Solar panel maintenance and lifespan

How long solar panels last

Solar panels have no moving parts. Because of that, they wear slowly. Energy Saving Trust says panels should last 25 years or more, and Home Energy Scotland says 30 years or more. The Northern Ireland government site nidirect says grid-connected systems need little maintenance.

Do not treat 25 or 30 years as a promise, though. Weather, roof movement and the quality of the original install all play a part, so results vary from house to house. Output also tends to fall a little each year as panels age. Our guide to solar panel lifespan and degradation explains how that slow loss works and what a performance warranty should say.

The panels are rarely the first part to fail. The inverter works hard every day, so it usually wears out sooner. We cover it below, because it is the part to plan for.

What upkeep a solar system needs

Most care is simple and visual. The MCS installation standard, MIS 3002 issue 6.0, includes an advisory maintenance schedule. It splits the checks into three tiers, so you know who does what: yourself, an intermediate visit and a full visit.

For a privately owned home, the standard suggests these gaps:

• You check by eye every year.
• An MCS contractor makes an intermediate visit every 10 years.
• An MCS contractor makes a full visit every 15 years.

These intervals are advisory only. System size, roof access and your insurer can all change them. Your installer must give you the checks you should do yourself, how often, and what to do if you spot a problem. These sit in your handover pack, so keep that pack safe.

Your yearly checklist

The MCS schedule lists the checks an owner can do. They need no tools and no ladder, since you can do them from the ground.

1. Look at the panels from the ground. Check for slipped or damaged panels and for heavy dirt.
2. Look at the inverter, where you can reach it safely. Check for a fault light or damage.
3. Confirm that your recorded generation is not falling.
4. Check for signs of strain on the roof, especially after heavy winter snow.
5. Trim back plants or trees that have grown to cast shade.

Shade matters more than most people expect. A branch that was clear when the system went in may shade a panel five years later. Even partial shade can cut output, although the effect depends on how the system is wired. Our post on solar panels in winter shows how low sun and short days make shading worse.

Cleaning your panels

In most cases rain keeps panels clean enough. Still, dirt, moss and bird mess can build up, especially on shallow roofs. nidirect says the main jobs are keeping panels clean and keeping tree shade under control.

The Energy Saving Trust suggests checking the panels from time to time and giving them a light clean if you can see dirt. It recommends a garden hose and a soft brush. It warns against a pressure washer, because that can damage seals and wiring.

Safety comes first. The MCS standard notes that solar work mixes the risk of a fall with the risk of electric shock. For that reason, do not climb onto the roof to clean. If the panels are out of reach, book a specialist, because they will have the right access gear. See cleaning and maintaining solar panels for more on methods, costs and timing.

MCS also says installers must advise you on protecting the system from plants and animals. Its examples include lichen, tree sap and nesting birds. If birds nest under your panels, ask your installer about proofing rather than poking about yourself.

The inverter: the part to plan for

The inverter turns the direct current from your panels into the alternating current your home uses. It runs whenever the sun shines. As a result, it is the most likely part to need replacing.

Energy Saving Trust says an inverter needs replacing after around 12 years, and its maintenance guide gives 10 to 15 years. That is well inside the life of the panels, so plan for it. Ask your installer three things before you buy:

• How long is the inverter warranty, and can it be extended?
• What would a replacement cost, including labour?
• Does the inverter have a fault log, and can the app show it?

Our guide to solar inverters explained covers string inverters, microinverters and optimisers. While each type does the same basic job, the type you choose can change how a failure affects your output. The how solar panels work hub also shows where the inverter sits in the system.

Warranties and guarantees

A solar job has more than one warranty, and each one covers a different thing. It helps to keep them apart.

• Workmanship guarantee. This covers the installer’s work, such as roof fixings and wiring.
• Product warranty. This comes from the maker of the panels or inverter.
• Performance warranty. This is the maker’s promise on how much output the panels will still give after a set number of years.

For homes, MCS says an insurance-backed guarantee is mandatory. It must cover workmanship for at least two years. It must pass to the next owner if you sell the house. It can run for up to 10 years in total, but never longer than the guarantee your installer offers. RECC members must also give you an insurance-backed workmanship warranty once the job is done.

An insurance-backed guarantee matters if your installer stops trading. In that case the policy, not the firm, picks up the cover, which is why it is worth checking early. Our guide to choosing a solar installer explains how to check this before you sign.

Keep all your papers together. That means the MCS certificate, the handover pack, the guarantee and the product warranties. A buyer will want to see them when you sell, because the guarantee can pass to them.

Keeping an eye on output

Monitoring is the easiest maintenance tool you have. Most inverters link to an app that shows daily generation. However, you only spot a fault if you look, so a sudden drop on a sunny day is worth a check.

The MCS schedule makes the same point in two ways. It asks owners to check that recorded generation is not falling. It also asks a visiting contractor to check that generation matches the prediction. Remember that the performance estimate you were given is guidance for the first year only. It is not a guarantee.

Our post on reading your solar monitoring app shows what the graphs mean and which patterns point to a fault. If you plan to add a battery later, see batteries and export for how it changes the picture.

What good care does for your money

Light upkeep protects the return on your install, because panels that are clean, unshaded and checked yearly give you the output you paid for. A replacement inverter is a cost to put in your sums from the start. Our post on whether solar panels are worth it looks at that long-term view. The costs and savings hub shows how upkeep fits into the wider budget.

Your roof matters as well. The MCS standard says a system should not harm the weather-tightness of the building for the life of the system. If your roof is old, think about repairs before you fit panels. Taking panels off later to re-roof costs money. See roof and property suitability for what to check first.

If you rent, sell or move

Maintenance looks a little different when the home changes hands. The paperwork matters most here.

If you sell, the buyer will want proof that the system was installed to standard. The MCS certificate and the handover pack give that proof. The insurance-backed guarantee must also pass to the new owner, so hand over the policy details with the house.

If you rent the property out, the MCS schedule changes. For a rented home it drops the yearly owner check. It lists an intermediate visit every five years and a full visit every 10 instead. Those figures are advisory, yet they show why a landlord may want a regular look by someone who knows the system, because tenants rarely check it.

If you buy a home that already has solar, ask the seller for the same papers. Then check that the inverter warranty has not run out. An old inverter may be close to the end of its life, and that cost lands on you.

When to call a professional

Call your installer, or a qualified electrician, if you see any of these:

• A fault light or error code on the inverter that does not clear.
• A sudden, lasting drop in output on clear days.
• Cracked glass, loose panels or cables hanging down.
• Water coming in near the roof fixings.
• Strange smells, heat or noise from the inverter.

Check your guarantee first, because a repair by someone else could affect it. Prices, standards and manufacturer terms change, so we recheck the sources on this page from time to time. This version was reviewed in October 2026.