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How Long Do Solar Panels Last?
Posted on 30th Apr 2026
How long do solar panels last is one of the first questions most Dorset homeowners ask before committing to an installation, and it’s a good one. Solar panels are a significant investment, so understanding what you’re actually getting for your money over the long term makes a lot of sense. The good news is that solar panels are genuinely one of the most durable and long-lasting home improvements you can make. Most modern systems will still be generating electricity long after they’ve paid for themselves many times over.
In Brief
Most solar panels are warrantied to last 25 to 30 years and keep generating well beyond that, degrading at a median rate of around 0.5% a year according to research from the National Renewable Energy Laboratory. That means a typical panel still produces 80 to 90% of its original output at the 25-year mark, rather than stopping when the warranty ends.
Here’s a thorough look at what to expect from your solar panels over their lifetime, what happens as they age, and what your options are when they eventually reach the end of their warranty period.
How Long Do Solar Panels Last?
The straightforward answer is that most modern solar panels are designed and warrantied to last 25 to 30 years. In practice, many will keep generating electricity well beyond that point. They don’t simply stop working when the warranty expires.
To put that in context, a system installed on a Dorset home today will still be producing electricity into the 2050s. Some panels installed in the UK during the 1990s are still generating power today, albeit at reduced efficiency.
It’s worth separating two things that often get conflated:
- Functional lifespan: how long the panel continues to produce electricity (often 30 years or more)
- Performance warranty period: the period during which the manufacturer guarantees a minimum output level (typically 25 years)
The panels don’t suddenly stop on day one of year 26. What the warranty period really tells you is the window during which the manufacturer stands behind the output figures. After that, the panels carry on, just without the formal performance guarantee.
Dorset’s climate is actually well-suited to panel longevity. Research consistently shows that high temperatures accelerate panel degradation, which is why systems in hotter countries degrade faster than those in the cooler, more temperate UK climate. A Dorset installation benefits from relatively mild temperatures compared to, say, Spain or Australia, which is good news for long-term performance.
What is Solar Panel Degradation?
Solar panels don’t fail overnight. Instead, they gradually become slightly less efficient over time, through a process known as degradation. Understanding this is important because it shapes realistic expectations about what your system will produce over the years.
Research from the National Renewable Energy Laboratory (NREL), one of the most respected sources of long-term solar performance data in the world, shows that modern, high-quality panels typically degrade at a median rate of around 0.5% per year. More recent field data from NREL’s 2024 PV Lifetime Annual Report, covering panels from manufacturers including Jinko, Trina, Q Cells and LONGi, found median degradation rates of between 0.3% and 0.6% per year for modern crystalline silicon panels.
What does that mean in practice? To give you a rough idea:
- A panel rated at 400W today will produce around 392W after five years (at 0.5% annual degradation)
- After 15 years, that same panel produces around 370W
- After 25 years, it’s producing around 330W, which is still very much a working solar panel
Most manufacturers’ performance warranties reflect this, typically guaranteeing that panels will still produce at least 80 to 90% of their original rated output at the 25-year mark.
The key takeaway is that degradation is gradual and predictable, not sudden. Your system will produce a little less each year, but the difference year-on-year is almost imperceptible, and the panels remain economically useful throughout.
Understanding Solar Panel Warranties
When you have solar panels installed in Dorset, you’ll receive two distinct types of warranty from the panel manufacturer. It’s worth knowing what each one covers.
Product warranty (typically 10 to 15 years)
This covers physical defects, manufacturing faults and premature failure. If a panel develops a fault or fails within this period through no fault of your own, the manufacturer should replace or repair it. Keep your installation paperwork, MCS certificate and product documentation in a safe place, as you’ll need them to make a warranty claim.
Performance warranty (typically 25 years)
This guarantees that the panel will still produce a minimum percentage of its original rated output throughout the warranty period. Most manufacturers now guarantee at least 80 to 90% of original output at 25 years, with some premium manufacturers offering even better guarantees than this.
One important point worth flagging: warranties can be voided by incorrect installation. This is one of several reasons why choosing an MCS-certified solar panel installer matters. The MCS certification scheme requires installers to meet specific standards, and using a certified installer is a condition of both warranty protection and access to the Smart Export Guarantee.
What About the Inverter?
The inverter is the part of a solar system that converts the DC electricity produced by the panels into the AC electricity your home actually uses. It’s also the component most likely to need attention before the panels themselves.
How long do inverters last?
- String inverters (the most common type in domestic installations) typically last 10 to 15 years, according to GreenMatch and industry data, meaning most homeowners will need to replace their inverter at least once over the lifetime of their solar panels
- Microinverters (fitted to each individual panel) tend to last considerably longer, with some manufacturers such as Enphase offering 25-year warranties that match the panel lifespan
- Hybrid inverters (used with battery storage systems) typically fall somewhere in between, lasting around 12 to 15 years with proper maintenance
What does inverter replacement cost?
Replacing a string inverter typically costs between £500 and £1,500 for a standard domestic system, including parts and installation, according to Upvolt Energy. It’s sensible to factor this into your long-term costings when you’re evaluating the economics of a solar installation. It’s a normal, planned piece of maintenance rather than a surprise failure.
The good news is that inverter replacement is also an opportunity to upgrade. By the time your original inverter needs replacing, newer models will likely be more efficient, and it’s a relatively straightforward moment to add battery storage capability if you haven’t already.
If you’re noticing a drop in system output and suspect the inverter might be the cause, Ace Energy’s repairs and maintenance team can carry out a health check and advise on whether repair or replacement is the right route.
