The return of a solar system mostly arises as saved electricity costs – not as a payout. How high it turns out depends on the investment, self-consumption, electricity price and feed-in tariff, and can only be honestly calculated with your own figures. A blanket percentage with no regard for roof and consumption is number-dressing. (As of: July 2026)
Key points in brief
- The biggest income item is invisible: every kilowatt-hour you consume yourself replaces more expensive grid electricity – it doesn't appear on any account, but it lowers the electricity bill.
- The return isn't a fixed property of the system, but the result of the investment, the consumption profile and your utility's tariffs.
- Anyone who guarantees you an exact return figure in a sales conversation has made up at least one of the input figures.
- The calculation method is simple – only the honest assumptions behind it are demanding.
- This guide provides context and doesn't replace financial or investment advice.
What does «return» even mean for a solar system?
Here, return means: the system's annual benefit, measured against the net investment. The benefit consists of the same three cash flows that decide the whole profitability: saved electricity costs through self-consumption, the remuneration for the fed-in surplus, and – once – the one-off feed-in incentive plus the tax deduction, which lower the investment.
The difference from a classic financial investment lies in the first item. An account pays out interest; the solar system «pays» mainly by making your electricity bill smaller. That feels less like a return, but works just the same – and is, moreover, independent of what the grid operator pays for the surplus. That's exactly why the most common counter-argument falls short too: a low feed-in tariff only weighs down the smaller of the two ongoing incomes.
Why are blanket return promises disreputable?
Because each of the input figures turns out differently from case to case – and nobody knows some of them for 25 years. The grid purchase price differs considerably by municipality and typically sits somewhere between around 25 and 35 Rp./kWh; feed-in brings, depending on the utility, between the statutory floor of 6 and about 14 Rp./kWh (the comparison). On top of that come your consumption profile, the roof situation and the question of how tariffs develop over the years.
A reputable statement therefore works with ranges and discloses the assumptions. Anyone who writes «a guaranteed 8 percent» into the quote instead has either pinned down the electricity price for a quarter century or guessed your consumption profile – both belong among the warning signs in a sales conversation.
How do you calculate the return realistically?
The calculation method itself fits on a beer mat. What's demanding is only putting in honest figures:
| Step | What you plug in | Where the figures come from |
|---|---|---|
| 1. Net investment | Quote total minus one-off feed-in incentive minus tax saving | Cost guideline values, quote, tax return |
| 2. Saved electricity costs | self-consumed kWh × your grid purchase tariff | Electricity bill, consumption profile |
| 3. Feed-in revenue | fed-in kWh × your utility's feed-in tariff | Tariff overview |
| 4. Deduct operating costs | Meter rental, reserve for the inverter | Maintenance costs |
| 5. Return | (2 + 3 − 4) ÷ 1 | – |
Calculation scheme, as of: July 2026. The split between step 2 and 3 is determined by your self-consumption rate – it's the most sensitive variable in the whole calculation.
Two points decide the quality of the result. First, the self-consumption rate: self-consumed electricity is worth roughly two to four times as much as fed-in electricity – an overly optimistic rate dresses up the calculation more than any other mistake. Second, the tariff assumptions: calculate with today's tariffs and treat future price increases as a reserve, not as a basis.
Return, payback, levelised cost – what does each figure tell you?
Three terms, three perspectives on the same system. The payback period says when the investment is earned back – typically in a range of around ten to fifteen years depending on the constellation; the influencing factors are described there. The return translates the annual benefit into a rate of interest on the investment. The levelised cost, finally, asks what the self-produced kilowatt-hour costs over the lifetime – the derivation is often the most revealing of the three perspectives, because it doesn't need tariff forecasts.
For a consultation, the rule of thumb is enough: payback for the gut feeling, levelised cost for the comparison with grid electricity, return for the comparison with other uses of the money.
Which levers actually improve the return?
You can change little about your utility's tariffs – but you can about three other variables. The most effective lever is self-consumption: shifting consumption into the sunlight hours, integrating a heat pump and electric car. The second is sizing: a system that fits the roof and the (future) consumption beats any extreme variant – sparingly covering the roof is rarely the answer, full coverage is almost always the better option, because fixed costs get spread out. The third is unspectacular: no extras without a concrete benefit. Every surcharge that brings no extra yield or added value directly lowers the return.
In consultations we regularly see both extremes: prospective clients who wave it off because of a pessimistic blanket figure from the internet – and competitors' quotes in which a double-digit return is «guaranteed». Both rarely survive a recalculation. When we calculate with the real consumption data and the municipality's tariffs, the result is almost always somewhere in between: less spectacular than the promise, significantly better than the scepticism.
Frequently asked questions
Can the return be compared with a savings account?
Only to a limited extent. The solar system ties up capital long-term, its yield depends on electricity prices, and part of the value lies in the independence from price fluctuations. For investment decisions, the assessment belongs in the context of your overall situation – that's a matter for your financial advisor, not a solar guide.
What happens to the return if electricity prices fall?
Falling grid purchase prices reduce the most important income item and lengthen the calculation; rising ones shorten it. Anyone who calculates conservatively with today's tariffs is prepared for both.
Does a storage battery improve the return?
It raises the self-consumption rate, but costs extra – whether the result improves depends on the consumption profile. The assessment: Is a battery storage system worthwhile?
Do I have to pay tax on income from feed-in?
The tax treatment of feed-in revenue and investment deductions differs by canton. The basics are explained in the article Tax deduction for solar systems; your tax office's practice is authoritative.
How reliable are online return calculators?
Useful as a first orientation, nothing more. Most work with average assumptions for consumption profile and tariffs – precisely the figures that vary the most in an individual case.
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Swissolar-certified specialist company · ESTI installation authorisation (Art. 14 NIV) · in Zurich since 2017 · over 150 systems completed · a personal answer from the specialist company, no call centre
Sources: Swiss Federal Office of Energy SFOE, EnergieSchweiz, ElCom (electricity price overview), Pronovo.
Last updated: 9 July 2026 · Author: ecoEn editorial team
