Background
#The PV tax deduction in Solothurn is generally possible for existing buildings because photovoltaics count as an energy-saving and environmental-protection measure; for new builds and replacement new builds, however, the Canton Solothurn tax manual sets a clear 5-year boundary.
What matters is not only the system itself, but whether you claim actual property costs and separate your own costs cleanly from Pronovo EIV or other contributions. For electricity storage, the Solothurn tax court changed its practice in its judgment of 23 May 2022: storage units combined with renewable energy generation can be deductible, except for new buildings during the first five years.
For feed-in payments, Solothurn applies the net principle; the payment is taxable only to the extent that it exceeds the cost of electricity purchased from the grid. This page is professional guidance for project planning and does not replace an individual tax review by the competent authority or adviser.
What drives the economics
#The most important factor is the building age. The Solothurn tax manual treats new builds, replacement new builds and buildings completed within the last five years as non-deductible investments for income tax; the costs borne by the owner instead increase the investment costs for later real-estate gains tax.
For existing buildings, the deduction is tied to § 6 para. 1 StVO No. 16 and Art. 5 LKV: costs for measures that improve rational energy use or use renewable energy can be deducted for income tax. According to the tax manual, this also includes photovoltaic systems on or attached to existing buildings.
The flat-rate deduction blocks the PV costs. The tax manual states that energy-saving and environmental-protection measures are only considered under the actual-cost deduction; anyone choosing the flat-rate property-cost deduction cannot additionally claim the PV investment.
Incentives change the tax calculation. If the investment costs are deductible, subsidies and investment aid including the Pronovo EIV are taxed as other income; if they are not deductible because of new-build status, the contributions reduce the investment costs.
Illustrative calculation with explicit assumptions: existing residential building, actual-cost deduction, gross invoice of CHF 24,000, assumed Pronovo EIV of CHF 2,880 and another assumed contribution of CHF 1,000. Owner-borne cost: CHF 24,000 − CHF 2,880 − CHF 1,000 = CHF 20,120. In this example, the combined contributions of CHF 3,880 are also treated as other income; the simplified net effect on taxable income is therefore CHF 20,120 − CHF 3,880 = CHF 16,240. At an assumed marginal tax rate of 25%, that would imply CHF 4,060 less tax. This is not an individual tax calculation: tax brackets, other deductions, non-qualifying items and the treatment of the specific contributions can change the result.
Battery storage is not generally excluded in Solothurn. Following the tax court decision of 23 May 2022, storage units combined with renewable energy generation count as deductible energy-saving and environmental-protection measures, except for new buildings during the first five years.
For feed-in payments, Canton Solothurn applies the net principle. The payment for exported electricity is taxed only to the extent that it exceeds the cost of electricity purchased from the grid; according to the tax manual, self-consumed PV electricity does not increase the imputed rental value.
The process in seven steps
#Tick off for your project
Classify the building for tax purposes
before the quote, check whether the property is an existing building or whether new-build, replacement-new-build status or the 5-year boundary from the Solothurn tax manual applies. This classification decides whether the deduction matters for income tax or only through investment costs.
Prepare cost positions
have quotes and invoices separated by PV system, battery storage, bidirectional charging station, installation, electrical work and any roof work. The tax manual requires a traceable schedule for actual property costs; individual amounts from CHF 500 must be supported by invoice copies.
Keep incentives separate
record Pronovo EIV and any municipal or cantonal contributions separately from gross costs. In Canton Solothurn, building-programme funding applications must be submitted before construction starts; Pronovo EIV for PV runs through Pronovo, not through the cantonal energy office.
Create a tax worksheet for the quote
record the gross invoice, PV and storage items, non-qualifying work, Pronovo EIV, other contributions, invoice date and payment evidence on separate lines. This makes it possible to trace the owner-borne amount before filing the tax return and identify which invoices of CHF 500 or more need to be attached.
Plan the deduction year
under the Solothurn tax manual, the invoice date is generally decisive. If energy-saving and environmental-protection measures cannot be fully used in the invoice year because net income is negative, the remaining costs can be carried forward to two following tax periods.
Look at feed-in on a net basis
collect grid electricity costs and feed-in payments for the same tax year. Under Solothurn’s net principle, the feed-in payment is only taxed to the extent that it exceeds the cost of grid electricity purchased; whether the grid operator nets the amounts is not decisive.
Document the tax return
when claiming actual property costs, submit invoices, funding decisions, statements and, where useful, photos of the condition before and after the measure. For mixed works, the tax office may require an allocation between value-preserving and value-increasing portions.
Checked for your roof, not just read up on
Once the framing is clear, a property-specific check with roof, grid and documentation is worthwhile.
Frequently asked questions
#Sources
#The responsible authorities are decisive. Always verify binding details – amounts, deadlines and conditions – for your specific property against the current status of the respective authority.