A photovoltaic installation on an existing building can reduce your tax. Here is how it works, what it can amount to and what to check before committing.
On 28 September 2025, the Swiss people voted to abolish the imputed rental value. The effects on deductions for solar installations, and their timetable, depend on the federal implementing law and on each canton. Have the rule that applies on the date of your works checked, and do not rely on a deadline reported by a third party.
The cost of a solar installation on an existing building is, as a general rule, treated as a maintenance cost or an energy-saving measure: you can deduct it from your taxable income. It is not a refund: the deduction reduces the base on which your tax is calculated. Your saving is therefore the amount deducted multiplied by your marginal tax rate.
In principle, the building must already exist: an installation fitted on a new build is treated as an investment, not as maintenance. Grants received, such as the Confederation's one-off payment, are generally subtracted from the deductible amount. The detailed rules (age of the building, ceilings, supporting documents) depend on the canton.
The treatment of a battery varies from canton to canton, and often depends on whether it is fitted at the same time as the panels or later. We advise you to ask your canton's tax authority or your fiduciary before deciding.
The electricity you consume yourself is not income. What you feed into the grid and are paid for, however, may be taxable: how to declare it varies by canton. The Confederation's one-off payment is, depending on the case, income to be declared or a reduction of the deductible amount.
The deduction is made on your tax return, generally for the year of payment or commissioning, depending on the canton. The saving therefore arrives with your assessment, the following year. It is zero if you have no taxable income.
Example calculated with the same rules as our simulator: a 9.2 kWp installation (20 panels), for a net cost of 19'700 CHF after the federal grant.
| Your marginal tax rate | Estimated tax saving |
|---|---|
| 20% | ≈ 3'940 CHF |
| 30% | ≈ 5'910 CHF |
| 40% | ≈ 7'880 CHF |
Indicative estimate. The real saving depends on your taxable income, your canton and your situation.
| Canton | Installation deductible? | Battery | Where to check |
|---|---|---|---|
| Vaud | Yes, on an existing building, under conditions | To be confirmed with the tax authority | Cantonal tax administration (ACI) |
| Geneva | Yes, on an existing building, under conditions | To be confirmed with the tax authority | Cantonal tax administration |
| Valais | Yes, on an existing building, under conditions | To be confirmed with the tax authority | Cantonal tax service |
| Fribourg | Yes, on an existing building, under conditions | To be confirmed with the tax authority | Cantonal tax service |
| Bern | Yes, on an existing building, under conditions | To be confirmed with the tax authority | Cantonal tax office |
| Zurich | Yes, on an existing building, under conditions | To be confirmed with the tax authority | Kantonales Steueramt |
The information on this page is indicative. It must be reviewed by a fiduciary or a tax adviser and adapted to your canton and your situation. It does not constitute tax advice.
The simulator calculates an installation suited to your roof and an estimate of the tax saving, which you can adjust with your marginal rate.