Solar System Sizing Calculator
Calculate the solar panel system size you need based on your electricity usage and province. Includes ROI analysis, 10-year projections, and system type comparison.
Quick Calculator Get a fast estimate
kWh
%
System Size Required
2,1 kWp
Number of Panels
5 × 450W panels
Estimated Cost
R 33 939
Annual Saving
R 9 845
Payback Period
3,4 years
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How Solar Sizing Works
System size (kWp) = Daily kWh needed ÷ (Peak sun hours × 0.8). South Africa receives 4.8–6.2 peak sun hours daily depending on province. The 0.8 factor accounts for system losses (temperature, wiring, inverter efficiency). At R15–R18/Wp installed, a 3 kWp system costs R45,000–R54,000.
Need more detail?
Extended Calculator More options, charts, and scenario comparison
kWh
%
R/kWh
R/Wp
%/yr
Recommended System
2,1 kWp (5 panels)
Install Cost
R 33 939
Annual Saving
R 9 845
Payback
3,4 yrs
Peak Sun Hours by Province
| Province | Peak Sun Hours/Day |
|---|---|
| Northern Cape | 6.2 |
| Limpopo | 5.8 |
| North West | 5.7 |
| Free State | 5.6 |
| Gauteng | 5.5 |
| Mpumalanga | 5.3 |
| Western Cape | 5.0 |
| KwaZulu-Natal | 4.8 |
| Eastern Cape | 4.7 |
Need full precision?
Professional Calculator Complete parameters, sensitivity analysis, and detailed breakdown
Detailed Solar ROI Analysis
kWh
h/day
%
R/kWh
%
hours
System Type
System Cost Estimate
R 109 045
System size
2,1 kWp
Payback
11,1 yrs
15-yr NPV
R 69 522
Cost Breakdown
| Component | Cost |
|---|---|
| Solar Panels (5 × 450W) | R 11 000 |
| Inverter/Charger | R 3 182 |
| Battery Bank (4h backup) | R 80 640 |
| Installation & Labour | R 14 223 |
| Total | R 109 045 |
15-Year Cash Flow (with 12% tariff escalation)
| Year | Annual Saving | Cumulative | NPV |
|---|---|---|---|
| Year 1 | R 9 845 | R 9 845 | -R 99 929 |
| Year 3 | R 12 350 | R 33 222 | -R 80 672 |
| Year 5 | R 15 492 | R 62 545 | -R 59 961 |
| Year 7 | R 19 433 | R 99 329 | -R 37 689 |
| Year 10 | R 27 302 | R 172 772 | -R 1 090 |
| Year 15 | R 48 115 | R 367 029 | R 69 522 |
SA Tax Incentive: Individuals can claim a 25% rebate (up to R15,000) on solar panel installation costs under SARS Section 6C, for panels installed on 1 March 2023 – 29 February 2024. Businesses can also depreciate solar assets. Consult a tax practitioner.
Frequently Asked Questions
Feed-in tariffs are available in some municipalities (Cape Town's Small-Scale Embedded Generation programme, City of Johannesburg). Eskom direct customers have limited feed-in options. Check with your municipality for current rates and connection requirements.
Section 6C of the Income Tax Act allowed a 25% rebate on solar panel costs (up to R15,000 per individual) for panels installed between 1 March 2023 and 29 February 2024. This incentive may be extended — check SARS for current status. Businesses can depreciate solar assets.