Solar panel maintenance is light work: clean the panels every 12–18 months (rain does much of it for you), keep nearby trees trimmed, glance at your generation figures regularly, inspect the system every 1–2 years and book a professional service every 3–5 years. Expect to replace the inverter after about 10–15 years, while the panels themselves should last 25 years or more.
This guide covers the jobs that matter, what quietly cuts your output, and how to spot a fault early. Everything you are asked to do yourself is done from the ground. Roofs, wiring and inverter repairs are for trained people, and we will explain why.
Do solar panels need maintenance?
Yes, but not much. A rooftop array has no moving parts, no fuel and no engine to service, so it asks for far less attention than a boiler or a car. The Energy Saving Trust (EST) says solar systems “don’t need much maintenance”, but that regular upkeep keeps them efficient for their full lifespan of up to 30 years.
So why bother at all? Because several ordinary things quietly steal electricity without any warning:
- Dirt and dust reduce the sunlight that reaches the cells.
- Shade from a growing tree, a new chimney or a neighbour’s extension cuts output.
- Bird droppings and nests block light and leave debris near cables.
- An ageing inverter is the part most likely to fail, and a failed one means no electricity at all.
There are other good reasons to keep an eye on things. Some installers require a service within a set period to keep the warranty valid. A typical home system could also save around one tonne of carbon a year, and that saving only happens if the panels are actually working.
How solar panels work: a quick recap
To look after a panel, it helps to know what it is doing. Solar panels are made of cells, which are layers of semiconducting material, most commonly silicon. When light lands on a cell, it makes a direct current (DC) of electricity. The inverter then converts that DC into alternating current (AC), the kind your appliances and the grid use.
Two points matter for maintenance. First, cells work from light, not just from direct sun, so panels still make electricity on cloudy days, though the stronger the sunshine, the more they produce. Second, anything that blocks light before it reaches the cells, whether dust, leaves or a shadow, lowers the output.
That is all you need for this guide. If you want the full physics of how light frees electrons inside a cell, read our separate explanation of how solar panels work.
What’s in a home solar PV system (and what can go wrong)
When people say “solar panels”, they usually mean a whole system. Knowing the parts helps you describe a problem clearly to an installer, and it shows you which parts are safe to look at and which are strictly hands-off.
- The panels. Each has a glass front, a frame and the cells inside. Bypass diodes in the junction box let current skip a shaded or damaged group of cells.
- Mounting rails and fixings. These hold the array to the roof. A professional checks them for wear.
- DC cables and connectors. They carry electricity from the panels to the inverter. Never touch them.
- Isolator switches. There are DC and AC isolators, which let the system be switched off safely.
- The inverter. It converts DC to AC and is the part that most often goes wrong.
- The generation meter or monitoring app. This shows how much electricity the system has made.
- Extras. Some systems add optimisers, which stop one shaded panel dragging down the others, or a battery.
The average UK home system is about 4.5 kWp, which is around 12 panels covering 20–30 m² of roof. The “kWp” figure is the maximum power the system can produce in ideal conditions. If you want more detail on the technology and its uses, our guide to solar energy and solar panels goes further.
The rest of this article follows the order you will need it in: how to clean panels safely, what affects performance, how to check everything is working, and how long each part should last.
How to clean solar panels safely
Cleaning is the most visible part of solar panel maintenance, and also the part where people most often take risks they do not need to. The good news is that, in the UK, nature does a lot of the work for you.
How often should solar panels be cleaned?
The EST recommends cleaning roughly every 12–18 months. Clean more often if your panels are exposed to dust, overhanging trees or lots of bird droppings, and less often if you live somewhere rainy. In the UK, rain will clean panels tilted at 15° or more, which covers most pitched roofs. Debris tends to build up more on ground-mounted panels and in dusty areas, so garden arrays may need a wash more often.
Signs that your panels need cleaning include:
- a visible film of dirt, pollen or green growth;
- bird droppings that rain has not shifted;
- lower output on sunny days compared with the same month last year.
Dust and dirt reduce the sunlight reaching the cells, so a heavily soiled panel makes less electricity than a clean one beside it.
Step-by-step: cleaning from the ground
This method suits low or ground-mounted panels that you can reach safely while standing on even ground. If you have to stretch or strain, stop and hire a professional instead. Tick off each step as you go; your ticks are saved in your browser.
- Choose cool, dull weather, such as early morning or evening. Water evaporates fast off hot panels and leaves streaks and residue.
- Switch the system off first, following your installer’s manual.
