kWh to panel count
How many solar panels do you need for kWh per day?
Daily energy does not convert to a fixed panel count. The answer depends on peak sun hours, system losses, the share of consumption you want to cover, and each panel's rating.
Convert the bill to daily energy
If you have a monthly total, divide it by 30 for a planning-day average. Use seasonal or measured data when the load changes sharply across the year.
Convert kWh per day to array watts
array W = daily kWh × 1,000 × coverage ÷ (peak sun hours × efficiency)For 10kWh per day, five peak sun hours, 80% efficiency, and full coverage, the theoretical array is 2,500W.
Round to whole panels
With 400W panels, 2,500 ÷ 400 gives 6.25 panels. Round upward to seven panels, producing a 2.8kW installed array. Recalculate output from 2.8kW, not from the smaller theoretical array.
| Daily energy | Sun hours | Efficiency | Theoretical array |
|---|---|---|---|
| 5kWh | 5 | 80% | 1.25kW |
| 10kWh | 5 | 80% | 2.5kW |
| 20kWh | 5 | 80% | 5kW |
Peak sun hours are not daylight hours
Use a solar-resource source for the location and season being planned. Shade, orientation, temperature, clipping, snow, and downtime still need separate checks.
Enter your own values in the solar panel calculator. If you already know the installed array, use the panel output calculator.
Whole-panel examples
With 5 peak sun hours, 80% efficiency, full coverage, and 400W panels, plan on 4 panels for 5kWh/day, 7 panels for 10kWh/day, or 13 panels for 20kWh/day. These are planning examples; change the assumptions for your site and recalculate after rounding.