What Size Solar Panel to Charge a 12V Battery
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- Опубліковано 5 сер 2024
- 🎁 Free diagrams: cleversolarpower.com/free-dia...
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Link to sunhour tool: pvwatts.nrel.gov/
In this video, I dive into the question: How many solar panels are needed to charge a 12V battery? I provide guidance and calculations to help you make informed decisions for your off-grid solar system.
The analysis begins with a deep dive into a 12V 400Ah lithium battery, followed by a detailed calculation of its total power capacity. We then examine solar potential in Houston, Texas, during the winter months, crucial for planning solar panel requirements.
Discover the considerations between polycrystalline and monocrystalline solar panels, and explore unique calculations for lead-acid batteries. Gain insights into the efficiency factors of lithium and lead-acid batteries, as well as charge controllers, to optimize your system.
We also address inverter losses and idle power consumption, often overlooked but essential factors for off-grid solar systems.
Whether you're an experienced off-grid solar enthusiast or new to the field, this video equips you with the knowledge needed to make informed decisions for your solar setup.
00:00 Introduction
00:30 John's case Lithium
01:57 Formulas
02:19 Mono or poly panels?
02:45 Lead-Acid
03:22 Efficiency
04:44 Free diagrams
04:59 Inverter losses - Навчання та стиль
🎁 Free diagrams: cleversolarpower.com/free-diagrams/
📖 My best-selling book on Amazon: cleversolarpower.com/off-grid-solar-power-simplified
💵Use coupon code: clever6 to get 6% discount for Litime batteries: cleversolarpower.com/litime (cheaper than amazon)
Your information is really helping me to understand more about this subject because I live off grid 100% depending on my electric solar system. THANK FOR YOUR VIDEO Iam suscribed to your channel
Great informational video. Thank you so much for sharing this information.
I can't thank you enough for your efforts.
This is top stuff mate, the math and formulas are just bonza. Thanks for putting it out there.
My pleasure! More coming up
Thank u so much for sharing my friend. Truly 🙋
Gracias mi amigo tus diagramas me serviran de mucha ayuda.
Thanks my friend your pdf diagrams help me a lot to design my 2kw off grid solar system.
Greathigs from Guatemala.
Glad you find them helpful!
Really nice work and video you did. Electricity is like Black Magic. Solar batteries and panels Parallel vs Series is another subject depend the needs required.
The main thing to remember is that wiring batteries in series will increase your voltage, while wiring in parallel will increase your amperage.
Thanks, through videos like this I'm trying to make it understandable.
Thanks
Excellent,Excellent,Excellent. I can't say anything else!
For me it was easy, as many panels as I could fit on the roof of my van :) 4 320w panels +100w panel (to charge the start battery). I also have 5000W/h battery bank with 24v and a 3000w inverter.
The panels is mounted flat and I am very far north but still the flat mounting works ok, and flat mounting seems to give more power then other report is usual when it is overcast and raining. Max power in middle of sunny day I get is 1000w from the 1380w of panels, overcast days it is 270w or so with thick cloud layer or rain.
Really good info there,, I'm considering a diesel generator to help top ups maybe 3 hours and thats a whole different beast.
If you live up north, a generator definitely helps during the winter months.
This is great information, especially the PV website. Now I have a more reasonable understanding of how many solar panels I’ll need for my shed workshop. Initially, I was trying to maximize the amount of panels I had on the shed roof, only to find out that over a surface area of 5 m² I would need a building permit. I was going to put up some used panels which are actually working very good that I got off Kijiji, which would give me about 1300 W, and put me over the surface area of 5 m². But now with the calculation here, as well as the PV website for my area, and me having 2x 100A LiFePO4 batteries, I need about a 400 W array size. If I double the amount of batteries, and since I’m only in my work shed on weekends, then, potentially the maximum I would need is 800 W, and that keeps me under 5 m² of surface area, where I can avoid having to hire a structural engineer, and needing to get a permit, so this saves me quite a bit of headache and money. if I do run out of power, I can always drag in a 2 kW EcoFlow power station that I have
A permit for 5m2? wow... I have 6,4m2 with 4 320w panels on my van, that is insane that you need a permit for that small solar array you can fit on the roof of a van. And needing a structural engineer for mounting 60kg (that is what mine weigh) on the roof is equally insane.
