What Size Solar Panel to Charge a 12V Battery

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

[JoselitoRamirez-yb]

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

[JockoLeflur]

This is top stuff mate, the math and formulas are just bonza. Thanks for putting it out there.

[juancarlosamadomorales]

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.

[canyondan]

Great informational video. Thank you so much for sharing this information.

[taqarii]

I can't thank you enough for your efforts.

[jamewoods]

Excellent explanation, showing the use of the solar site, and very well put together. Thanks from Phoenix, AZ 101F weather

[RB-lfbo]

Thank u so much for sharing my friend. Truly 🙋

[joelquaintance]

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

[kylefrandsen]

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.

[zalllon]

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

[Fatfreddy]

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

[Janisg]

At my location (Latvia) annual average is 2.95 KW/m2/day. But in december only 0.36 KW/m2/day, november and January is also below 1 KW/m2/day. And that 0.36 is the december average, maybe 5 sunny days, and 25 cloudy days in december. In august it is 20 times more, 5.58 KW/m2/day. Solar is popular and pays for it self, but only in grid connected systems. If you wan to go offgried, you get 8 good months Martch to september. Februarry and Octobrer maybe. But November to January, there is almost no solar. Need grid, generator or maybe wind turbine. But almost nobody uses those wind turbines.

[a]

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.

[ztc]

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.

[billjones]

You are assuming we are unsung full available stored watts every day
In our camper we may only use it occossionally on weekends, then only for lights, water pu fan on occossion. We thus only red to replace part of charge drawn and may have several days to top off . Fewer batteries, less cost. I already have 1000 watt inverter, may only draw 85 watts to run my refrigerator in camper running 50% of time ?

[asifshuja]

Please tell how to Calculate the Solar Pannels with reference to MPPT Charge Controller interms of Voltage & Current Ranges

[darylcheshire]

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?

[osholajones]

Friend how many panels to charge a Tesla plaid using your sample City

[abrahamchairez]

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

[pasinduhasaranga]

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