CALCULATE HOW MANY SOLAR PANELS THAT WILL CHARGE 2 12V 100AH LITHIUM BATTERIES

### Important Points:

1. Lithium batteries typically have a depth of discharge of 80%, which we will use for calculations.

2. Battery energy remains constant whether connected in series or parallel. For example, two 12V 100Ah batteries yield a total of 2,400Wh (100%).

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### Formula for Total Usable Energy:

(Depth of discharge) × (Total bank energy)

Example:

(80 ÷ 100) × (2 × 12V × 100Ah) = 1,920Wh (80%)

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### Formula for Solar Array Size:

Minimum solar array required = (Usable battery bank energy × 1.3) ÷ Peak sun hours

Peak sun hours differ from daily sunlight hours. The factor of 1.3 accounts for inefficiencies.

Example:

(1,920 × 1.3) ÷ 5 = 499.2W

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### Formula for Number of Solar Panels:

Number of panels = Minimum solar array ÷ Panel rating

Example:

499.2 ÷ 250 = 1.9 (Rounded up: 2 panels of 250W).

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### Alternate Calculation (100% Depth of Discharge):

1. Depth of discharge: 100%.

2. Battery energy remains constant whether connected in series or parallel. For example, two 12V 100Ah batteries yield a total of 2,400Wh.

Formula for Usable Energy:

(100 ÷ 100) × (2 × 12V × 100Ah) = 2,400Wh

Solar Array Size:

Minimum solar array = (2,400 × 1.3) ÷ 5 = 624W

Number of Panels:

624 ÷ 350 = 1.78 (Rounded up: 2 panels of 350W)

Alternate option: 2 panels of 400W for a total of 800W.