Before choosing the size of the solar panel we need to be clear about how big the 100ah battery is, 100ah means that the battery is discharged continuously for 100 hours at 1A current or 20 hours at 5A current and 10 hours at 10A current, if it’s a 12volt 100ah battery according to Power=current (amperage)*voltage (volts), there are a total of 1200 watt-hours of power that can supply A 120w device to run for 10 hours. The solar panel will not charge the battery directly through the charge controller, so the power size of the solar panel can charge the 100ah battery, to choose the right solar panel.
100ah battery is often used in outdoor camping, full need to understand the battery voltage, there are 12 volt, 24 volt and 48 volt, 12 volt 100ah battery for 1200wh, 24 volt for 2400wh, 48 volt for 4800wh, a 10w solar panels to fill up the 1200wh battery need 120 hours which is obviously unreasonable, if the day’s If the peak sunshine duration of a day is 4 hours, a 300w solar panel can fully charge a 12 volt 100ah battery in a day, of course you can calculate to other batteries to buy the solar panel you need. First of all your expected peak sunshine duration is 3 hours, you need to know the battery voltage is 24 volts and the battery capacity is 100ah, then the battery capacity can be expressed as 2400wh, so you need 800 watt solar panels to be fully charged in 3 peak sunshine duration. Of course the peak sunlight hours does not mean that the actual time for 3 hours affected by various reasons more than 3 hours.
(1) Solar Charge controller, the choice of charge controller is related to the charging of the power loss of the maximum increase in the charging speed of the charge controller must choose MPPT, can make the charging power is always at the maximum speed.
(2) solar panel efficiency, the type of solar panels solar hard and soft panels and folding panels according to the manufacture of different into monocrystalline silicon and polycrystalline silicon, amorphous silicon. Efficiency between 15% and 25%, the choice of monocrystalline silicon solar panels are generally about 23% efficiency This is the fundamental power conversion of solar panels power in the actual charging time has a high gap.
(3) increase the number of solar panels, for example, a 300-watt solar panel in four hours can be 12 volts 100ah battery full then prepare four 300-watt solar panels to increase the power generation can reduce the charging time.
(4) depth of discharge, for 100ah battery for lithium batteries and lead-acid batteries of different types represent different types of discharge, although the rated capacity are 100ah but the real charging is also related to the depth of discharge, for 50% of the lead-acid batteries for the real usable capacity of 100 * 0.5 = 50ah, for the same solar panels and the real charging of the expected charging time and the real charging of only Expected 50%, lithium battery depth of discharge degree of 80%, the same charging time is only 80% of the expected. Lead-acid batteries require less power than solar panels but lead-acid batteries use less power.
For 12 volt 100ah lithium batteries should be charged with a 300w solar panel.
For 12 volt 100ah lead acid batteries should be charged with a 150w solar panel.
For 24 volt 100ah lithium batteries should be charged with a 600w solar panel.
For a 24 volt 100ah lead acid battery it should be charged with a 300w solar panel.
A 10w solar panel can charge a 100ah battery but it will take a long time, a 1000 watt solar panel can also charge the battery but considering the time and damage to the battery a 12 volt battery with about 300w is fine.
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