Solar Calculator Spain 2026

Autoconsumo in Spain: cheap installs, capped surplus payments

Spain's rooftop market boomed after Royal Decree 244/2019 killed the old 'sun tax' and legalised simplified surplus compensation (compensación simplificada de excedentes). Combine 4.3–4.6 kWh/kW/day of sunshine with some of Europe's lowest installed prices — roughly €1.20–1.60 per watt for a typical home system — and payback periods of 5–7 years are realistic, shorter still where town halls add tax rebates. The defaults above use €0.18/kWh, 4.4 sun-hours and €1.40/W; refine production for your province with the solar output calculator.

How surplus compensation actually pays

Under the simplified mechanism your retailer credits each exported kWh on the monthly bill, usually at €0.05–0.11/kWh depending on your contract (PVPC customers get an hourly market-linked price, often near the low end at midday). Two rules matter:

• The credit can never exceed the energy term of that month's bill — excess surplus is simply lost, with no rollover to the next month.
• Compensation applies to installations up to 100 kW; larger surpluses must be sold on the market instead.

Because exported energy earns roughly a third of what imported energy costs, shifting dishwashers, EV charging and water heating into daylight hours is the single biggest lever on your return. The calculator's self-use slider models exactly this — and the battery payback calculator shows whether a battery beats giving surplus away.

Municipal incentives: IBI and ICIO

Hundreds of municipalities discount the IBI property tax by 25–50% for 3–30 years after installing solar, and many rebate up to 95% of the ICIO construction tax. These local bonuses can shave one to two years off payback but vary street by street, so check your ayuntamiento's ordinance and the IDAE/CNMC guidance before counting on them.

Worked example: 4 kW in Valencia

A 4 kW array at 4.4 sun-hours yields about 6,400 kWh/year. Self-consuming 45% at €0.18/kWh saves €518; exporting the rest at €0.06/kWh (within the bill cap) adds about €211. Against a €5,600 install, that is roughly a 7.7-year simple payback — closer to 6 with a 50% IBI rebate. Test your own tariff in the savings calculator and right-size the array with the system size calculator so surplus does not outgrow the bill cap.

Caveats: midday wholesale prices increasingly dip toward zero, squeezing surplus value, and PVPC pricing changes with the market. Verify current rules with the CNMC and your retailer. For contrast with a premium-tariff, low-sun market, see the Germany solar calculator.

Solar calculators for other countries

Localized subsidy and tariff math for more markets:

Frequently asked questions

Typically 0.05-0.11 euro/kWh. Free-market contracts fix a price, while PVPC customers receive an hourly market-linked value that can fall very low on sunny middays. The monthly credit can never exceed the energy term of your bill, and unused surplus does not roll over.

No. The charge on self-consumed energy was abolished in 2018, and RD 244/2019 introduced the current simplified compensation framework. Installations up to 100 kW with surplus compensation face no tolls on self-consumed energy.

Many municipalities cut the IBI property tax by 25-50% for anywhere from 3 to 30 years, and rebate up to 95% of the ICIO construction tax on the installation permit. Amounts and durations are set locally, so check your ayuntamiento's current ordinance before budgeting.

Increasingly, yes. Because surplus earns roughly a third of the retail price and is capped at your bill, storing midday energy for evening use raises the effective value per kWh from about 0.06 to 0.18 euro. Whether that beats the battery's cost depends on your load profile - run the numbers before buying.

About 13 kWh a day or 4,862 kWh a year on average, from about 10.2 a day in December to 15.9 a day in July, according to PVGIS data for panels at the best fixed angle. Shading, dust and orientation change the result.