Solar panels can change a home’s electricity use and energy costs, but they do not show on their own how much the property will sell for. Location, condition, local demand and the terms of a sale also matter. There is no universal percentage that guarantees a higher sale price after installing panels.
Check what system is included in the sale
Ask whether the panels and inverter belong to the seller or are covered by a lease, finance plan or other contract. Request invoices and installation documents, warranties, manuals, repair records and monitoring data. Clarify who controls the app account and what is needed to transfer it. Check whether the installation documentation is complete and whether the system works as described in the listing.
Assess performance using real records
If available, ask for at least twelve months of generation and consumption data, along with bills or settlement statements that show how exported electricity is credited. Separate the electricity generated, used in the home and sent to the grid. Any benefit depends on household habits, tariffs, orientation, shading, equipment condition and export arrangements; a sales estimate is not a guarantee of each household’s results.
Review the energy certificate separately
A building’s energy rating is calculated using a recognised procedure and information about its features and installed systems. It does not update automatically when panels are fitted, and a solar installation does not guarantee a particular letter grade. If the rating matters to the transaction, ask a qualified professional to check the current certificate and explain what result the applicable method could produce.
Compare like-for-like properties
When comparing homes, match location, floor area, condition and other features as closely as possible. Share the installation documents and measured results so the buyer and their professional adviser can assess them. For a specific sale price, use an independent valuation rather than adding a fixed amount for each installed kilowatt.
Spain’s MITECO lists the recognised procedures for building energy certificates, with certificate models updated on 30 September 2026. See also Royal Decree 390/2021 on energy certification. To assess residential solar, see our home solar service.