Solar Panel Calculator
To fully cover your daily electricity use with solar panels, you need enough panels to produce sufficient energy on an average day. Enter your usage, the power per panel and the number of peak sun hours.
Result
8
Number of solar panels
- System size
- 3.2 kWp
How this was calculated
- 1Daily output per panel400 Wp ร 3.5 uur = 1,400 Wh
- 2Number of panels10,000 Wh รท 1,400 Wh = 7.14
Formula
Number of panels = (daily use in Wh) รท (power per panel ร peak sun hours)
Peak sun hours are not the number of hours the sun shines, but the number of hours at full-intensity sunlight (1000 W/mยฒ) that would deliver the same total energy as a real day. In the Netherlands this averages around 3 to 3.5 hours per day over the year. You multiply the power per panel by the peak sun hours to get the daily output per panel, then divide your total daily use by that figure.
Worked examples
10 kWh per day, 400 Wp panels, 3.5 peak sun hours
โ About 8 solar panels needed (3.2 kWp system).
Common mistakes
- Confusing peak sun hours with the number of daylight hours, leading to a far too low panel count.
Limitations
- This calculation does not account for roof orientation, shading or system losses; an installer will calculate this more precisely.
When to use it
- Making an initial estimate before getting a quote from an installer.
Frequently asked questions
How many peak sun hours does the Netherlands average?
On average around 3 to 3.5 hours per day over the whole year, with significant seasonal variation.
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