Electricity prices and the numbers behind the calculator
NERSA approved a +12.74% increase for Eskom direct customers for 2025/26, effective 1 April 2025, and +11.32% for municipal bulk purchases from 1 July 2025. Residential customers then pay municipal rates that differ by city and by tariff block. Sources checked 2026-10-26.
There is no single South African home tariff. Cape Town, Johannesburg, eThekwini, Tshwane and Eskom direct supply all bill differently, and fixed charges sit on top of the per-unit rate. The model uses a range, R2.80 to R3.90 per kWh, and the calculator follows the rate you type in. Payback quoted to the month from one national rate is guesswork dressed up as precision.
Installed price ranges in the model
Summary of public installer quotes and published kit pricing, checked 2026-10-26. Estimates only.
Scale R0 to R240,000, battery excluded. Battery adds: 5 kWh +R40,000 to R55,000; 10 kWh +R60,000 to R80,000.
| System | Installed, no battery | Typical lease |
|---|---|---|
| 3 kW | R55,000 to R85,000 | R1,400 to R1,750 a month |
| 5 kW | R90,000 to R140,000 | R1,750 to R2,200 a month |
| 8 kW | R130,000 to R195,000 | R2,200 to R2,650 a month |
| 10 kW | R160,000 to R240,000 | R2,500 to R2,900 a month |
Generation assumptions
| Input | Default | Why |
|---|---|---|
| Peak sun hours | 5.0 a day | South African planning range is about 4.5 to 5.5. Coastal winter lower, Northern Cape higher. |
| System losses | 14% | Inverter, heat, dust and cabling. Applied before self-use. |
| Self-use, no battery | 65% of generation | Daytime loads only. The rest is exported or curtailed. |
| Self-use, with battery | 85% of generation | Stored solar covers part of the evening peak. |
| Tariff rise | 8% a year, editable | Below the 2025/26 approved increase, above long-run inflation. A planning choice, not a forecast. |
| Orientation factor | North 1.00, flat 0.92, east-west 0.88, south 0.75 | Coarse roof adjustment for the Southern Hemisphere. |
Sources and dates
- NERSA and Eskom retail tariff decisions for 2025/26: 12.74% for Eskom direct customers, 11.32% for municipal bulk supply. Checked 2026-10-26.
- Installed prices: public installer quote summaries and published residential kit pricing in South Africa, cross-checked 2026-10-26. Quotes vary by roof, cable run and brand, so they stay ranges.
- Lease ranges: published South African solar subscription and rent-to-own offers, cross-checked 2026-10-26.
- Sun hours: standard South African planning range of about 4.5 to 5.5 peak hours a day, stated as an assumption on every result.
If your bill shows a very different per-unit rate, type it into the calculator. The model follows your number, not the range on this page.