How long do solar panels last? 25 to 30 years, and here is what wears out first

How long solar panels last in the UK: the short version

Pro-Fit's published guarantee is up to 25 years on panels and up to 12 years on batteries. Where a manufacturer's own warranty runs longer than that, the longer term is a bonus written into your quote, not a change to Pro-Fit's published cover. Every figure here is dated and sourced; your own warranty terms are the ones written into your quotation.

How solar panels age

Degradation: what the yearly loss is, why year one is different, and what the warranty line means

Every solar panel loses a small amount of output each year. This is normal: the silicon cells and the materials around them age slowly under sunlight, heat and weather. The most cited independent study of real-world panels, by the US National Renewable Energy Laboratory, reviewed thousands of degradation measurements and found a median loss of 0.5% a year, with a mean of 0.8% across the full spread of studies (Jordan and Kurtz, "Photovoltaic Degradation Rates, an Analytical Review," NREL report 2012, published in Progress in Photovoltaics 2013, https://docs.nrel.gov/docs/fy12osti/51664.pdf, read 7 October 2026). The extra loss most panels show in their first year, before settling onto the long-term curve, is a normal effect called light-induced degradation, as the cells adjust to real sunlight. It is expected, built into the warranty, and not a fault: almost every crystalline silicon panel settles the same way.

That NREL review measured panels built and installed well before today's product lines, many of them older cell technology than what is fitted now, and its median was 0.5% a year. DMEGC's warranty for its N-type series, the panels on Pro-Fit's published price list, allows 1% loss in the first year and 0.40% a year after, reaching 87.40% retained output at year 30 (DMEGC Limited Warranty DMW-STD02N-2026001). The gap between that 0.40% line and NREL's 0.5% median is the manufacturer's confidence in newer cell technology, not a looser floor: the warranty is still a floor, not a forecast.

What speeds up ageing

A handful of things make a panel age faster than the warranty curve assumes. Heat is the main one, which is one reason the UK's mild climate is kinder to panels than hotter markets, and humidity and damp take their toll on the seals and backsheet over the years. Fitting quality matters too: micro-cracks caused by poor handling, in the factory, in transport or on the roof, show up later as faster-than-expected loss. Long-term shading can cause hot spots, where the shaded cells run hotter and wear faster than the rest of the array, and a poorly designed system can suffer potential-induced degradation, a slow electrical effect that good system design avoids. On the coast, salt mist corrosion resistance (IEC 61701) is worth checking before you buy.

What a panel's warranty actually promises, and what it does not

A performance warranty guarantees a minimum output at a given year, backed by the manufacturer. It is not a promise the panel stops working the day the warranty ends, and it is not a guarantee of your electricity bill. Most panels keep generating well past their warranty period, at a lower output. The warranty is a floor, not a forecast, and claims go through the manufacturer, with your installer's help.

The inverter: the part that wears out first

Typical life and why electronics fail before glass does

A panel is mostly glass, aluminium and sealed silicon, built to sit outdoors for three decades. An inverter is power electronics, capacitors, fans and circuit boards doing continuous conversion work, which wears out sooner. The Energy Saving Trust puts it plainly: "if you have a solar inverter, you need to replace this after around 12 years" (Energy Saving Trust, "Solar panels" advice page, read 7 October 2026). Inverter manufacturers back their hardware with shorter terms than panel makers: Fox ESS's standard warranty for its Hybrid Series inverters is 60 months (5 years) from installation, extendable to 10 years in total if registered within 36 months of manufacture and connected to Fox Cloud monitoring (Fox ESS warranty policy, version 1.8, issued 3 January 2025).

String, hybrid and micro-inverters compared

A string inverter converts the output of a whole array from one box. A hybrid inverter does the same job but also manages a battery, which is why most new domestic systems use one. Micro-inverters sit behind each panel instead; they can help with mixed shading, but there are more of them to fail and each is harder to reach for a swap. For most domestic roofs, a single hybrid inverter is simplest to service and easiest to replace.

Signs an inverter is failing

Watch for an error code or fault light, a sudden drop in output on sunny days, no data reaching the monitoring app, or unusual fan noise or heat. Any of these is worth a call before the inverter fails completely.

How long do solar batteries last?

Cycles, depth of discharge and calendar ageing, in plain words

A battery wears in two ways at once: it ages with time, the way any battery does sitting on a shelf, and it wears with use, counted in cycles (one full charge and discharge) or total throughput. A battery charged and drained daily will usually hit its cycle limit before its time limit; one used lightly may do the opposite. Depth of discharge, how far down it is run each time, also affects wear, with shallower, more frequent cycles generally gentler than deep, infrequent ones.

Typical warranties

Two battery warranties, quoted from the manufacturers' own documents, are below.

