What Do Solar Panels Produce On Cloudy Days
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- Опубліковано 29 лис 2023
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Not every day will be filled with endless sunshine so the question is how much power can you expect from your solar panels on cloudy days? This is especially critical if you are designing your own system with batteries and are considering covering some of the worst-case scenarios. I will test out 3 different systems and average the output to get a percentage of rated power which will give you an idea of what you could expect on your solar system.
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Main two factors for cloudy day production are the cloud deck thickness and time of year.
There are many many other factors too.
Day 900+ off grid here and on rainy winter days I’m lucky to even get 1kWh total daily production out of my 7kW array. On rainy summer days that number is around 5-6kWh produced.
Really need a pyranometer for these types of tests.
Thanks for the video.
I have two systems my main system is 9.4kW and my SolarEdge system is 6.4kW but I don't really monitor it.
On the 9.4 kW system I just finished upgrading to bifacial models for a portion of it which is 4.44kW, I just bought 12 more bifacial PV to upgrade my other half of this system because on overcast days the bifacials do better than the standard modules and I live in the western Catskills of NY and we get a lot of overcast days here. I wouldn't think bifacials would give much benefit on roof installs though, mine are on ground mounts, the high point is about 10 feet off the ground and they are at a 42 degree inclination.
The thing is that I've noticed that there are different levels of overcast so it's hard to get a good measurement of output. Generally speaking I'd say I get about 1 to 1.3 kW on an average overcast day, the bifacials do help a lot.
Very interesting video!
I have 16 cheap 250 watt used san tan solar panels and when I lived in Pueblo (Colorado) they did ok even on a cloudy day. Probably around 30% (of what I would get on a sunny day not standard test conditions numbers) . Wasn't cloudy much and very little humidity or particulates in the air. I am now in south central Oklahoma and on a cloudy day I get about 20%. And tons more cloudy/humid days. Lucky my load is lower here so the system still does pretty good. Not bad for old panels.
I only have 330 watt system. I get about 5% on cloudy days. I use the 3 finger system. Hold up my hand and can count my fingers in my shadow, then I can expect 75-100% of rated output. Otherwise I get very little.
Very true. I get only 1 insolation unit during June July. The panels drop to 5 or 10% . Makes my systems very large and expensive
Those were some cool setups! I just got a Tesla system installed last winter and have been having a fun time exploring the app. Out of curiosity I really tried to drill down into what was affecting the maximum output on different days, and in addition to the cloud cover and time of year, I'm pretty sure I've been seeing effects from temperature and even windspeed as well. Very cool stuff!
Yeah, the temp will have a significant impact. 👍
Good info.
Thanks!
I picked up (2) Rich Solar 200 w panels last year. I did this because i wasn't 100% sure where i was going to put my pa els when i got the system i wanted. I figured I'd play around with 2 cheap panels for a while to help decide what panels i needed where. The absolute best output I've ever seen was 305 watts. In cloudy conditions, I'm getting less than 10 watts.
I have 5.5KW off grid solar inverters, and they word well. NICE!
Well, you have an enphase system, it would be cool if you just posted a picture of it with "Month" selected that shows each day's generation for 30 days or so. That gives you 30 full-days-generation data points to show people that will include sunny, party cloudy, cloudy, and probably some rainy days too yes?
For example, when I look at my brother's system for November, the sunny days run from 21 kWh to 18 kWh as the month progresses, and the cloudy days run mostly in the 13 kWh range with the worst day generating only 3.6 kWh. So at least for his system, the worst day's generation was around 18% of what he would get on a sunny day during November. And the system average for the whole month was considerably better than that.
I don't think there is much of a point looking at a few wattage samples. What matters is the whole day's generation.
Thanks for the feedback and I agree that would have been a great addition. Here are some of my numbers and I did have 1 day where basically nothing came in.
My system was commissioned on Nov 1, 2023 so just closed out the first month. Nov 20, 21, 22 was a rough path with 6.5 kWh, 3.5 kWh, and 8.5 kWh respectively. My worst day was Nov 26 only putting out 0.5 kWh and had numerous days around 55 kWh. Thanks so much for the feedback and suggestions.
@@everydaysolar Great! Thanks for sharing that! I think winter data can be quite valuable, particularly for people who are also adding battery storage and need to figure out what a comfortable amount of storage would be.
