Panels last longer than almost anything else bolted to a British house, and their output declines slowly and predictably rather than failing suddenly. The parts with shorter lives are the inverter and, on a badly detailed installation, the roof penetrations. The house value question is a separate one, and the honest answer to it is less confident than the marketing.
What the warranty actually promises
Panels normally carry two separate warranties: a product warranty against defects, and a performance warranty guaranteeing a minimum percentage of original output after a stated number of years. That second one is the real statement about lifespan: it accepts that output declines gradually and puts a floor under it. An array at the end of a performance warranty is not finished, it is producing somewhat less than new, and many keep going well beyond. Read both warranties and check who holds them and whether they transfer with the house.
What actually ends an array's life
Rarely the panels. More often it is the roof underneath needing replacement, an inverter failure on an old system where replacement is no longer economic against a modern array, physical damage, or a house sale where the new owner wants it gone. Water ingress at badly detailed fixings is the failure that damages the building rather than the system, which is why the roofing competence of the installer matters as much as the electrical competence.
Do solar panels increase home value? The honest answer
Buyers value an owned, well documented, efficient array, and surveys periodically put numbers on it. Those numbers vary widely by study, by region and by period, and they are averages across markets rather than a figure for your house. What is more reliable is the negative: an array with missing paperwork, an unclear ownership position or a lease attached to the roof can slow a sale and put buyers off. Owning it outright with the certificates in a folder is the version that adds value; the rest is contested.
EPC ratings and what solar does to them
An Energy Performance Certificate is produced by a modelled assessment, and a photovoltaic array is one of the measures that assessment takes into account, so an array generally improves the rating. How much depends on the property and the rest of its fabric, and an EPC is a model rather than a measurement, so it is not a reliable proxy for actual bills. For landlords and for buildings subject to minimum energy standards, the rating is a practical reason to install in its own right.
Questions people ask about solar panel lifespan
How long do solar panels last on a roof?
Longer than most of what is fixed to a house. The meaningful statement is the performance warranty, which guarantees a minimum share of original output after a stated number of years, and many arrays continue producing beyond that with gradually reduced output.
Do solar panels lose output over time?
Yes, slowly and predictably. Manufacturers publish an annual degradation rate and back it with a performance warranty. It is a gradual decline rather than a failure, and it is worth comparing between quoted modules.
Do solar panels add value to your house?
Evidence points to owned, documented arrays being valued by buyers, with figures varying widely by study and market. The clearer effect is negative: missing paperwork or a lease attached to the roof can deter buyers and slow a sale.
Do solar panels improve an EPC rating?
Generally yes, because the assessment takes generation into account. How much depends on the rest of the property's fabric, and an EPC is a model rather than a measurement of your actual bills.