Solar / Backup Power ROI Calculator — South Africa
Model your full solar return: Eskom savings + Section 12B 125% tax deduction + rental premium uplift. Find your real payback period as a property investor.
Solar / Backup Power ROI Calculator
Three income streams: electricity savings · tax deduction · rental premium
☀️ Typical SA Solar System Sizes & Costs (2026)
| System | PV Size | Battery | Approx Cost | Best For |
|---|---|---|---|---|
| Basic Backup | 2kW | 3–5kWh | R30,000–R45,000 | Lights, WiFi, phones |
| Mid-Range | 3kW | 5kWh | R45,000–R65,000 | 2–3 bed rental, best ROI |
| Full System | 5kW | 10kWh | R75,000–R100,000 | 4 bed home, aircon |
| Premium | 8kW+ | 15kWh+ | R110,000–R160,000 | Large home / pool pump |
Prices are indicative 2026 ranges including VAT, installation, and commissioning. Get at least three quotes from registered installers.
How to Use This Calculator
Use the quick-fill buttons at the top to populate a typical system size, then adjust to your specific installer quote. The Section 12B deduction applies the 125% first-year tax allowance — tick this if the property earns rental income and you are a taxable entity. Select your marginal tax rate for an accurate after-tax cost.
Enable the rental premium section to include the additional rental income the solar system generates. The year-by-year table shows how tariff increases compound the electricity saving over time, and highlights the year when the cumulative benefit recovers the full installation cost.
Does Solar Improve Your Cash-on-Cash Return?
Run the Cash-on-Cash Return Calculator with the rental premium included to see the full impact on your investment metrics.
Cash-on-Cash Return Calculator →Section 12B: The Most Powerful Solar Incentive Available to SA Property Investors
Section 12B of the Income Tax Act was significantly enhanced in the 2023 Budget and has been confirmed active for the 2026 tax year. It allows taxpayers who install qualifying renewable energy assets — including solar PV panels — to deduct 125% of the installation cost in the first year of use, provided the asset is used in the production of income.
For a property investor paying tax at the 41% marginal rate and installing a R80,000 solar system: the Section 12B deduction is R100,000 (125% × R80,000). The tax saving is R41,000 (R100,000 × 41%). The effective after-tax cost of the installation is R39,000 — less than half the invoice price. This changes the economics of solar dramatically and makes it one of the most tax-efficient investments available to SA property investors in 2026.
Important: the deduction requires that the solar asset is used in the production of rental income. Consult a registered tax practitioner to confirm eligibility, structure the claim correctly, and ensure compliance with SARS requirements before submitting.
Three Income Streams from a Single Solar Investment
What makes solar uniquely attractive for SA rental property investors is that it generates three separate financial benefits simultaneously — a combination not available from any other property improvement.
1. Electricity cost savings. Eskom's retail tariff has increased at an average of 12–15% per year over the past decade. A 3kW system generating 330kWh/month at R2.90/kWh saves approximately R11,500 per year in year one — and that saving grows every year as tariffs rise. Over 10 years with 10% annual tariff increases, the cumulative electricity saving on a 3kW system exceeds R180,000.
2. Section 12B tax deduction. As detailed above, the 125% first-year deduction can halve the effective cost of the installation for taxpayers at higher marginal rates.
3. Rental premium uplift. SA rental market data consistently shows solar-equipped properties command premiums of 5–15% above comparable non-solar properties. For a R12,000/month property, even a conservative 7% premium adds R840/month or R10,080/year in additional rental income — enough on its own to recover the cost of a basic backup system within 4–5 years.
Choosing the Right System Size for a SA Rental Property
The optimal system size for a rental property is different from a primary residence — the goal is maximising ROI, not maximising comfort. For a 2–3 bedroom rental, a 3kW PV system with a 5kWh battery is widely regarded as the sweet spot: it covers all essential loads during load shedding (lights, WiFi, TV, refrigerator, device charging) and the cost-per-kW is lower than smaller systems.
A 3kW system also hits a pricing band where the Section 12B deduction makes the after-tax cost very competitive — typically R25,000–R35,000 at a 41% marginal rate. At that after-tax cost, the combination of electricity savings and rental premium can achieve payback in under 3 years.
For properties in higher rental brackets (R20,000+/month), a 5kW full system makes sense — the larger rental premium on a higher-value property, combined with greater electricity savings, justifies the larger capital outlay, and the Section 12B deduction scales proportionally with the installation cost.
Frequently Asked Questions
Solar ROI and Section 12B — common questions