What does this solar calculator do?
Solar is one of the few energy investments where you do not need to speculate. The sun is there, the system produces, the savings are real. But identical systems pay off completely differently depending on country, subsidies and self-consumption profile. Our calculator addresses exactly that: country-specific math, current May 2026 subsidy programs, realistic self-consumption rates, and a Brent sensitivity that no other solar calculator has.
Concretely we calculate for your system: annual yield in kWh (based on kWp, orientation, tilt and country-specific yields), self-consumption savings (at your electricity price), feed-in revenue (at current EEG/EAG/EIV/Compensación tariff), subsidies (KfW VAT-exemption in DE, federal states in AT, Pronovo-EIV in CH, IDAE in ES), payback time (simple and real with 0.5% module degradation and 2% electricity price inflation per year) and 25-year ROI.
Additionally we model the Brent sensitivity: when oil prices rise, electricity prices follow (pass-through factor 0.3% per USD), your self-consumption savings increase, payback time shortens. That is the USP. No other solar calculator links live energy prices.
Calculate solar payback now
The wizard asks you 6 questions about country, system size, roof, electricity price, storage and investment. Takes around 90 seconds. All inputs stay locally in your browser, no login, no email required.
Subsidies + feed-in tariffs 2026 in DE/AT/CH/ES
Germany, KfW + 0% VAT + EEG feed-in
The main subsidy for small PV in Germany since 2023 is the 0% VAT on systems up to 30 kWp. The feed-in tariff is 7.78 cents per kWh for partial feed-in (up to 10 kWp) and 12.34 cents for full feed-in, as of February 1, 2026. Important 2027: The fixed EEG feed-in tariff is to be abolished for new small PV systems from January 1, 2027. Systems commissioned in 2026 keep their 20-year fixed tariff.
Austria, 20% VAT + state-level subsidies
The 0% VAT exemption in Austria expired on April 1, 2025. State-level subsidies vary strongly: Vienna started a 7-million-euro package on May 1, 2026 with up to 150 euros per kWp PV and 150 euros per kWh storage. Feed-in via OeMAG at market prices (typically 8-10 cents per kWh).
Switzerland, Pronovo EIV + cantonal extras
Switzerland uses one-time payment (EIV) via Pronovo instead of running tariffs. For small systems under 100 kWp 2026: CHF 350 base + CHF 320 per kWp from 2 kWp. A typical 10-kWp system gets CHF 3,550. Plus cantonal extras 200-800 CHF per kWp depending on canton.
Spain, IDAE + IRPF + IBI
Spain subsidizes via the IDAE program for small PV with 300-1,100 euros per kWp residential, average around 600 EUR per kWp. Plus IRPF tax deduction 60% up to 3,000 euros, plus IBI municipal bonus. Compensación por Excedentes at spot prices (5-7 cents per kWh).
How we calculate: methodology with 9 data sources
Specific yield per country
South-optimal values at 35-degree roof tilt: Germany 950 kWh/kWp, Austria 1,050, Switzerland 1,080, Spain 1,450 kWh/kWp per year. Data basis: PVGIS (EU Commission), DWD solar irradiation data, SwissSolar, IDAE Atlas Spain.
Orientation and tilt factors
South = 100%, SE/SW = 96%, East/West = 85%, NE/NW = 72%, North = 60%. Tilt 25-40 degrees optimal (100%), 15-25 = 96%, flat (0-15) = 88%, steep (over 55) = 90%.
Electricity prices per country
DE: 32 ct/kWh household price (Federal Network Agency cap April 2026). AT: 28 ct/kWh. CH: 32 Rappen/kWh. ES: 20 ct/kWh PVPC variable.
Pass-through factor Brent to electricity
0.3% per USD Brent delta. Electricity reacts weaker than heating oil (1.1%) because the electricity mix is more diverse (wind, solar, nuclear, coal, gas). See methodology hub.
What happens when Brent rises +20 USD?
Solar profits indirectly from a Brent rise through pass-through on electricity prices. We use a conservative pass-through factor of 0.3% per USD Brent delta. Example: at current Brent 75 USD, electricity 32 ct/kWh. At a Brent rise to 95 USD (+20 USD), electricity rises to ~33.9 ct/kWh (+6%). On an 8-kWp system with 30% self-consumption and 7,600 kWh annual yield this adds 43 euros per year in self-consumption savings, over 25 years adds 1,080 EUR ROI.
Pratfall: Solar is less Brent-sensitive than heat pump or oil heating. But still a real hedge against electricity price escalation.
Country comparison: where does solar pay off fastest?
Example for an identical 8-kWp south-facing system with 7-kWh standard storage, 65% self-consumption rate, country-default values May 2026:
| Country | Annual yield | Investment | Subsidy | Payback |
|---|---|---|---|---|
| Germany | 7,600 kWh | ~17,450 EUR | 0% VAT | ~13 years |
| Austria | 8,400 kWh | ~17,500 EUR | ~1,200 EUR (Vienna) | ~12 years |
| Switzerland | 8,640 kWh | ~22,300 CHF | ~2,910 CHF Pronovo | ~11 years |
| Spain | 11,600 kWh | ~14,050 EUR | ~4,800 EUR (IDAE) | ~5-6 years |
Spain wins clearly through Mediterranean sun yield (+50% vs DE) plus IDAE subsidy.
Frequently asked questions about solar payback 2026
How long is solar payback in 2026?
Is a battery worth it in 2026?
What about the German feed-in tariff in 2027?
When does solar NOT pay off?
Sources + methodology
- DE EEG tariff: Federal Network Agency, February 1, 2026 data
- DE 0% VAT: Section 12 (3) UStG (small PV up to 30 kWp since 2023)
- AT Vienna May 2026: wien.gv.at photovoltaic-funding-package
- CH Pronovo EIV: pronovo.ch, single-payment rates 2026
- ES IDAE: idae.es, self-consumption aid 2025-2026
- Specific yields: PVGIS (EU Commission)
- Pass-through methodology: /en/methodology/pass-through-effect/
Disclaimer: Subsidy amounts and feed-in tariffs are May 2026 status and can change. Before installation always check current conditions directly at KfW, OeMAG, Pronovo or IDAE.
More calculators
- All German calculators (KfW-458 Heat Pump DE/AT/CH, CO2 Heating Oil, Heating Comparison)
- Pass-Through Methodology