Roof area is the real system size limit
Budget and electricity bill determine what you want to install. Roof area determines what you can install. Before you pay for any sizing advice, spend 5 minutes with a measuring tape — it will save you from quoting surprises later. As a sanity check: a 3 kW system needs roughly a 14×15 ft clear area; a 5 kW needs 20×18 ft; 10 kW needs 30×24 ft (or multiple roofs).
Quick reference — roof size to kW
| Roof (sq ft) | Usable (70%) | 540W panels | Approx kW |
|---|---|---|---|
| 300 | 210 | 6 | 3.2 |
| 500 | 350 | 10 | 5.4 |
| 800 | 560 | 16 | 8.6 |
| 1200 | 840 | 24 | 13 |
| 2000 | 1400 | 40 | 21.6 |
Once roof area sets your maximum kW, refine the layout with our Tilt Angle Calculator, verify orientation with the Azimuth Calculator, and convert area into actual yield using local peak sun hours.