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 | 5 | 3,180 kWh | €764 | 3.3 yrs |
| 2 | RomaniaBucharest | 6 | 3,287 kWh | €710 | 3.3 yrs |
| 3 | GreeceAthens | 5 | 3,359 kWh | €620 | 3.5 yrs |
| 4 | SpainMadrid | 5 | 3,454 kWh | €590 | 3.7 yrs |
| 5 | PortugalLisbon | 5 | 3,314 kWh | €559 | 4.1 yrs |
| 6 | PolandWarsaw | 7 | 3,036 kWh | €686 | 4.3 yrs |
| 7 | AustriaVienna | 6 | 2,922 kWh | €693 | 5 yrs |
| 8 | IrelandDublin | 8 | 3,178 kWh | €940 | 5.1 yrs |
| 9 | BelgiumBrussels | 7 | 3,004 kWh | €776 | 5.2 yrs |
| 10 | GermanyBerlin | 7 | 3,036 kWh | €776 | 5.6 yrs |
| 11 | CzechiaPrague | 7 | 3,166 kWh | €578 | 5.6 yrs |
| 12 | United KingdomLondon | 7 | 2,920 kWh | €699 | 5.7 yrs* |
| 13 | CroatiaZagreb | 6 | 3,140 kWh | €452 | 6.1 yrs |
| 14 | SwitzerlandBern | 6 | 3,082 kWh | €634 | 6.7 yrs* |
| 15 | FranceParis | 7 | 3,315 kWh | €546 | 6.8 yrs |
| 16 | SerbiaBelgrade | 6 | 3,189 kWh | €332 | 6.8 yrs |
| 17 | NetherlandsAmsterdam | 7 | 2,934 kWh | €605 | 6.9 yrs |
| 18 | HungaryBudapest | 6 | 3,072 kWh | €383 | 6.9 yrs |
| 19 | SwedenStockholm | 8 | 3,233 kWh | €612 | 7.2 yrs |
| 20 | DenmarkCopenhagen | 7 | 3,005 kWh | €525 | 8.2 yrs |
| 21 | FinlandHelsinki | 8 | 3,218 kWh | €541 | 8.5 yrs |
| 22 | NorwayOslo | 8 | 3,145 kWh | €358 | 12.8 yrs |
* Electricity price estimated by VoltSun — Eurostat publishes none for this country.
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 electricity price is Eurostat's household price (Serbia: our tariff model, checked against real bills; the UK and Switzerland: our own estimate, marked with an asterisk). Install cost and feed-in tariff come from our own maintained tables.
Solar irradiance for each capital city — 25 years of satellite measurements.
Household electricity price, all taxes included (nrg_pc_204, 2026-S1, 5,000–14,999 kWh a year). Serbia is priced from VoltSun's tariff model, reproduced against real EPS bills.
Install cost per kWp and feed-in tariff by country (2024–2026), and the electricity price for the UK and Switzerland, which Eurostat does not cover.
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 →