What Size Solar Panel to Charge a 12V Battery 

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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

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.

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.

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

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.

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.

Thank u so much for sharing my friend. Truly 🙋

Thanks

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

Really good info there,, I'm considering a diesel generator to help top ups maybe 3 hours and thats a whole different beast.

Excellent,Excellent,Excellent. I can't say anything else!

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

Good info.

great video

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

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)?

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?

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

I need a advisor to help me

Is it OK to connect 2 100ah 12v solar panels in parallel to a 30Amps charge controller to charge a 75ah 12v battery?

Simple as would be good..

This is why real inverters like victron are better as they have far less parasitic draw.

Kindly can I know the name of this video editing software please

We have 27000Wp of solar. We had days where total production was less than 1kWh.

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.

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?

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.

You seem to be assuming, but don’t seem to have stated, that the system is consuming the entire battery capacity each day.

😊

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.

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..

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.

I feel dumb. I never thought about turning off the inverter.

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.

HEY YOU NEVER SAID HOW MUCH SOLAR CHARGES A 12V BATTERY WHATS THE ANSWER ?

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 AI that is reading the article should be set to clear up the speech patterns.

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.

This video is killing me slowly …

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