Principle: a solar installation = energy savings costs
In Switzerland, the Federal Law on Direct Federal Tax (LIFD) and cantonal laws allow costs to save energy or use renewable energy to be deducted. A photovoltaic installation, a storage battery or an energy monitoring system fall into this category. The deduction applies to taxable income — not the tax itself.
Direct federal tax (IFD): check the treatment of the existing building
For existing buildings, investments intended to save energy or use renewable energies can be admitted according to federal and cantonal tax rules. New construction, aid received and the private/professional portion may change the calculation: keep the supporting documents and have the treatment validated if the amount is large.
Cantonal and municipal taxes: the real opportunity
This is where the main tax advantage lies. Most cantons allow owner-occupiers to deduct energy investments as extraordinary maintenance costs in their cantonal declaration. VD example: deduct the investment in the “property income conservation costs” form (F-IC, energy saving works section). GE example: annexed declaration for real estate work costs (ICC).
Calculation of tax savings
Simplified example, subject to tax eligibility: CHF 16 000 in expenditure minus CHF 3 000 in grants gives CHF 13 000 in eligible costs. With an assumed marginal tax rate of 30%, the tax saving is CHF 3 900. Deduct grants before calculating the deduction; do not count the same benefit twice.
What is deductible: precise list
Itemise panels, inverter, storage, mounting, cabling, connection and labour on the invoice. Eligibility depends on the rules applicable to the building and canton. Roof work can constitute maintenance, improvements or energy measures: classify it separately rather than automatically treating it as deductible or non-deductible.
From 2029: new tax reform
The reform takes effect on 1 January 2029. It removes the federal deduction for energy-saving measures; cantons can retain certain deductions for a limited period. Distinguish an investment under current rules from a project planned from 2029 and check the cantonal treatment before signing.
How to declare it: practical points
1. Obtain an itemised VAT invoice from your installer. 2. Keep the Pronovo confirmation and installation report. 3. Declare the tax-eligible net costs after deducting grants under the applicable property maintenance or energy-saving category. 4. Provide invoice evidence as required. Ask your tax authority to confirm the eligible amount and supporting documents.