Solar Payback Calculator — Spain
Estimate your rooftop autoconsumo system's yearly production, electricity-bill savings, payback time and 20-year net profit. Defaults reflect a typical Spanish rooftop: €1,200/kWp installed, 1,500 kWh/kWp yield, €0.28/kWh grid electricity and €0.06/kWh compensación de excedentes.
1 · Your system
2 · Live results
yearly = self × price + exported × compensation20-year net ignores panel degradation, inverter replacement and electricity price changes — see the explainer below.
How solar payback works in Spain
A rooftop autoconsumo system earns money two ways: every kilowatt-hour you use yourself avoids buying grid electricity, and every surplus kWh you export is credited on your bill through compensación de excedentes (net billing with your retailer). Note the monthly bill can be reduced to zero energy cost, but never negative — unused surplus value is simply lost.
The formula
| Step | Calculation | Example (defaults) |
|---|---|---|
| Yearly production | kWp × yield | 8 × 1,500 = 12,000 kWh |
| Self-consumed | production × self-use % | 12,000 × 40% = 4,800 kWh |
| Exported | production − self-consumed | 7,200 kWh |
| Yearly value | self × price + exported × compensation | 4,800 × 0.28 + 7,200 × 0.06 = €1,776 |
| Payback | install cost ÷ yearly value | 9,600 ÷ 1,776 ≈ 5.4 years |
| 20-year net | yearly value × 20 − install cost | €25,920 |
Spain specifics
- Autoconsumo con excedentes: the standard regime — surplus is compensated on your bill at an agreed rate (typically €0.05–0.10/kWh), and your bill can't go below zero.
- Yield advantage: Spain's sun gives 1,400–1,700 kWh per kWp per year, among Europe's best — combined with lower install prices (~€1,200/kWp), payback is typically 4–7 years.
- Regional subsidies: many comunidades autónomas offer grants or IBI (property tax) rebates for solar — check your ayuntamiento, as these can cut payback further.
- Battery: raises self-consumption to 60–80% but adds several thousand euros; re-run the numbers with a higher self-use share and the battery cost included.
Frequently asked questions
What is compensación de excedentes?
It is Spain's net-billing scheme for autoconsumo: the surplus electricity your panels export to the grid is credited against your electricity bill at a rate agreed with your retailer (often around €0.05–0.10/kWh). The catch: the credit can only reduce the energy part of your bill to zero — you never get paid cash for leftover surplus, so oversizing the system wastes money.
Do I need permits or paperwork for a rooftop system?
Yes, but for typical residential systems it is straightforward: your installer handles the legalización with the regional industry authority and registers you with your distributor. Systems up to 15 kW are generally exempt from grid-access studies. Ask your installer for a fixed-price quote including all paperwork.
What self-consumption rate is realistic?
Without a battery, a typical household uses 30–50% of its own production; the rest is exported. With a home battery this rises to 60–80%. Higher daytime usage (home office, pool pump, air conditioning, EV charging at home) pushes the rate up for free.
How does orientation affect yield in Spain?
A south-facing roof in Spain yields roughly 1,500–1,700 kWh per kWp per year; east/west roofs yield about 15–20% less but produce more in the morning and evening — which can raise self-consumption. Heavy shading hurts disproportionately; a shaded section can drag down a whole string unless optimizers or microinverters are used.
Is a battery worth it in Spain?
It depends on your numbers. A battery shifts evening consumption to stored solar power, raising self-use from ~40% to ~65%+, but adds €4,000–8,000 to the install cost. Model it: add the battery cost to the installation price and raise the self-consumption share — if the payback time drops, it pays for itself. With low export compensation rates, batteries look more attractive.
Last updated: September 2026.
Disclaimer: True EV Cost tools are for information only and are not professional financial advice. Compensation rates, subsidies and electricity prices change — confirm current figures with your installer and retailer before investing.