How Many Solar Panels Do I Need? Sizing a System for Your SA Home

One of the first questions every homeowner asks is how many solar panels they need. The honest answer is that it depends on how much electricity you use, how much roof space you have, and what you want the system to do. Here is a simple way to work it out.

Start with your electricity usage

Look at your municipal or Eskom bill and find your monthly consumption in kilowatt-hours (kWh). The average South African household uses somewhere between 600 and 1,200 kWh per month. Divide your monthly figure by 30 to get your daily usage.

Factor in South Africa's excellent sunshine

South Africa is one of the sunniest countries in the world, averaging between 5 and 7 peak sun hours per day depending on the province. The Northern Cape and Free State sit at the higher end, while the coastal regions are slightly lower. More sun hours means each panel produces more energy, so fewer panels are needed for the same output.

A quick sizing estimate

A modern solar panel is typically rated around 450 to 550 watts. As a rough guide:

• A small home using about 15 kWh a day needs roughly 3 to 4 kW of panels, or about 8 to 10 panels.
• A medium home using about 25 kWh a day needs roughly 5 to 6 kW, or about 12 to 14 panels.
• A large home using 40 kWh or more a day needs 8 kW or more, or 18-plus panels.

These are starting points. The simplest way to get a tailored number is our system size calculator, which factors in your usage and location.

Roof space and orientation

Each panel takes up roughly 2 square metres. North-facing roofs are ideal in the Southern Hemisphere, but east and west facing sections still work well and can actually spread production across the morning and afternoon. Shading from trees, chimneys or neighbouring buildings reduces output, so a good installer will assess this during a site visit.

Do not forget the battery and inverter

Panels only generate during daylight. If you want power at night or during load shedding, the size of your battery and inverter matters just as much as panel count. A bigger panel array charges your battery faster but does not extend backup time on its own.

Get an accurate assessment

A sizing estimate gets you in the ballpark, but the final number should come from a proper assessment of your roof, usage pattern and goals. Request free quotes from verified installers who will design a system that fits your home.