• Sigenergy warrants its SigenStor battery to retain 60% of its usable energy after 10 years from installation, or an alternative throughput limit depending on the model, whichever comes first. The full 10-year term depends on the unit staying connected so Sigenergy can run remote firmware updates; if it stays disconnected for an extended period, Sigenergy says it may not be able to honour the full ten-year warranty, though it always provides a five-year warranty from the commence date (Sigenergy, Factory Limited Warranty for SigenStor, dated 16 April 2025, read 7 October 2026).
• Powervault states it plainly on its own FAQ page: "Our batteries are built to last and come with a 10 year warranty," across its P5, P4 and PV Compact ranges (Powervault, FAQs, read 7 October 2026).

Across these published warranties the common thread is a 10-year figure, with the small print, years, cycles, throughput, a guaranteed end-of-term capacity, or (for Sigenergy) a connectivity condition, differing by brand. Pro-Fit's published cover is up to 12 years, held by the manufacturer; the term for your battery is confirmed in your handover pack.

What shortens a battery's life, and what the inverter settings do to protect it

Running a battery flat to empty or full to the brim more often than needed, and high heat, both shorten its working life. A well-configured hybrid inverter protects against this from day one, limiting discharge depth and managing charge rates automatically, so the battery is worked gently rather than hard.

Fixings, cabling, isolators and bird protection: the small things that cause the big problems

The parts that rarely get mentioned cause a disproportionate share of real-world faults: loose roof fixings, cabling chafed where it passes through a penetration, a corroded isolator, or failed bird protection letting nesting material build up. None is expensive to fix early; left alone, any can cause a fault, water ingress, or a fire risk. This is what the 2-year Pro-Fit workmanship guarantee covers, and what a periodic inspection is there to catch.

Keeping a system healthy for 25 years

Most systems come with a monitoring app: glance at it monthly for a sudden, unexplained drop in generation on a sunny day, or a device that has stopped reporting, usually the first sign of a fault.

On cleaning, the Energy Saving Trust's guidance is straightforward: "In the UK, rain will clean your panels if they're tilted at 15 degrees or more" (Energy Saving Trust, read 7 October 2026). Most pitched roofs meet that angle, so most owners never need to clean their panels. Ground-mounted arrays, flatter roofs and dustier areas build up debris faster and may need an occasional clean.

A periodic check, every few years is typical, looks at the fixings, cabling, isolators, the inverter's fault log and the general condition of the array. Bird protection mesh stops nesting material building up underneath, which blocks airflow and can damage cabling, and moss on surrounding tiles is worth keeping in check too, since it holds damp against the roof.

Systems from 2010 to 2015: what to expect now

The installed base, and the common faults at 10 to 15 years

The UK's rooftop solar boom began under the Feed-in Tariff. A large share of the systems installed in that rush now sit in the 2010 to 2015 age band, at or past the point where the inverter, the first component due, needs a look.

If you installed panels in that window and have noticed lower output, a quiet inverter, or a monitoring app that stopped updating years ago, that points to an inverter reaching the end of its life, not a fault with the panels.

Signs a panel itself may need replacing

Occasionally it is the panel, not the inverter, reaching the end of its useful life. Look for visible delamination (cloudiness or bubbling under the front glass), discolouration or browning across a cell, a hot spot found during a thermal inspection, cracked glass or a corroded junction box, or output that stays well below the manufacturer's warranty line for its age once the inverter has been ruled out. A single failed panel can usually be swapped for a compatible model without replacing the whole array, though mixing an old and a new panel on the same string can pull the whole string down to the weaker panel's output, so a survey checks compatibility before any swap.

Replacing an inverter, adding a battery, or starting again

In most cases a failed inverter can simply be replaced, and a battery can often be added to the existing array at the same time, rather than starting again. What makes sense for a particular roof is a survey decision, not a rule of thumb.

What is guaranteed on a Pro-Fit system

Four separate cover periods run on a solar and battery installation and they are not held by the same party. Workmanship is ours and runs for two years. The panels, the battery and the inverter are the manufacturer's, and we handle those claims on your behalf. Every term is written into your quotation before you agree to anything.

• Workmanship, 2 years. Pro-Fit. Our installation, fixings, cabling and battery integration.
• Panels, up to 25 years. Manufacturer. Product and performance cover, depending on panel.
• Battery, up to 12 years. Held by the manufacturer. Cover confirmed in your handover pack.
• Inverter. Manufacturer. Warranty length stated on your quote.

What happens at the end of life

Solar panels are classed as electrical and electronic equipment under the UK's WEEE Regulations, specifically Category 14, PV panels (GOV.UK and Environment Agency, "Electrical and electronic equipment covered by the WEEE Regulations," last updated 12 August 2025). Producers and the wider supply chain carry a legal responsibility to see panels collected and recycled at end of life, rather than sent to landfill. A panel that has reached the end of its useful life is collected through a WEEE-registered recycling route, where the glass, aluminium frame and other materials are recovered for reuse.