Your brother must not live in a very cloudy area the. For me, highest sunny day production of 4.0 kwh is more like 0.15-0.2 kwh on pure cloud days (not rain). So, 20x more capacity on a pure sun day than a pure cloud day, or pure cloud day is 5% that of a pure sun day.
@@HandfulOfTranquility Well, I don't think a single month's worth of data really says anything about the greater regional weather patterns, though its certainly better than taking a few data points on a single day. But this is why it is important to look at the big picture, even multi-year data, when sizing both the solar array and the battery storage.
It isn't possible to cover every situation, but it is possible to size systems to be able to bridge a few days of bad weather book-ended with a few days of sun, greatly reducing the generator run time needed.
Hard to calculate with any accuracy because cloud density would cause vastly different current readings.
What about Polycrystalline vs mono crystalline ?
Would linking in parallel instead of series give better results?
On a fully overcast day my EcoFlow was showing 0 input on 400w panel. It is about to snow though so when the sun was behind clouds it was very dark thick clouds
Yeah, the panel voltage probably dipped under the minimum voltage for the Delta Pro solar input. If you put 2 panels in series you might get a bit to come through on a cloudy day without hitting the lower voltage limit.
So far, My 10.3 kw system has a daily low of 2.0kwh(Nov 21st) and a daily high of 56.6kwh(Aug 19th) since Aug 1st. Huge range. I am starting to hate rainy days, from a Solar generation point of view. The max I have seen so far is 7.1kw, 69% of my system. Thanks for the video.
Thanks for the feedback and my system was commissioned on Nov 1, 2023 but I have similar numbers. Nov 20, 21, 22 was a rough path with 6.5 kWh, 3.5 kWh, and 8.5 kWh respectively. My worst day was Nov 26 only putting out 0.5 kWh and had numerous days around 55 kWh. Thanks so much for the feedback.
Nov 21st is when we started using our same power (10.26kW, bifacial, near perfect orientation, Lithuania) system, and the lowest so far was 0.4kW yesterday, due to snow+snowing. It does not seem the sun will come out more than a few times in all December, so it takes days for the snow to melt off when overcast. We can clean it if we want to get a few kWh per day (makes sense only when better weather is expected). And in general, the generation is VERY spiky, from near nothing when panels are under the snow, to 1-5kWh in overcast day, to spikes of production of 5kW+ per hour if the panels are clear and sun comes out (it almost never does, and it is low now, only gets to a ~12-13 degree altitude in December here). Most generation will have to happen in spring-summer, when days get 16-17h+ long. Then, net-metering will allow to 'accumulate' for next winter use at a rate of getting 88% of exported kWh back for free.
Hi I would like my house mini inverter 5600w installer direct ac plug and play ist possible
Thanks for the video. I see you created an average for the test points. I am surprised it was so low for a cloudy day. I suppose that means if you get a lot of cloudy days it might mean having to severely oversize the total system.
Yeah, I think looking at some of the worst case scenarios becomes very important when designing an off-grid system. Most people would just have a natural gas or diesel generator for the few times per year that you string together more than 3 days in a row with clouds/rain.
@@everydaysolar I agree, and you should always have some backup system, at least for the fridge
@@everydaysolarFEW times a year?? OK, DRUG ADDICT!!!!
hello ，would you have interested in testing our foldable solar panel ?
🤔 S. Fl. No problem....
It is cloudy here today, the highest my panels reached 120Watts, on a sunny day the highs will be around 2200Watts, so that's 5.45%. The maximum my panels can produce is 2700W, so I got 4.4%, so we will call it 5% on a cloudy day, and 82% on a sunny day
Nice, thanks so much for the feedback and those numbers are very similar to what I am seeing in the first month of my system being up and running at my house.
4-5%
The issue for some people they made massive investments, and this is not an odd cloudy day, is Just a Regular Day 😳 the Odd & rare day is when it's sunny & not a single cloud in sight
How many times that happens in 1 year 🤔
Yeah, I think the truth is somewhere in the middle and closely tied to what part of the world you live in. PV Watts will pretty quickly give you an idea of your potential solar output on average per month.