What Happens to Solar Panels After 25 Years?
This is the question the title promises to answer, and the honest answer is rather reassuring. After 25 years, your panels don’t stop. They carry on generating electricity, just without the formal manufacturer performance guarantee behind them.
At that point, you broadly have three options:
1. Keep the system running as-is
For many homeowners this is the most sensible choice. The panels are long since paid off, the inverter may have already been replaced once, and the system is still generating meaningful amounts of free electricity. The cost of keeping it running is essentially zero. Many UK households are approaching this point now, having installed systems during the feed-in tariff era of the early 2010s, and most are choosing to keep their systems in service.
2. Add new panels alongside the existing ones
If your existing panels are still in reasonable working order but you want to boost output, perhaps because your electricity usage has increased, you’ve added an EV, or you want to power a heat pump, adding additional panels is a practical option. A surveyor can assess how the old and new panels can be integrated effectively.
3. Replace the full system
Panel efficiency has improved significantly since the early 2010s. A system installed today will typically produce considerably more electricity from the same roof space than one installed 15 years ago. If your existing system is heavily degraded or physically damaged, a full replacement with modern panels could be genuinely worthwhile, and the costs of solar installation have fallen considerably over the past decade.
A note on recycling
Solar panel recycling infrastructure is developing steadily in the UK. Panels contain valuable materials including silicon, silver, aluminium and glass, most of which can be recovered and reused. Under the Waste Electrical and Electronic Equipment (WEEE) Regulations, manufacturers and importers are responsible for funding the collection and recycling of panels at end of life, so there is a legitimate disposal route available when the time comes.
How to Maximise the Lifespan of Your Solar Panels
The good news here is that solar panels are genuinely low maintenance. They have no moving parts, sit outside in all weathers, and largely look after themselves. That said, there are a few things worth doing to keep your system performing well over the long term.
Keep them clean
Dust, moss, bird droppings and leaf debris all reduce output and, over time, can cause localised hotspots that accelerate degradation in affected cells. In Dorset, moss and lichen can be a particular issue on north-facing roof sections or panels with any shading. A clean with a soft brush and water once or twice a year is usually sufficient for most installations.
Annual health checks
A quick annual inspection, checking that connections are sound, no physical damage has occurred and the inverter is performing as expected, is good practice and can catch small issues before they become bigger ones. Ace Energy offers servicing and maintenance for solar PV systems across Dorset.
Watch for changes in shading
A tree that was a sapling when your system was installed might now be casting a significant shadow across part of your array for several hours a day. Even partial shading of one panel can affect the output of the entire string, depending on your system configuration. It’s worth reassessing shading periodically and cutting back any growth that’s encroaching on the panels.
Monitor your system output
Most modern solar systems come with monitoring apps that show daily, monthly and annual generation figures. Checking in regularly means that a sudden unexplained drop in output, which is usually the first sign that something needs attention, gets picked up quickly rather than going unnoticed for months.
Are Solar Panels Still Worth Installing in Dorset in 2026?
If you’re reading this while considering whether to install solar panels, the lifespan question feeds directly into the financial case.
A system installed on a south-facing Dorset roof today will typically pay back its installation cost in around 7 to 10 years, depending on system size, energy usage and how much of the generated electricity you use directly. That leaves 15 to 20 years of essentially free electricity generation within the 25-year warranty period alone, before factoring in any generation beyond that.
Over a full 25-year lifespan, the long-term savings are substantial. And with electricity prices having risen significantly over the past few years and the direction of travel unlikely to change, the value of generating your own electricity only increases over time.
It’s also worth knowing that Dorset homeowners with lower household incomes may be eligible for support through the government’s Warm Homes: Local Grant, which can cover the full cost of solar installation for eligible households. Your local council administers this, so it’s worth checking whether the scheme is currently open in your area.
For a full picture of the financial case, our post on whether solar panels are worth it in Dorset goes into more detail on costs, savings and payback periods.
Frequently Asked Questions About Solar Panel Lifespan
Do solar panels degrade over time?
Yes, but very gradually. Research from NREL shows a median degradation rate of around 0.5% per year for modern crystalline silicon panels. After 25 years, most panels still produce 80 to 90% of their original rated output.
How long does a solar inverter last?
String inverters typically last 10 to 15 years and will likely need replacing at least once over the lifespan of your panels. Microinverters tend to last considerably longer, with some carrying 25-year warranties. Replacement costs typically range from £500 to £1,500.
What happens to solar panels after 25 years?
They carry on generating electricity, just without the formal manufacturer performance guarantee. Most homeowners choose to keep their systems running, as the panels are paid off and still producing useful amounts of free electricity.
Are solar panels worth it over their lifetime?
For most Dorset homeowners, yes. With a typical payback period of 7 to 10 years and a warranted lifespan of 25 to 30 years, you can expect 15 to 20 years of essentially free electricity generation within the warranty period alone, plus continued generation beyond it.
How do I know if my solar panels need replacing?
The most common signs are a sustained and unexplained drop in output that isn't explained by weather or shading, visible physical damage to panels, or an inverter that's producing error codes or failing to start. An inspection from a qualified installer can quickly establish whether the issue is with the inverter, the panels, or elsewhere in the system.
If you’re thinking about solar panel installation in Dorset or want a health check on an existing system, get in touch with the Ace Energy team for a free, no-obligation survey. We’re MCS-certified, cover the whole of Dorset and Wiltshire, and can give you a clear picture of what a system would generate and save at your specific property.
