Some things to note:
1. Lithium batteries have a Depth of Discharge at around 80%, so we will work with 80% for this calculation.
2. Whether you connect your batteries in parallel or series the total energy remains the same. 2 12v 100Ah batteries will always give you 2400Wh.
Formula for calculating total usable energy of the battery bank:
(Depth of Discharge) × (Total Bank Energy)
(80÷100) × (2 × 12v × 100Ah) = 1920 Wh
Formula for calculating solar array required to charge the batteries:
Minimum solar array required = (Usable battery bank energy × 1.3) ÷ Peak sun hours
Please note; peak sun hours is not the same as hours of sunlight received per day.
We multiply by 1.3 as a safety factor to account for all the inefficiencies.
Let’s calculate the solar array needed;
Minimum solar array required = (1920 × 1.3) ÷ 5(peak sun hours) = 499.2w
Formula for number of solar panels:
No. of solar panels = Minimum solar array ÷ Panel rating
No. of solar panels = 499.2 ÷ 250
No. of solar panels = 1.9 ~ 2 (you round up to the nearest whole number).
Peoplesmind