Industries & youtubers will have you believe this is a Freak & Odd day, in fact is just a Regular day 😳
I have taken a lot of data on solar panel output versus sky conditions. The solar panel rating is based upon idea or slightly better than best-case scenario. The rating assumes the panels are perfectly aimed towards the sun, the sun is directly overhead (high noon), the sky is perfectly clear, humidity is low, the temperature of the panels is +25 degrees Celsius/+77 degrees Fahenheit, the rated power is being measured at the panel terminals, and the panels are brand new. Any kind of cloudiness quickly drops the panel output. For instance, if the day is bright and sunny, with an occasional white puffy cloud passing in front of the sun, panel output drops about 75%. On the maximum end of cloudiness, if a severe thunderstorm is about to strike, panel output drops about 99.5%. In both cases of cloudiness mentioned here, the sun is within +/- 2 hours of high noon.
Add to these losses are the system losses: wiring voltage drop, solar controller loss, power inverter loss, battery charge loss (this assumes off-grid, grid-tie would not have the battery and solar controller losses). In short, with off-grid, you get about 50 to 70% of the panel power converted to house power. With grid-tie, it is 80 to 90%.
Thanks so much for the feedback and sharing your experience. 👍
Hello we have attempted to fix/ upgrade our solar system to accommodate our family to no avail. We are Army Veterans that decided to move totally off grid with our 3 kids. Despite our efforts we have problems when we get very little sunshine. It seems the batteries aren't charged enough to take us through the night. On an average day the sun would have charged our system and the inverter will go into the night displaying 50 volts. However, during a heavy rain we had 2 days ago that started at 9am and lasted all day, we went into the night at 44 volts! By midnight the alarm was sounding on the inverter and the power went off shortly thereafter. We also have this issue when we attempt to turn on the air conditioning...using it too close to sun down can cause the same issue. I was thinking we need a larger battery bank but someone told me I need more panels. Honestly I'm confused. Please help.
Hey Ronald, join the facebook group (Everyday Solar) and we can dig in a bit more. Once you get in the group just post this same questions and also any pictures and specifications of the setup. Thanks!
Thanks! I will do that!
What are those legs on the 100w panels?
Little built in legs for the 100W thunderbolt panels from Harbor Freight
I had read in a scientific solar article a year or so ago that a solar panel with good efficiency (21-22% efficient) can produce about 10% of rated power on even a full overcast day so your percentages may be a bit off (low) but you are getting the point that even on a dreary cloudy day the panels can produce power.
On overcast days the optimal angle moves to flat as the cloud cover increases according to the masters thesis I read the other day.
Could be the reason for a discrepancy.
I wonder if it's worth the effort to make the racking interactively adjustable to take advantage of this.
Of course it would somewhat depend on local climate, not likely worth it in AZ but maybe it is in the north east or mid-west.
Thanks for the feedback guys!
I have a 6kwh (2x3 at 370v) array especially for cloudy weather, a very shallow angle works best, pretty much 10 to 20 degree tilt. It captures maximum diffused sun from the clouds.
Yeah I just read a thesis that said in full overcast the optimum angle is flat.
@@ghz24 I had to tilt a bit so water / leaves / bird crap would wash away
@@MoaningGit Yeah just because it's optimal doesn't mean it's worth the trouble of persueing it.
It's nice to know where the optimums are and how much tradeoffs cost though.
@@ghz24 I'm lucky to have free solar panels and equipment, otherwise you're correct.. it's really not worth it
@@MoaningGit I had to buy mine but it made sense to get a full pallet so I have a few extras to play with. I want to test vertical orientation on a south wall in the winter.
I was expecting basically zero percent production so better than expected.
It is better than nothing, and it is the same when it is raining, unless it is heavy rain, and the sky is dark
my friend,it doesnt matter how small ammount of energy we get from solar panels in winter it is god that we have some energy for free,for me one light builb is fortune iin winter time because i live in forest away from city..
How about 14.6 kW Bifacial ground mount solar array, EG4 18 k inverter/charger, 32 kWh Lifep04 battery with 2 amp active balancing BMS and a EG3 Chargeverter all for $16.000. and our system still works when the Grid is down.
Cut almost everything in half and that's what I'm building (except no chargeverter). Sounds like a system with a reasonable payback time. Is it a stand alone?
Only missing a solar minisplit to look like a big brother of mine.
Have you looked at the eg4 solar minisplits?
yes stand alone. I have looked at the mini split but not for this property. when we build the new place we will get it.
I am installing a Mr Cool 18,000 BTU minisplit today and tomorrow in that detached garage (in the video) and will run it off 2 EcoFlow Delta Pros. I would like to compare that unit with a EG4 solar minisplit to see how much you can save running straight DC.