- Look over the panels and cables from the ground. If you see damaged cabling, stop and tell your installer, because it can cause an electric shock.
- Rinse the panels with a gentle hosepipe spray that reaches them from where you are standing.
- For stubborn dirt or droppings, use a soft, long-handled brush with a little biodegradable soap.
- Rinse again with clean water so no soap is left behind.
- Draw a soft solar-panel wiper across the glass to remove any trails.
- Switch the system back on and check that the inverter shows normal operation.
What not to use
Some popular cleaning ideas do more harm than good:
- A pressure washer. It can interfere with seals and wiring and lead to water damage. A soft hosepipe spray is enough.
- Washing-up liquid. It can leave a film that helps dust stick, so the panels get dirty again faster.
- Harsh chemicals. These can affect the coatings on the glass.
- Cleaning in hot sun. The water dries too quickly and leaves marks.
Never climb on the roof
The safest way to clean roof panels is not to go near them. Falls from height were the most common cause of worker deaths in Great Britain in 2025/26, according to provisional HSE figures: 31 of 126 deaths, about a quarter. These figures cover all workers, and falls from height are a serious risk even for people trained and equipped for the job, so a keen homeowner with a ladder is not safer.
Never stand on solar panels either. They are not designed to bear a person’s weight, so they can crack or break. If the panels are on the roof and you cannot clean them from the ground, book a professional.
DIY or professional cleaning?
Professional cleaning typically costs between £20 and £200, depending on the size of the system, how hard it is to reach and how dirty the panels are. Choose an insured, reputable firm, and ask your installer if they offer a service or can recommend someone.
| Situation | Do it yourself | Call a professional |
|---|---|---|
| Ground-mounted or garden panels you can reach from level ground | Yes, using the steps above | Only if heavily soiled |
| Roof panels you cannot reach from the ground | No | Yes |
| Two-storey or steep roof | No | Yes |
| Stubborn droppings, moss or lichen | Gentle brush if reachable | If it will not come off |
| Damaged cable, cracked glass or loose fixings | No: stop and report it | Yes, via your installer |
| Birds nesting under the panels | No | Yes, once nests are no longer in use |
Small solar installations are the easiest to look after. If you have panels on a garden shed, a summerhouse or a garden light, you may be able to wash them from the ground, as long as you can reach them safely from level ground without stretching. Our guide to uses of solar energy shows how many different places solar cells now turn up.
What affects solar panel performance?
A panel’s label gives its power under test conditions, not under a typical British sky. Many things pull the real figure up or down, and understanding them tells you which problems you can fix and which you simply have to live with.
- Sunlight intensity. The stronger the sunshine, the more electricity the panels make. On cloudy days they still work, just at a lower level.
- Orientation. An unshaded south-facing roof is ideal. East- or west-facing roofs produce about 15–20% less energy than due south, and the EST does not recommend north-facing roofs.
- Tilt. Roughly 30–40° suits most pitched roofs in the UK, and panels tilted at 15° or more are cleaned by rain.
- Temperature. Hotter panels are less efficient, as explained below.
- Shading and dirt. Buildings, trees, chimneys, droppings and dust all reduce the light reaching the cells.
Why heat lowers output
It sounds odd, but a scorching day is not the best day for solar power. Panel ratings use Standard Test Conditions: 1,000 W/m² of sunlight and a cell temperature of 25 °C. Real cells run much hotter than the surrounding air when the sun is out.
For crystalline silicon panels, the power falls by about 0.3% per °C above 25 °C for newer panels, and up to about 0.5% per °C for older ones. Take a cell at 45 °C with a coefficient of −0.4% per °C. It is 20 °C over the reference, so its power is 20 × 0.4 = 8% below its rating. This is an illustrative sum, not a measurement of a particular panel.
So a cool, bright spring day can give excellent output for each hour of sun, even though summer has more hours of daylight overall.
Why a little shade causes a big drop: hot spots and bypass diodes
The cells in a panel are wired in series, like bulbs in an old string of fairy lights. The same current has to flow through every cell, so the weakest one limits the rest. A shaded, cracked or dirty cell makes less current than its neighbours.
That cell can be forced into reverse bias, which means it stops generating and starts turning energy into heat. The result is a hot spot. Persistent shading, heavy soiling and tiny cracks all raise the risk.
Panels have a defence. Bypass diodes, fitted one per group of cells rather than one per cell, let current skip a shaded or damaged group. Output drops, but the whole panel is not lost. Professionals can find hot spots with thermal (infrared) cameras, which is another reason a regular professional service is worthwhile.
