Calculator
Solar Panel Quantity Calculator
For consumers, students & professionals. Result, assumptions, chart, comparisons and recommendations.
Unit system— all inputs and outputs convert automatically
Inputs
Enter your data — results update live.
Recommended system size
8.2
kW-DC
Breakdown chart
Visual comparison of each component (× 400W).
- Panels needed
- 21.00 × 400W
- Roof area (@ 6 m²/kW)
- 49.30 m²
- Est. annual output
- 10800.00 kWh
Methodology & sources
Formula
kW = (kWh/day × offset%) / (sun × derate); Panels = ceil(kW·1000 / W)Sources
- • NREL PVWatts
- • IEC 61215