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Solar savings calculator
Put in your monthly bill and see a suggested system size, the monthly saving and a payback range. It takes about a minute and needs no email address.
Your bill in, a system size out
Move the sliders. It takes your bill, sizes the array to your daylight use, and shows the saving in today's rand. No email needed.
- Suggested array
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- Solar used per month
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- Typical installed cost
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- Simple payback
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Indicative only. Uses about 1 700 kWh per kWp a year for Ermelo (PVGIS 5.3, north-facing, 26° tilt) and typical South African installed costs of R12 000 to R18 000 per kWp. Home estimates assume a battery. The payback after Section 12B assumes the 27% company tax rate.
How the numbers are worked out
- Consumption. Your bill divided by the cost per kWh. For businesses we count 80% of the bill as energy, because fixed and demand charges do not shrink with solar. For homes, 92%.
- System size. Businesses and farms are sized to the share used in daylight. Homes are sized to the whole month, with a battery to carry the evening.
- Generation. About 1 700 kWh per kWp a year in Ermelo (PVGIS 5.3, north-facing, 26° tilt, 14% losses). On the highveld the winter months are among the strongest.
- Saving. Not every unit generated replaces a unit bought, because a solar curve never matches a load curve exactly. Businesses: 60% plus 35% of the daytime share. Homes with a battery: 75%.
- Cost and payback. Typical South African installed cost of R12 000 to R18 000 per kWp for commercial systems, shown in today's rand without inflation or discounting.
How accurate is the calculator?
It is a first estimate from three numbers. Real proposals use twelve months of accounts, your tariff structure, the roof or ground available and a site visit, and can land higher or lower.
Why does the daytime share matter so much?
A solar array only produces in daylight. Power used at night has to come from the grid or a battery, so a business that runs 07:00 to 17:00 saves far more per kWp than one that runs at night.
Why are home estimates different?
Homes use most of their power in the morning and evening, so a home system normally includes a battery. The home estimate assumes one and sizes the array to the whole monthly consumption.
What is Section 12B?
A tax allowance that lets a business deduct 100% of the cost of a solar system under 1 MW in the first year. At the 27% company rate that takes roughly a quarter off the effective cost. Confirm the treatment with your accountant.
Turn the estimate into a real quote
It opens as a WhatsApp message to Mari Louise with a reference number, so the first call is about your site instead of the basics.
Rather talk? Call the office on 017 004 0001 or WhatsApp 072 326 0268.
Send the bill, get the real number
The calculator gives a range. One electricity account and a site visit give a price.