Thank you. As I'm looking into solar for my whole house, one thing I'm also factoring is the positioning of the panels. Since my roof isn't facing directly south and isn't pitched at the ideal angle, I may only get 70% of the rated wattage even under ideal weather conditions. If your example is in Houston during the summer, temperature may also reduce panel output. I guess I would use your calculations as the bare minimum and then add panels to make up for the rest.
I get 70% of max power on my flat mounted 320w panels on my van, and on overcast days it seems the flat panels actually give an advantage? (I get more power on overcast days then I hear other with optimal angle get).
@@a64738 I have an L-shaped house, so I bought some cheap 100 watt panels and "solar generator", threw the panels on each angle for a week and recorded their output so I can get a baseline and determine a layout that works for my needs - all on one side or some on each side to get a lower, longer peak power curve.
Good info.
Glad it was helpful!
great video
Thanks!
Friend how many panels to charge a Tesla plaid using your sample City
I need a advisor to help me
For a quick rule of thumb, just take the nameplate wattage of the panels and multiply by 2 to 3 in the winter, or 4 to 5 in the summer.
That's it. So if you have say 4 x 100W panels, that's a nameplate of 400W. For winter that will be 800Wh/day to 1200Wh/day. And for summer you end up with 1600Wh to 2000Wh/day of energy.
When sizing a battery, you always want to have more storage margin than your best-case generation. Usually at least twice. So using the above example, you would want roughly 4000Wh of battery storage. With LiFePO4, that's one 5kWh rack-mount battery, one big truck battery, or two normal car-style batteries.
The reason you want to have more storage margin is to be able to buffer extra energy on sunny days that help you bridge cloudy days, and be able to catch-up when the sun comes out again. The amount of storage required to bridge more than one day can be enormous, so having a goal of "2 days" worth of generation is a good rule of thumb.
There are no minimum charge rates for LiFePO4 (or any battery, really), and having more storage also means the battery bank will last longer because it will only be cycling 50% every day instead of 90% or more.
People also often vastly underestimate overnight consumption. Having more battery storage makes managing the system a whole lot easier. For example, in horrible conditions where you get no sun you would only need to run the generator for a block of time once a day or once every two days. Instead of several times a day.
-Matt
Yes, checkout my video about sizing a solar system with days of autonomy. It's impossible to say everything in one video, and I would be repeating myself.
I'm 'green' on what is available on BMS/inverter market, and have this question: what would be an economical way to convert my current grid-tied, non-hybrid inverter+10kWp solar system, into one with batteries? Solar panels are connected all in serial, so ~800V comes into the house, where the inverter stands. The inverter likes 400-800VDC for most efficient operation. I'd prefer to build the battery from cells (instead of buying a prebuilt one), starting with maybe just ~5kWh capacity. Is there a way to have cells work with this high voltage for cheap (even if it all stays grid-tied)?
I think the best option for you is to keep the string inverter and use an AC-coupled system. When the grid fails, you can still draw power from the battery with a victron multiplus on essential loads. This is my system. Send me an email for more information.
Hello, I have two 6V batteries. I run in parallel for a total of 225 amp hours would a 100 W solar panel charge them or would a 200 W solar panel be better
I use a 100W panel to charge the start battery on my van... For the living part in the cargo room I have 1380w of solar panels on the roof. A 100w panel is very little but it depends what you plant to run with it? For me it was to run a fridge and a freezer even if you get weeks with no sun in overcast weather, under those conditions my panels only give 270w.
