Solar Battery Sizing Guides
Everything you need to size solar panels for battery charging. Pick your battery capacity below, or use the calculator to find the exact panel wattage for any combination of voltage, chemistry, and charge time.
Ah
hrs
Required solar panel size
0W
To charge a 100Ah 12V Lithium (LiFePO4) battery in 5 hours
Energy to charge
1.26kWh
If you use 100W panels
3
panels needed
If you use 200W panels
2
panels needed
171 kg
CO₂ avoided per year
0.04
equivalent US homes powered
8
trees planted equivalent
$74
estimated annual savings
| Chemistry | Efficiency | Cycle Life | Panel Watts |
|---|---|---|---|
| Lithium (LiFePO4) | 95% | 3,000–5,000 | 252 W |
| Deep Cycle AGM | 85% | 500–1,000 | 283 W |
| Lead-Acid Flooded | 80% | 300–500 | 300 W |
Tap to see sensitivity analysisSensitivity analysis
| Scenario | Value |
|---|---|
| Low (-20%) | 202 W |
| Expected | 252 W |
| High (+20%) | 302 W |
Battery chemistry has the biggest effect \u2014 switching from lead-acid to lithium reduces required panel watts by ~20%.