Free tool, no sign up
Solar savings calculator
Pick your municipality and enter your monthly bill. The calculator sizes a system to your consumption, uses the PVGIS yield for your municipality and shows the yearly saving, the surplus income and the payback, as ranges from published figures. For a real price, ask installers for quotes.
Benefit per year, Lisboa
€430
30% of the bill
- Estimated consumption
- 4,000 kWh a year
- System size
- 2.5 kWp
- Yearly production
- 3,980 kWh
- Share of production you use
- 30%
- Saving on the bill
- €290 a year
- Surplus sold (2,780 kWh)
- €140 a year
- Indicative price
- €3,750 to €5,000
- Payback
- 9 to 12 years
ADENE and DGEG consider a payback under 7 years acceptable.
| Month | Production | Average consumption |
|---|---|---|
| Jan | 239 kWh | 333 kWh |
| Feb | 269 kWh | 333 kWh |
| Mar | 336 kWh | 333 kWh |
| Apr | 351 kWh | 333 kWh |
| May | 392 kWh | 333 kWh |
| Jun | 387 kWh | 333 kWh |
| Jul | 425 kWh | 333 kWh |
| Aug | 424 kWh | 333 kWh |
| Sep | 378 kWh | 333 kWh |
| Oct | 307 kWh | 333 kWh |
| Nov | 235 kWh | 333 kWh |
| Dec | 234 kWh | 333 kWh |
How it works
Consumption is your bill divided by the price per kWh: €0.24 with taxes, Eurostat's household price for Portugal in the second half of 2025, unless you enter your own. The system is sized so its yearly production matches your consumption, which is what ERSE asks owners to aim for; you can change the size.
Production is the PVGIS yield for your municipality, facing south at 35°. You use 20 to 40% of it yourself without a battery, depending on when you are home (Fraunhofer ISE); a battery roughly doubles that, up to 80% here. What you use saves the price on your bill; the surplus sells at about €0.05 per kWh on a fixed price contract.
The price uses the 2026 averages per kWp with VAT that 4gnews published for 3, 4 and 5 kWp, on a straight line between them, and Bave Energy's €3,500 to €4,500 for a 5 kWh battery. The estimate leaves out panel ageing, changes in electricity prices and maintenance.
Sources
- Eurostat, household electricity prices (nrg_pc_204), Portugal, 2,500 to 4,999 kWh a year, all taxes included, second half of 2025
- PVGIS, European Commission Joint Research Centre (yields per municipality, 1 kWp, 35° tilt, 14% losses, SARAH2 data for 2005 to 2020)
- Fraunhofer ISE, Recent Facts about Photovoltaics in Germany, version of 26 August 2026 (self consumption without and with a battery)
- Portal Energia, the surplus regime in 2026 (fixed price around €0.05 per kWh)
- 4gnews, home solar prices in 2026 from DGEG certified installers in Lisbon, Porto and Coimbra, turnkey, 23% VAT included, 30 July 2026
- Bave Energy, how much solar panels cost in Portugal in 2026, updated 5 June 2026 (battery prices; the page does not say whether VAT is included)
- ERSE, self consumption FAQ (FAQ do regime de autoconsumo), May 2025 (duties of the owner and the installer)
Ask for quotes you can compare.
Twelve quick choices, then your contact details. Free for you.