Simple as would be good..
Is it OK to connect 2 100ah 12v solar panels in parallel to a 30Amps charge controller to charge a 75ah 12v battery?
You mean 2 100W 12V solar panels. Wire the panels in series and select the correct charge profile for the battery type you have.
Yes
Isn't there a video out there that just shows you amount of battery needed per solar panel? instead of a how to do the math video? OMG
That would not be accurate because locations have different sunhours.
Bro says 25 seconds in that it’s gonna be a detailed calculations video and you’re complaining that it is indeed a detailed calculation video lmao
Karen.
I need some help I'm buying an AC unit Media 6000 btu 535 watts. The specific are on Amazon with all the unit data. How many 12V. 100 amos batteries do I need I'll be buying lead batteries. And I'll be buying 800 watt wind power generator. For continues use. Would a 7000 peak an 3500 watt inverter be enough to hold the watts on a 535 watt AC. Thx
I do not know about AC but a fridge typically use around 1500w when it starts for a few seconds. So a 3500w inverter should be more then enough to run it (starting it is the hardest part and inverters usually are able to give double effect for a few seconds). For running it when started you would only need a 600w inverter, but as you I said you need larger to make sur it can start.
Is it true that higher watt inverters use more power, for example, using a 3000W inverter on a TV, say 250W, will a 3000W inverter use more power than an inverter rated closer to the example, say a 500W inverter?
Yes, bigger inverters have a higher idle consumption.
@@cleversolarpower My 3000w inverter have extremely low idle consumption (so low that I do not bother to turn it of when not in use), what is more interesting to know is if it is less efficient at reduced effect of for example 500w then 800w inverter ... I have not found any data on that anywhere. It only say the efficiency is 96% or something like that at full effect I assume.
Kindly can I know the name of this video editing software please
Let me know if you get it please
Videoscribe
Videoscribe
I live in Belgium where in december we have 0,56 hours of sun. and i have a modular home which consumes 14 kWh of energy. I willl install a battery of 50 kWh (an old EV battery) How many solar panels do i need to cover 3 days of energy?
14 kWh a day
Ah! Fellow Belgian! Your home consumes 14kWh of energy, so for 3 days of autonomy, you need 42kWh of battery storage. You need: 42kWh/0.56h=75kW of solar panels. This is not feasible. So if you are grid connected, charge a smaller battery with the max amount of solar panels you can get on your roof. If you are off-grid, use a generator in the winter.
😊
We have 27000Wp of solar. We had days where total production was less than 1kWh.
Unless it was covered by snow I would check your wiring ;)
so for people to under stand. power loss of a system can go as 50% of a cheap system. so you would have to double the size a salesman tells you. but you wont find out until you done invested half the money. so most people dont understand what they are buying. the battery system above will run a hot plate for about a hour. not bad for 5K.
Most people will be limited by how many volts that their solar charge controller can handle..A 12 volt system can handle half of the watts of a 24 volt system..And a 24 volt system can handle half the watts of a 48 volt system..And with the new all in one 48 volt inverters, most people should probably go with 48 volts these days, for a variety of reasons..But not everybody..
I'm making a video about choosing between, 12v, 24v, and 48v at the moment. Coming out soon.
You seem to be assuming, but don’t seem to have stated, that the system is consuming the entire battery capacity each day.
That's the point that this video shows.
You should add another "system efficiency" for the atmosphere. If you're near the ocean, downgrade by a factor of 0.95. If you're on the Mojave desert you can use 1.0.
A lead acid battery does NOT require "less" power to recharge. A 100Ah AGM is equivalent to a 200Ah LifeP04 in terms of useable power, assuming you only bring the AGM to 50% DoD but allow the LifeP04 to fully deplete. Charging both back to full would take the same amount of solar power. At 3:00min, one example has useable power of 5120Wh and the other only has useable power of 2400. Of course the one with less than half the useable power takes less solar to charge....
