How the calculation works
- Real panel output = panel watts × 0.75, capped at your power station's maximum solar input.
- Charge time = battery Wh ÷ real panel output (in hours of strong sun).
- Days to charge = charge time ÷ your area's peak sun hours.
- Solar needed for your daily use = daily Wh ÷ (peak sun hours × 0.75).
Rules of thumb
| Battery | 100 W panel | 200 W panel | 400 W of panels |
|---|---|---|---|
| 300 Wh | ~4 sun hours | ~2 sun hours | ~1 sun hour |
| 1,000 Wh | ~13 sun hours | ~6.7 sun hours | ~3.3 sun hours |
| 2,000 Wh | ~27 sun hours | ~13 sun hours | ~6.7 sun hours |
| 3,600 Wh | ~48 sun hours | ~24 sun hours | ~12 sun hours |
Assumes 75% real-world efficiency and that the power station accepts the full panel wattage.
Getting the most from portable solar
- Point the panels at the sun and re-aim them every couple of hours. Panels lying flat lose a lot of output, especially in winter.
- Keep them out of the shade completely. A shadow across a single cell can cut a panel's output badly.
- Let them breathe. Output drops as panels heat up, so leave an air gap underneath.
- Wire them in series, within the input's voltage limit, for better charging in low light, or in parallel when series would go over that limit.
Not sure how much energy you use per day? Add your appliances to the power station size calculator first.