Solar - when does it pay for itself?

Your system's cost against the electricity it saves, year by year, until it has paid for itself.

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Example data - to be completed. These numbers belong to a sample household. Move the sliders to your own quote →

Breaks even in year 5

A R 120 000 system saves about R 25 200 in year 1 and is R 3 668 139 ahead after 25 years.

Breaks even
year 5
The year the savings have covered the cost
Payback
4.9 years
Counting part of the last year
Net gain at 25 years
R 3 668 139
Savings and interest earned, less the cost, battery and interest
Saved in year 1
R 25 200
Electricity you no longer buy, less cloudy-day Eskom top-up
Interest forgone
R 28 764
What the cash would have earned at 7.25% while the system paid itself back
Days without power
none - Eskom backs up
Hybrid: Eskom covers cloudy days

What this means

  • The savings cover the R 120 000 system in about 4.9 years.
  • Year 1 saves about R 25 200 (R 2 100 a month); price increases make every later year worth more.
  • After 25 years you are R 3 668 139 ahead, in rand as spent.
  • Paying cash gives up about R 28 764 of interest at 7.25% until the savings have paid the system back. Once ahead, the savings earn 7.25%: R 1 534 610 over 25 years.
  • Figures are calculations, not advice - no product or installer is recommended.

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Assumptions

  • System cost R 120 000, paid in cash - the 7.25% a year the money could have earned is counted until the system has paid itself back. Once ahead, the savings earn 7.25% a year.
  • 600 kWh a month of grid electricity replaced, at R 3.50 a kWh in year 1, rising 10% a year.
  • Nothing bought from Eskom on cloudy days.
  • Panels produce 0.5% less each year.
  • No battery replacement counted.
  • Rand as spent (not adjusted for inflation); maintenance, insurance and the value of backup power are left out.

Where the typical figures come from

  • Price increases (Low 6%, Moderate 9%, High 13%): NERSA's Eskom decisions - 12.74% for 2025/26, then 8.76% (Eskom) and 9.01% (municipal) for 2026/27 after the R54.7bn correction; Low is the original 2026-28 path (5.36% / 6.19%). Engineering News, 2026, Eskom, 2026.
  • System and battery prices: published South African installer price guides - OurPower, 2026, EnergyBee, 2026, EnergyBee batteries, 2026.
  • Off-grid days without power - solar output by region: EU JRC PVGIS 5.2 (satellite data 2005-2020), panels at 30 degrees facing north, 14% losses - Johannesburg 4.8, Cape Town 4.6, Durban 4.1, Bloemfontein 5.0, Gqeberha 4.4 kWh a day per kWp over the year. PVGIS, European Commission.
  • Off-grid - rainy days a month: days with 1 mm of rain or more, 1991-2020 normals (South African Weather Service / NOAA), from each city's climate table - Johannesburg 67 a year, Cape Town 65 (counts 0.1 mm, so a little pessimistic), Durban 86, Bloemfontein 54, Gqeberha 71. Johannesburg, Cape Town, Durban, Bloemfontein, Gqeberha.
  • Off-grid - a rainy day makes 25% of a clear day: the top of the 10-25% usually quoted for heavy overcast; a general figure, not measured in South Africa. Solar Calculator.
  • Interest you could have earned - 7.25%: the SARB repo rate after the 25-basis-point hike of 23 September 2026. Money-market funds pay close to it (Old Mutual Money Market Fund 6.61% a year in April 2026, before the hike); a 12-month fixed deposit pays a little more (GoTyme 8.75%, July 2026). Paying cash, the shortfall grows at this rate (interest forgone); once ahead, the savings earn it. Trading Economics, Sep 2026, Old Mutual, GoTyme.
  • Loan interest - 10.75%: prime (repo 7.25% + 3.5) from 24 September 2026; your bank's offer may be higher. Briefly News, Sep 2026.
  • Estimates, not sourced: household usage per size, the cloudy-day Eskom top-up (about 15% of use), the extra-large system's price and the labour in a battery swap. Off-grid: rain comes in spells of up to 3 days, half of each day's use is after dark, and the battery figure is usable storage. Use your own bill and quote.

What happens to your statement

A statement we can read is never written to disk and is never kept. Your PDF or CSV is read in memory, the transactions are taken out of it, and the file itself is gone before the page comes back. We never have a copy of a statement we could read.

The one exception is a statement laid out in a way we cannot read yet. Then we keep one encrypted copy of that file, not linked to your account here, so we can teach the site to read that layout, and we delete it after 30 days. Nothing from it is added to your transactions.

The transactions we read out of it are kept for 13 months, so that your statements are still here when you come back next month and so this September can be put beside last September. What is kept for each transaction is exactly this: the date, the description as your bank printed it, the shop name we worked out from it, the amount, the running balance if your bank printed one, and the category it ended up in. Alongside them we keep which bank it was, which account type your bank printed on it, and which dates it covered.

We keep your account number, and we hold it encrypted. It is on the screen because it is the only thing that tells two accounts at the same bank apart — two Investec accounts can both be called "Private Bank Account". It is stored scrambled with a key that is not kept in the same place as the number, and it is deleted when the rest of your statements are: with your account if you have one, or with the 13 months if you do not.

We put a cookie in this browser so that your statements are still here when you come back. It holds one random number and nothing else. That cookie is the only thing that joins one visit to the next, it is the only way we can find your statements again, and clearing your browser's cookies ends it — after that we have no way to match you to anything we hold, and it is deleted when it expires.

We do not ask who you are. We do not store your name, and we do not store your IP address, and you can use all of this without telling us anything about yourself. The account number above is the one thing we read off the statement that identifies the account, and we never ask you to type it in.

If you create an account, we store your email address and a scrambled form of your password — nothing else about you. That is the only thing an account changes: your statements follow your email address instead of this browser, so you can reach them from your phone or from another computer. We never keep the password itself and it cannot be worked back out of what we store.

After 13 months it is deleted automatically, by a job that runs every night, and the 13 months starts again each time you come back. An account is the exception: your statements are kept for as long as the account exists — a tool for putting this September beside last September cannot delete the September you came back to compare against.

We also keep a count of how often a shop lands in a category — like “CHECKERS, Groceries, 412 times” — and your corrections improve it. That count is all we keep: no amounts, no dates, and no link to you or to anyone else.

Nothing about your statement leaves our servers. It is not sent to any other company, it is not used to advertise to you, and it is not sold.

When you tell us to always file a shop or a description under a category, that rule is kept with your statements — the text it matches, the category you chose and, if you limited it to one account, which account; nothing else. The Rules page lists every rule and deletes any of it.

The full privacy policy and the terms of use say the same things at greater length.

You need to accept this before you upload a statement. It stays in the left-hand menu, so you can read it again at any time.