Pretty much any solar panel will be able to charge a 100Ah battery. It just depends on how long it will take. Here are some examples we calculated along the way: A 100-watt solar panel will charge a 100Ah 12V lithium battery in 10.8 peak sun hours (or, realistically, in little more than 2 days, if we presume an average of 5 peak sun hours per day).
A 10kW solar system will charge a 100Ah lithium battery in 6.48 peak sun minutes. That’s quick! To adequately calculate the size of the solar panel to fully charge any 100Ah battery, we have to take a 2-step approach.
100 watt solar panel will take about 9 peak sun hours to fully charge a 12v 100ah lead acid battery from 50% depth of discharge. 100 watt solar panel will take about 16 peak sun hours to fully charge a 12v 100ah lithium (LiFePO 4) battery from 100% depth of discharge. How Long To Charge 100ah Battery With 400 Watt Solar Panel?
To charge a 100Ah lead-acid battery, you’ll need a 3-6 watt solar panel. To charge a 12V 100Ah lead-acid battery from a 50% depth of discharge using a PWM charge controller and assuming 5 peak sun hours, you would require approximately 270 watts of solar panels.
As we can see, a 400-watt solar panel will need 2.7 peak sun hours to charge a 100Ah 12V lithium battery. If we presume that we get 5 peak sun hours per day, we can actually fully charge almost two 100Ah batteries (or one 200Ah battery).
The size of the solar panel needed to keep a car battery charged depends on a variety of factors like the solar charge controller type, depth of discharge, battery type, and desired charge time in peak sun hours. To charge a 100Ah lead-acid battery, you’ll need a 3-6 watt solar panel.