Panel count tool
How Many Solar Panels Do I Need?
Estimate panel count, system size and roof area from monthly electricity use. Default example uses 600 kWh/month.
Default example (600 kWh/month): about 8 panels at 450 W (≈ 3.5 kW), needing roughly 16.8 m², generating around 5 775 kWh/year.
Panels
8
System size
3.5 kW
Roof area
≈ 16.8 m²
Annual generation
5 775 kWh
Formula in plain language
- Take annual kWh ≈ monthly × 12.
- Multiply by your target offset (we use 80%).
- Divide by specific yield (kWh produced per kW installed per year).
- Convert kW to panels using module wattage.
Target offset of 80% of annual consumption.
Specific yield 1650 kWh per kWp per year (indicative SA rooftop).
450 W panel modules; roof area ≈ 2.1 m² per panel including spacing.
Real roofs vary with shading, orientation, pitch and inverter clipping.
Static examples
| Monthly use | System | Panels | Roof area |
|---|---|---|---|
| 350 kWh | 2.0 kW | 5 | ≈ 10.5 m² |
| 600 kWh | 3.5 kW | 8 | ≈ 16.8 m² |
| 900 kWh | 5.2 kW | 12 | ≈ 25.2 m² |
Frequently asked questions
How do you estimate how many solar panels I need?
We convert monthly kWh into an annual target (default 80% offset), divide by a typical South African specific yield (kWh per kWp), then divide capacity by panel wattage.
Will this match my roof?
Not exactly. Orientation, shading, pitch and usable area change real panel counts. Use the personalised roof ROI report for satellite-based geometry.
Related guides
Next step
Get a personalised estimate for your roof using satellite data, your usage and local tariff where available.