Data study
Solar + EV
Payback Index 2026.
Where does a home solar system pay for itself fastest when it's charging your car? We ran the same reference setup — a VW ID.4 driving 15,000 km a year — through 22 European countries using our own engine and real PVGIS satellite irradiance. Every value is in EUR so the countries compare like-for-like.
Last updated
| # | Country | Panels | Annual yield | Annual savings | Payback |
|---|---|---|---|---|---|
| 1 | ItalyRome | 6 | 3,469 kWh | €697 | 4 yrs |
| 2 | PortugalLisbon | 5 | 3,013 kWh | €526 | 4 yrs |
| 3 | GreeceAthens | 5 | 3,053 kWh | €499 | 4 yrs |
| 4 | SpainMadrid | 5 | 3,140 kWh | €467 | 4.3 yrs |
| 5 | DenmarkCopenhagen | 8 | 3,122 kWh | €828 | 5.4 yrs |
| 6 | NetherlandsAmsterdam | 8 | 3,049 kWh | €768 | 5.6 yrs |
| 7 | IrelandDublin | 9 | 3,251 kWh | €868 | 5.6 yrs |
| 8 | United KingdomLondon | 8 | 3,034 kWh | €718 | 5.8 yrs |
| 9 | RomaniaBucharest | 6 | 2,988 kWh | €365 | 5.9 yrs |
| 10 | GermanyBerlin | 8 | 3,155 kWh | €745 | 6 yrs |
| 11 | BelgiumBrussels | 8 | 3,121 kWh | €680 | 6.1 yrs |
| 12 | AustriaVienna | 7 | 3,099 kWh | €558 | 6.5 yrs |
| 13 | CroatiaZagreb | 7 | 3,330 kWh | €442 | 6.7 yrs |
| 14 | SwitzerlandBern | 7 | 3,269 kWh | €659 | 6.8 yrs |
| 15 | CzechiaPrague | 8 | 3,289 kWh | €492 | 6.8 yrs |
| 16 | FranceParis | 7 | 3,014 kWh | €474 | 7.1 yrs |
| 17 | PolandWarsaw | 8 | 3,154 kWh | €428 | 7.1 yrs |
| 18 | SerbiaBelgrade | 6 | 2,899 kWh | €286 | 7.1 yrs |
| 19 | HungaryBudapest | 7 | 3,258 kWh | €352 | 8 yrs |
| 20 | FinlandHelsinki | 8 | 2,926 kWh | €386 | 10.8 yrs |
| 21 | NorwayOslo | 9 | 3,216 kWh | €406 | 11.5 yrs |
| 22 | SwedenStockholm | 8 | 2,939 kWh | €329 | 12.2 yrs |
Methodology
How the ranking is built.
Every country runs the exact same reference system, so the only things that change are its location's sunlight and its local economics. Panel count is sized to cover the EV's annual energy demand at that location — not capped by roof area. Payback is the install cost divided by annual savings (self-consumed solar valued at the local electricity price, exported surplus at the local feed-in tariff).
Why these paybacks are faster than the “official” ones
This index assumes an EV that soaks up the daytime solar production, so roughly three quarters of every kWh generated is used on-site (valued at the retail electricity price) and only the rest is exported at the lower feed-in tariff. That split is not fixed: it follows how large the array is against the car's demand, and the reference system here is sized to the car. A typical household without an EV self-consumes far less and exports more, so its payback is slower. That's the whole point of pairing solar with an EV — the payback here is deliberately shorter than a car-free household's, not an error. Compare like-for-like: an EV-charging scenario, not a generic rooftop one.
All values are in EUR for cross-country comparability — non-euro electricity prices, install costs, and feed-in tariffs are converted at mid-2026 exchange rates before the calculation. Irradiance comes from PVGIS (EU Joint Research Centre) for each country's capital city; the per-country electricity price, install cost, and feed-in tariff come from our own maintained tables.
Solar irradiance for each capital city — 25 years of satellite measurements.
Electricity price, install cost per kWp, and feed-in tariff by country (2024–2026).
Grid carbon intensity by country, injected alongside irradiance.
This is a fixed reference comparison, not personalised advice — your own payback depends on your address, roof, car, and mileage. Run your exact numbers in the planner.
Your numbers, not the average
This index is a fixed reference. Yours will differ.
Your payback depends on your exact address, roof, car, and mileage. Run the same calculation on real satellite data for your own location — free, no account.
Calculate this for your own address and car →