@@everydaysolar To me it's a way to use 4 more of the solar panels I bought without needing more inverter and battery to utilize it. I need a good efficient electric heater anyway and I'm tired of lugging my window AC to/from the shed every 6 months.
And since the solar electricity never actually "enters the building" there are several local codes that are completely avoided.
Besides free AC when the sun shines will keep a smile on my face for a long time.
I think they are one of the cheapest ways to start using solar. $1300 for the pump $4-500 for panels $300 for a ground mount.
$2500 for many people would have a very quick payback depending on present heating system. They will pull from the grid to make up for insufficient solar or to run after sunset.
I'm pretty stoked about them. Hope I like them as much once I have one.
on cloudy rainy days I'm lucky to get 20 percent
Oh yeah, 20% would definitely be on the high side for me
As soon as I saw the video with the clouds and the lighting I made the guess of 8% of rated capacity.
Really depends on that power point tracking to some extent, but I was pretty confident in my diy experience to say 8% right off the bat.
1/10th - 1/100th of rated power its misarable
thin film panels are better for cloudy conditions...just sayin'
simple solar value calculation. presume 1000kWh annual power for each 1 kW solar installed. Lots of public data, you need to know how to interpret for your area, but this works for almost all latitudes say above 40 degrees. Know your cost of install per watt. Example 10kW instaled for $3/watt = $30,000. Life expectancy if everything works perfectly, 25 years. 25 year mortgage calculator shows $30,000 would be $200/mo for 25 years(depends on rates). If your grid power cost is 10c/kWh and your 10kW system can earn 10,000kWh/yr x .10c/kWh = $1000/yr while annual payments are $2000/yr as shown above. Inverter life expectancy 10-12 years, solar panels degrade making less power every year, solar panels can fail, etc. Payback....if you are cashing in investments that should be earning you at least 6%/yr, I suggest you leave your money invested. And watch out for solar salesmen and their claims.
Panels cost $0.17 per watt. Just got 455w panels for $80 a piece. 10kw worth of panels would cost $1700. A 10kw Deye inverter is $2500. With wiring and fuses you would be looking at $4500.
looks like you sell solar systems, can you install for 45c/watt? As above? Normally $2/watt or more or $20,000. Can you install 10kW of solar for me for 45c/watt? @@alexgunner1882
Not much. Plan accordingly.
you have no idea how the bms works
True
EcoFlow Delta Pro? You've got to be kidding. No experienced off gridder is going to use a low cost, high frequency, transformerless inverter charger like a EcoFlow for their residential application. With over 24 years of experience in the inverter repair industry, we know full well that the vast majority of low cost, lightweight, Chinese made, high frequency inverters on the market simply don't last. Especially when powering inductive loads like refrigerators, microwave, ovens, portable air conditioners, power tools or motors. You may be able to start some of these loads when your high frequency solar generator is new, but over time, typically after less than a year of repeated use, powering high inductance loads, your lightweight, high frequency solar generator WILL fail. They simply were not designed for powering inductive loads. That's why the big name brand inverter manufacturers like Schneider Electric, Outback Power, Magnum Energy, Sigineer Power, Victron Energy and others, all use a low frequency topology in their design.
Good stuff, thanks for all the feedback. I want to actually put these units to the test so I will be powering a detached garage with mini split and a few other loads off 2 x Delta Pro with dual voltage hub and then the small house off the Delta Pro Ultra. Should have some real world tests adding up soon.
I've been using the same two high frequency inverters wired in parallel for 4 years, powering 2 air conditioners, a refrigerator and a separate freezer, a microwave, well pump, induction cook top, welder, table saw, grinders, etc., So far so good...They are the all in one units with the built in solar charge controllers, each can handle 500 volts and 6000 watts of solar. and are 6000 watt inverters..They are not solar generators but are high frequency inverters..
@@realeyesrealizereallies6828Thanks for your comment. I went with a 3000 watt version of the same inverter (sounds like) haven't tested it yet.
You would have only needed to buy one low frequency inverter to accomplish a longer life expectancy and surge capacity. By wiring two high frequency inverters together in parallel you effectively doubled the surge capacity.of the MOSFETs in your inverters and increased their service life, but at a cost. Please come back in a year and let us know if your high frequency inverters are still working. Thanks. @@realeyesrealizereallies6828
@@ghz24 I have a few yellow 3000 watt inverters for cabins that I rent out on AIRBNB, haven't had any problems with them either, but they have only been running for two seasons...They are solid, if that is the color your referring to...