At roof level, optimisers do a similar job. They stop one shaded panel dragging down the others and add per-panel monitoring. They bring little benefit if there is no shade.
Birds, leaves and snow
Bird droppings and pigeons
A single bird dropping acts as a small, concentrated patch of shade, and rain does not always remove it. Warm panels also make an appealing perch, and pigeons sometimes nest underneath them. Nest material and droppings then build up near cables.
The law matters here. Under the Wildlife and Countryside Act 1981, and subject to exceptions, it is an offence to intentionally take, damage or destroy the nest of any wild bird while it is in use or being built. Do not clear a nest yourself, and certainly not from a roof. Ask a professional to fit mesh or other bird-proofing around the panel edges once nests are no longer active.
You can also give birds somewhere better to go. Our guide to creating a bird-friendly home has ideas for welcoming wild birds to better spots than your roof.
Trees and leaves
The EST describes keeping nearby trees trimmed to minimise shading as the main maintenance job for most owners. A sapling that was harmless when the panels went up can shade them within a few years. Leaves and moss can also collect on panels with a low tilt.
Snow
Panels make little electricity while they are covered in snow, but there is no need to rush to clear it. Smooth, tilted glass warms up as soon as light gets through, and snow usually slides off by itself. Do not climb up to sweep it away, and do not use hot water or tools on the glass. Wait for it to melt and slide.
How to check your solar panels are working
Most faults announce themselves if you know where to look. A few minutes each week is enough.
- Read the generation meter. Many meters show a flashing light while the system is generating, but the signals vary, so check your meter’s manual or your handover pack.
- Look at the inverter. The screen shows the power being made now in watts or kilowatts. Inverters shut down at night, so a blank screen in the dark is normal. A fault shows as a fault code, so note it down.
- Check the monitoring app or emails. Some inverters have online monitoring and can email you if the system fails.
- Check the solar breaker. Make sure the solar breaker in your consumer unit is switched on.
- Call your installer. If there is still no output, give them the fault code and the date it started.
Keep a regular record of the meter reading, such as once a week. If the reading has not changed over a week, check the inverter for a fault code and tell your installer.
How common are faults? A Which? survey of 2,039 solar panel owners in April 2024 found that nearly seven in 10 had had no problems. The most common and most serious problem was the inverter.
Your panels made 30% less electricity in July than last July, though both months were equally sunny. Give two possible causes. (2 marks)
Any two of: shading from tree growth or a new building; dirt or bird droppings on the glass; an inverter fault; a damaged panel or hot spot.
How long do solar panels last?
Solar panels should last 25 years or more, according to the EST, and the same organisation says that with good upkeep a system can keep working for up to 30 years. They do not suddenly stop at the end of that time. Instead, they slowly make a little less electricity each year.
This slow decline is called degradation. The US National Renewable Energy Laboratory (NREL) reviewed nearly 2,000 measured rates and found a median of 0.5% per year. A later study led by Sandia National Laboratories (with NREL and the University of Central Florida) of 834 newer modules over five years found a mean of 0.62% and a median of 0.58% per year, and it noted that the decline is not perfectly even from year to year.
Try the sum yourself. A system making 3,000 kWh in its first year, losing 0.5% each year, makes about 3,000 × 0.99525 ≈ 2,647 kWh in year 25. That is roughly 88% of the original. Change the numbers below to see what faster or slower ageing means for your own system.
Many manufacturers’ performance warranties guarantee roughly 80–90% of original output after about 25 years. Check your own warranty document for the exact figure. For a wider look at what solar power does well and badly, see our pros and cons of solar energy.
When to replace the solar inverter
Panels have no moving parts, but the inverter works hard every daylight hour, converting DC to AC. It is the part most likely to give trouble. In the Which? survey, the inverter was the most common and most serious problem owners reported.
Inverters typically need replacing every 10–15 years, usually at a cost of around £800. Most come with a warranty of at least five years, often extendable to up to 15 years. A 15-year warranty may cost almost as much as a replacement inverter, so work out which option suits you before you buy.
Signs that your inverter may be failing include:
- a fault code or warning light on the inverter;
- a blank screen during the day;
- zero output on a bright, sunny day.
Replacing one is a job for a professional. Which? advises contacting your installer for professional advice on replacement. An inverter has no user-serviceable parts, so never open it. Unlike a spinning machine, such as the ones in our guide to how generators work, the panels themselves have nothing to wear out mechanically, which is why the electronics tend to fail first.
