How Many Solar Panels Do I Need in South Africa?

With Eskom tariffs rising every year and load shedding still a reality for millions of South Africans, home solar has gone from a luxury to a serious financial decision. But the question everyone asks first — "how many panels do I need?" — gets wildly different answers depending on who you ask.

Here is a straightforward, independent answer based on real system data from a 10kW installation in Pretoria.

Step 1 — Work Out Your Daily Energy Use

The starting point is your monthly electricity bill. Divide it by your tariff rate, then divide by 30 to get your daily kilowatt-hour (kWh) consumption.

For example: if you're on Tshwane at R3.49/kWh and your bill is R1,800/month:

• R1,800 ÷ R3.49 = 516 kWh per month
• 516 ÷ 30 = 17.2 kWh per day

That's your target — your solar system needs to produce at least 17.2 kWh on an average day to fully offset your usage.

Step 2 — Peak Sun Hours in Your Province

South Africa is one of the best countries in the world for solar, but production varies significantly by province and season.

Winter production in the Western Cape and KZN drops significantly due to cloud cover and shorter days. If your roof faces north (which it should for best results in the Southern Hemisphere), these numbers apply directly. East or west-facing panels produce about 15% less.

Step 3 — The Panel Count Formula

Once you have your daily kWh target and your peak sun hours, the calculation is straightforward. You also need to account for real-world losses — heat, wiring, inverter efficiency, and dust — which typically reduce output by about 15%.

System size (kW) = Daily kWh ÷ (Peak sun hours × 0.85)

Using our Gauteng example: 17.2 kWh ÷ (5.4 × 0.85) = 3.75 kW system

At 550W per panel: 3,750W ÷ 550W = 7 panels minimum, or 8–9 with a sensible buffer.

Real-World Example — 10kW System in Pretoria

For reference, a 10kW SolaX X1-Hybrid system in Gauteng with north-facing panels produces:

• Summer: 45–52 kWh/day on good days
• Winter: 28–35 kWh/day
• Annual average: approximately 38–42 kWh/day

That's enough to fully power a large home and charge a 10.2 kWh battery daily through summer. In winter, grid top-up of 5–10 kWh/day is typical for a house of that size.

Common System Sizes and What They Cover

These are rough 2026 market estimates for supply and installation. Add R30,000–R50,000 for a 10 kWh LiFePO4 battery if you want load shedding backup.

Don't Forget the SARS Tax Rebate

South African individual taxpayers can claim a 25% rebate on the cost of new solar panels, capped at R15,000, under SARS Section 6C. This applies to the panel cost only (not inverter or battery). Confirm with your tax practitioner whether you qualify for the current tax year.

Key Mistakes to Avoid

• Undersizing to save money upfront: A system that only covers 60% of your usage still leaves you with a meaningful bill. Size for 100% offset — you'll never regret extra panels, but you will regret too few.
• Ignoring the geyser: An electric geyser (3,000W) is the biggest single load in most homes. A 5kW inverter can't run a geyser and an air conditioner simultaneously. Either account for it in your system size or switch to a solar geyser or heat pump.
• Not accounting for winter: Always size for your winter production, not your summer production. A system that fully offsets in summer may only cover 60–70% in winter.
• Trusting one installer's quote: Get at least three quotes. Panel and inverter costs vary significantly between installers, and the upsell pressure in this industry is real.