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 daily use in kWh, the power per panel in Wp and the number of peak sun hours, and this calculator instantly works out how many panels and what system size you need. That gives you a realistic first estimate before requesting quotes.
結果
8
Number of solar panels
- System size
- 3.2 kWp
How this was calculated
- 1Daily output per panel400 Wp × 3.5 uur = 1,400 Wh
- 2Number of panels10,000 Wh ÷ 1,400 Wh = 7.14
公式
Number of panels = (daily use in Wh) ÷ (power per panel × 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/m²) 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.
ステップ解説
- 1Enter your average daily electricity use in kWh.
- 2Enter the power per panel (Wp) and the number of peak sun hours for your location.
- 3See the number of panels needed and the total system size in kWp instantly.
計算例
10 kWh per day, 400 Wp panels, 3.5 peak sun hours
→ About 8 solar panels needed (3.2 kWp system).
15 kWh per day, 350 Wp panels, 4 peak sun hours
→ 10.71 rounds up to 11 panels (3.85 kWp system).
6 kWh per day, 450 Wp panels, 3 peak sun hours
→ 4.44 rounds up to 5 panels (2.25 kWp system).
Reference table
| Daily use (kWh) | Panels (400 Wp, 3.5 h) | System size (kWp) |
|---|---|---|
| 5 | 4 | 1,6 |
| 8 | 6 | 2,4 |
| 10 | 8 | 3,2 |
| 12 | 9 | 3,6 |
| 15 | 11 | 4,4 |
| 20 | 15 | 6,0 |
Assumes 400 Wp panels and 3.5 peak sun hours per day; use the calculator above for your own values.
よくある間違い
- Confusing peak sun hours with the number of daylight hours, leading to a far too low panel count.
- Not accounting for system losses (cabling, inverter, temperature), which typically cost 10 to 15% of the yield in practice.
- Forgetting that you always round up: a result of 7.1 panels means you need to buy 8 whole panels.
Limitations
- This calculation does not account for roof orientation, shading or system losses; an installer will calculate this more precisely.
活用シーン
- Making an initial estimate before getting a quote from an installer.
- Sizing an off-grid or battery system based on your energy needs.
- Comparing different panels and wattages before choosing a supplier.
よくある質問
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.
What does Wp (watt-peak) mean?
Wp is the maximum power a panel delivers under standardised test conditions (full sun, 25°C). In practice, real-world output is often somewhat lower.
Does roof orientation and tilt make a difference?
Yes, a south-facing roof with a tilt of around 30 to 35 degrees gives the highest yield. East- or west-facing roofs typically produce 10 to 20% less; this calculator assumes an average, optimal situation.
How many solar panels does an average household need?
An average Dutch household uses about 2,900 kWh per year (around 8 kWh per day), which works out to roughly 6 to 8 panels of 400 Wp, depending on peak sun hours and available roof space.
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