UK checklist: MCS, warranties and the Smart Export Guarantee
A little paperwork protects your investment as much as a clean panel does.
- Use an MCS-certified installer. The EST suggests getting quotes from at least three. Your installer should test the system and talk you through how it works.
- Keep your documents. That means the MCS certificate and the warranty paperwork. Many parts are covered by installer warranties.
- Registration. Systems must be registered with the distribution network operator (DNO), and the installer usually does this.
- Servicing rules. Some installers require a service within a set period to keep the warranty valid.
The Smart Export Guarantee (SEG) began on 1 January 2020. Larger licensed energy suppliers must offer to pay owners of small-scale generators, including solar PV, for the low-carbon electricity they export to the grid. It applies in Great Britain only. Tariff rates must always be above zero, and you can apply to any SEG licensee, not just your current supplier. Suppliers generally ask for an MCS certificate and an export-capable smart meter.
The EST says the SEG typically pays around 12p per unit, while buying a unit costs more than twice that. So electricity you use yourself is usually worth more than electricity you export. Maintenance therefore protects the output you rely on most. For a realistic view of what solar power can and cannot deliver, read renewable energy: expectations vs reality.
Solar panel maintenance schedule
This table pulls the advice together. Use it as a yearly reminder.
| When | Job | Who |
|---|---|---|
| After big storms, or any time | Look at the panels and cables from the ground | You |
| Weekly or monthly | Note the meter or app reading and check for fault codes | You |
| Every 12–18 months | Clean the panels | You from the ground, or a professional |
| Every 1–2 years | Inspect for wear and tear, wiring issues and water damage | You visually, or a professional |
| Every 3–5 years | Full service for small cracks or inverter issues | MCS-certified installer or professional |
| About 10–15 years | Replace the inverter | Professional |
| 25+ years | Plan for panel replacement and recycling | Professional |
What happens to old solar panels?
Solar panels are Category 14 equipment under the WEEE Regulations 2013. Producers finance the collection and recycling. Do not put old panels in general waste. Ask your installer, or use an approved collection route.
Test yourself and revise
Frequently asked questions about solar panel maintenance
Do solar panels need maintenance?
Yes, but only a little. Panels have no moving parts, so the Energy Saving Trust says they don’t need much upkeep. A clean every 12–18 months, a visual check every 1–2 years and a professional service every 3–5 years keep a system efficient for its full lifespan.
How often should solar panels be cleaned in the UK?
About every 12–18 months, according to the Energy Saving Trust. Clean more often if the panels sit under trees, in dusty areas or where birds gather, and less often in rainy areas. Rain cleans panels tilted at 15° or more, so roof panels usually need less attention than ground-mounted ones.
Can I clean my solar panels myself?
Only if you can do it safely from the ground. Use a gentle hosepipe spray and a soft, long-handled brush, and switch the system off first. If the panels are on a roof you cannot reach from level ground, or you have to strain, hire a professional. Never climb on the roof.
Can you use a pressure washer or washing-up liquid on solar panels?
No. A pressure washer can interfere with seals and wiring and cause water damage. Washing-up liquid can leave a film that helps dust stick. Use a soft hosepipe spray, and a little biodegradable soap with a soft brush if needed. Harsh chemicals can also affect coatings.
How much does solar panel maintenance cost in the UK?
Professional cleaning typically costs £20–£200, depending on the size of the system, access and how dirty the panels are. Cleaning yourself costs very little. The main larger cost is replacing the inverter after about 10–15 years, which usually costs around £800.
How do I know if my solar panels are working properly?
Check the generation meter and the inverter screen for power readings and fault codes. Note the readings weekly and compare them with the same month last year. If output is zero in good light, check the breaker and call your installer.
How long do solar panels and inverters last?
The Energy Saving Trust says panels should last 25 years or more, losing about 0.5% of output a year on average according to NREL research. Inverters typically need replacing every 10–15 years. Most inverter warranties last at least five years and can often be extended to up to 15 years.
Should I remove snow from solar panels?
No. Snow usually slides off smooth, tilted panels as they warm up, and the risks of climbing up or using tools or hot water are not worth a few hours of extra output. Wait for it to melt and slide. If the system seems faulty afterwards, call a professional.
How do I stop pigeons nesting under my solar panels?
Ask a professional to fit mesh or bird-proofing around the panel edges, once any nests are no longer in use. It is an offence, with exceptions, to intentionally damage or destroy a wild bird’s nest while it is in use or being built, so do not remove nests yourself.