In your 2nd scenario, of course the battery takes less time to charge up, because you're comparing apples to oranges. Useable power is the priority, not the amp hours on paper. Additionally, all lithium batteries charge faster than lead acid, which means that they can take advantage of short bursts of power much better than lead acid. With a high quality rapid response MPPT solar controller (Victron etc), a lithium battery will take MORE charge than a lead acid of any variety.
If you have identical batteries, they do, which is explained in this video. Yes, i have a video specifically about c-rate for charging and discharging speed.
@cleversolarpower If you have identical batteries they will charge about the same at lower inputs, UNLESS you only discharge one partially (the AGM). Your example is misleading. Obviously the AGM will be fully recharged sooner if you only discharge it halfway.
And if you have much higher inputs, lifep04 can take a higher rate and charge quicker.
This is why real inverters like victron are better as they have far less parasitic draw.
Indeed, they also have an eco mode. I use victron inverters in my van systems. It comes at a cost though.
@@cleversolarpower personally I hate the eco mode as it causes problems, like it won't turn on for LEDs and small devices, and can cycle (which is bed and dangerous) so while I thought it would be good in theory I found it unworkable in practice, but the unit consumes so little it really is no problem.
The main problem is all the copper in the inverter which is expensive!
Eco mode is generally a bad idea. It works in very few situations and can potentially damage equipment in other situations. I never use that mode on my little Victron inverter. In anycase, the vampire draw is virtually always just a function of the size of the inverter. What I do is put critical electronics and so forth on a small 600W inverter that is left on 24x7. It's vampire draw is only 7W. Big loads go on bigger inverters which can be switched on when the load is needed.
For example, if you have an RV you might want a big inverter dedicated to the kitchen area with a remote switch in the kitchen itself, allowing you to use a small inverter for stuff you want to always be powered, like the fridge (if it happens to be an AC fridge), computers, internet, LED lights, etc.
In anycase, when it comes to inverters, Victron is not anything special. Victron makes wonderful charge controllers and shunts but they are a bit dated when it comes to other types of equipment. It took them forever to come out with the Multiplus II, for example, and it is already outdated by things like the EG4 6000XP.
-Matt
@@junkerzn7312 I like the term vampire draw 😀. Indeed the eco mode doesn't register small loads. Same as with new fridges, the electronics don't work anymore because the inverter doesn't see it as a big enough load. Victron is good at starting inductive loads though.
@@junkerzn7312 The idle consumption on my 3000w inverter is according to the data sheet 2w... I see smaller inverters that it say use a lot more, the low idle was one of the reasons I bought that inverter.
Whatever it says you need, DOUBLE IT. Those panels are rated in a laboratory. Their output does not reflect real life use, even on a bright sunny day.
Figure 100w panel will get you about 2/3 of that output on a sunny day.
Sun hours is an accumulation of W/m2 per day. If you have 6 hours of sun at 500w/m2 then you have 3 sunhours. It is accurate. Try it over a month and divide by 30.
I feel dumb. I never thought about turning off the inverter.
Some inverters have an automatic detection when the inverter is not working, called power save mode. It will automatically turn off the inverter when there is no load detected. This can be disabled by default.
What about the efficiency rating of the solar panels, themselves? No panels actually output the rating applied to them under lab testing conditions. Most will only put out 80 to 85% of their rated capacity. Also, you didn't factor in ANY usage at all during the day? I like your videos. I like the graphics you use. The production quality is better than most. The problem is, you are usually explaining "theory" instead of presenting information someone could actually use in a real-world scenario.
I hope John didn't actually pay you for your recommendation.
As you probably know, there is more than 3.5 hours of light during winter in Houston. It's not dark after that. 3.5 hours is the total amount of sunlight at 1000w/m2 in total of the entire day. Can be 7 hours of light at 500w/m2. In off grid systems, we calculate according to the loads, I have made a video about that on the channel. The solar panel then has to recharge the whole battery in one day. That's what this video is about.
