Calculate my roof ROI

Sizing tool

Solar System Size Calculator

Get an indicative system size from monthly kWh or bill amount. For roof-accurate ROI, use the personalised report.

Result: about 3.5 kW (8 × 450 W panels), year-1 savings roughly R15 233–R20 610, installed R58 520–R74 480 grid-tied.

System size
3.5 kW
Panels
8
Installed range
R58 520–R74 480
Simple payback
3.7 yrs
Fallback residential rate used for bill→kWh: R4.1379/kWh (variable energy only)
Analyse my roof and bill — R149

Frequently asked questions

Is this the same as the personalised roof report?

No. This tool uses national yield and tariff assumptions. The R149 report uses your roof geometry from satellite data and your actual tariff where available.

3.5 kW guide Nearest size page Battery calculator Backup sizing

Next step

Get a personalised estimate for your roof using satellite data, your usage and local tariff where available.

Calculate my roof ROI Already have solar? Add your system to the research map