Solar Savings & Payback Calculator (South Africa)
Work out the realistic payback on home solar in South Africa, not the rosy number. Free calculator that shows what actually eats your savings.
Most solar calculators quote a payback that never matches reality, because they pretend you use every kilowatt your panels make, that prices stand still, that your battery lasts forever, and that you paid cash with money that could not have earned a cent anywhere else. This one is honest. Put in your real numbers and it shows the figure a salesman quotes next to the figure you are actually likely to get, and exactly what eats the difference.
Everything you paid, including panels, inverter, battery, and installation.
The combined rated size of your panels, on the quote in kilowatt peak.
Set 0 if you have no battery. With no battery, daytime surplus is wasted unless your municipality pays for it.
Roughly 5 over most of South Africa. A bit higher in the Northern Cape and Highveld, a bit lower on the KZN coast.
Financing spreads the cost but adds interest, which pushes the real break even out. Cash ties up money that could have earned interest, covered lower down under the honest bits.
Cash you put down on day one. The rest is the amount financed.
A personal or solar loan often sits around prime plus a few percent. An access bond is cheaper, near the bond rate.
How long you repay over. A longer term means smaller monthly payments but more interest paid in total.
Rands per kWh. Use the energy charge per unit off your bill, not your whole bill divided by units, or the saving comes out too high. The presets are rough starting points, so set your own for a real answer.
That looks high for an energy charge. Check you have not divided your total bill by units, because the fixed and service charges in there inflate the saving.
Your average daily usage. A typical home runs 15 to 30 kWh a day. Check a month on your bill and divide by 30.
How much of your power you use while the sun is up. Geyser, pool pump, and work-from-home push this up, an empty house pushes it down.
SA tariffs have climbed fast for years. This makes future savings worth more, so it is the one factor that helps your case.
Tick this only if you have cut the supply entirely. Off grid you stop paying the monthly fixed and service charge as well as the units, so that saving counts too. There is no export to the grid and no extra solar fixed charge, so those drop away.
The standing, service, or capacity charge that used to land on your bill every month before you cut the connection. This rises over time the same as the tariff.
Panels slowly make less power as they age, around half a percent a year. Small, but it adds up over 20 years.
A lithium battery does not last forever, so budget for one replacement during the life of the system. This figure follows your battery size until you change it. Battery prices have fallen for years, so a swap a decade from now may well cost less, adjust it to your own view.
Most home lithium batteries last around 10 to 15 years depending on how hard they cycle.
The honest cost of tying up your cash. If you had left it in a money market or income fund instead it would have grown, so a rand saved years from now is worth less than a rand in hand today. Set to 0 to ignore this.
What your municipality pays you for power you push back to the grid. Leave at 0 unless you are registered for feed-in, because most pay nothing without it.
Some municipalities move solar homes onto a higher monthly fixed charge. The salesman never mentions this one, so add it if it applies to you.
What eats your returns over 20 years
Money in your pocket over time
These are estimates to help you sanity check a quote, not financial advice or a guaranteed return. Real results depend on your roof, your habits, your tariff, and the weather. Always get the actual figures off your own bill and quote before deciding.
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How solar payback really works in South Africa
Solar is one of the better investments a South African household can make, but only if you go in with honest numbers. The figure that decides everything is how much of your own generation you actually use, not how big your system is. Power your panels make while nobody is home, and that your battery cannot store, is simply wasted unless your municipality pays you to export it. That single fact is why a quote that assumes you use one hundred percent of your generation is a fairy tale, and why two homes with the same system can get very different paybacks.
Three things work in your favour. Your usage during daylight, which you can shift by running the geyser, pool pump and washing in the day. A battery, which lets you carry daytime surplus through to the evening. And the steady rise in the price of electricity, which makes every unit you generate yourself worth more each year. Three things work against you, the power you waste, the slow ageing of the panels, and the cost of replacing the battery once during the life of the system. A few municipalities also add a higher fixed charge once you register as a solar home, which quietly chips away at the saving.
The calculator above takes all of that and gives you two payback figures, the optimistic one a salesman tends to quote and the realistic one you are actually likely to see, then lists exactly what eats the gap between them. Set your own tariff off your bill, be honest about how much power you use in daylight, and leave the export credit at zero unless you are registered to be paid for it. The aim is not to talk you out of solar, it is to help you size it right and judge a quote with clear eyes.
While you are here, you can also compare your bank fees, check medical aid plans, or browse all our free South African tools and calculators.
Frequently asked questions
How long does solar take to pay for itself in South Africa?
For a well sized home system that you actually use during the day, a realistic payback is usually around six to ten years, after which the power is close to free until equipment needs replacing. The honest answer depends on four things, how much of your own generation you use rather than waste, your electricity tariff, how fast that tariff rises, and whether you bought a battery. Oversize the system or sit with an empty house all day and the payback stretches out, because the extra power your panels make simply goes to waste.
Why is my real solar payback longer than the salesman said?
Because the rosy quote usually assumes you use every single kilowatt your panels make, that the price of electricity never changes, and that your battery lasts forever. In reality a chunk of your daytime generation is wasted unless you can store it or sell it, panels slowly lose output as they age, a lithium battery needs replacing once during the life of the system, and some municipalities add a higher fixed charge once you go solar. This calculator puts the salesman's number next to the realistic one so you can see exactly what eats the difference.
Do I need a battery to save money with solar?
Not always, but it changes the maths a lot. Without a battery you only save on the power you use while the sun is shining, and any surplus is wasted unless your municipality pays you to export it. That suits a home that runs the geyser, pool pump and appliances during the day. A battery lets you store daytime surplus and use it at night, which lifts how much of your own power you actually use, but it adds a big upfront cost and a replacement bill down the line, so it has to earn its keep.
Will my municipality pay me for the extra solar power I send to the grid?
Usually very little, and often nothing at all unless you are registered. To be paid for export in South Africa you normally need to register as a small scale embedded generator with your municipality and have an approved bidirectional meter, and even then the rate paid for what you feed back is well below what you pay to buy power. Some metros, like Cape Town, run a feed in scheme, many do not. Unless you are signed up, treat exported power as wasted, which is why this tool sets the export credit to zero by default.
Does load shedding change the payback?
Load shedding is mostly about backup value rather than bill savings, so it sits a little apart from the payback sum. A solar and battery setup keeps your lights, fridge and wifi on when the grid is down, which has real worth to most households even when the schedule is quiet. The pure rand payback in this calculator is driven by the power you save buying every day, and you can treat the resilience during outages as a bonus on top of that.
How much do solar panels degrade over time?
Modern panels lose output slowly, on the order of half a percent a year, so after twenty years a panel still makes roughly ninety percent of what it did when new. It is small year to year but it quietly trims your savings over the life of the system, which is why an honest payback figure should include it rather than pretend the panels stay brand new forever.
This calculator gives estimates to help you sanity check a quote, it is general information and not financial advice. Real results depend on your roof, your habits, your tariff and the weather. Always work off the actual figures on your own bill and quote before deciding. Last reviewed June 2026.