How Many Batteries Do I Need? (How to Calculate the Battery …
You can also convert this into ampere-hours by dividing the kWh by the battery voltage. For a 12V battery, this will become 24 kWh / 12V = 2000 Ah. For Lithium Batteries. Battery Size (in kWh) = Average Daily Power Usage x 1.2 (for 80% DOD) x 1.05 (Inefficiency Factor) For our example: Battery Size = 10 kWh x 1.2 x 1.05 = 12.6 kWh