumps, ground source or wind generation… 🙄
Challenge I have is that Intelligent Octopus is a no brainer if you have a EV, Solar and Battery (7.5 6 hours cheap rate vs 20p for 3), but the outgoing octopus rates can't be used with those. There seems to be a gap for folk who uses Intelligent or Go but who could export more.
Yeah, many people say it's to allow Octopus to derive some kind of revenue from Go and IO customers, but I agree; I don't see why a relatively healthy export rate could not be added to those tariffs...
Another interesting video Gary. Thanks for this, really valuable. Hoping I can follow in your footsteps with some of my videos about my solar install on my channel. Just starting out but can hopefully help a few people out like you are doing. 👍
Hi Dan, you're most welcome! I took a look at your channel and I really like it (have also subscribed) - good luck with your UA-cam journey - hard work, but well worth it :-)
@@GaryDoesSolar Thanks Gary. Appreciate that. 👍