@@cleversolarpower - So, in addition to not explaining that solar panels don't actually generate as much PV output as the number on the label, or mentioning that someone might actually be using power during the day, while the sun is trying to charge the battery, you purposely understated how much solar potential there is, and that's why we should just have faith in the information you're providing. Be accurate, be thorough, be transparent...or don't present videos as though you know what you're doing.
@@jasonbroom7147 I appreciate your critical review. As i mentioned in the video, all you have to do is research the sunhours per day for a specific month. I suggest you read my previous answer as to why that is or make your own video presenting the topic.
HEY YOU NEVER SAID HOW MUCH SOLAR CHARGES A 12V BATTERY WHATS THE ANSWER ?
Have you watched until 2:00 ?
You never actually answer the question do you? What size solar panel to charge a 12 volt battery? Lets say you are in Houston and the battery is lead acid. I want to decide on the size of the solar panel and it's specs.. What size panel? At what watts at what voltage? Still don't know.
The question is how many Ah your battery is. This is different for everyone. You can repeat the calculations for your own battery. It's easy.
@cleversolarpower sorry, I have a sever case of adhd. I purchased a 220 watt foldable solar panel, a 7000 watt (peak) inverter, and I am still . super confused on the battery. Am I able to use a 12 volt battery with 8, 12 or 26 ah, or is that ah too small & not work?
@@naidamaraja3640 It is impossible to answer your question without knowing what you want to power with this set. But tentatively answering - a foldable 220Wp panel is far too small in relation to the power of the inverter you bought.
@@naidamaraja3640 7000w peak I will assume means it is a 3500w inverter. To run that inverter at 3500w it will use 265 Ampere from the battery at 13,2v meaning that if you are running a LifePo4 or similar lithium battery you will need three 100AH batteries (that give 100A max) and that will be able to run the inverter at 3500w for about 1 hour before it is empty. 26ah battery is way to small you need much larger 300Ah or larger to run that huge inverter at full load. A 26Ah battery will only be around 300w hours meaning it can run 300w for one hour.
The AI that is reading the article should be set to clear up the speech patterns.
Thanks for assuming I'm an AI David 😄
This video is killing me slowly …
This is why I really don't use whole house solar power as it's not efficient nor does it even really save you money unless you get it for free or received subsidies from the government to cover the expense or take you 15 plus years to even see any returns.
Hahahah you really don't know what you're talking about.
Installed 5KW direct consumption solar myself for around 3K€
I'm paying 0€ per month in electricity now. Return will be in only 4 years.
@@encostablanca You also don't live in America as you don't realize how much our homeowners insurance will go up the minute you put a solar panel on top of your house. I've had several neighbors in my neighborhood that had to remove their solar panels or they would lose their home when their mortgage company foreclosed as they couldn't get insurance. Different situation when we pay over $10,000 a year for homeowners insurance. You do the f**king math.
@jamesm568 you don't have the space on the ground?
@@thegreatone11 It would take up a significant part of the backyard, but then you have to deal with shadows from the trees. I already did the math already as there is absolutely no benefit unless you get solar at a significant discount from the government or buy it already installed on the home. I've also talked to my neighbors and they haven't seen the financial benefits in over 10 years for the ones have solar except for insurance companies threatening to foreclose on their homes because they lost their insurance.
@@jamesm568 As you know, the USA is not the only place in the world. I would also not be surprised if insurance regulations and costs vary from state to state. Please don’t knock the whole concept simply because of your own particular circumstances.
THIS IS NOT A SUSTAINABLE WAY FOR ENERGY THOSE PANELS ARE TOXIC WITH NO WAY OF RECYCLING ITS A FARSE REAL SUSTAINABLE ENERGY WITH NO BY PRODUCTS IS ZERO POINT ENERGY