The honest answer first
Solar panels are essentially zero-maintenance. They have no moving parts, the rain does most of the cleaning on a pitched roof, and the panels themselves last 25–30+ years.
Over a 25-year system life, a typical UK household will:
- Clean the panels two or three times (or more if under trees or near farmland)
- Replace one inverter (around year 12)
- Do a few professional checks
Total lifetime maintenance: typically £1,200–£2,000 on a 4 kWp system — a small fraction of the £12,000+ it saves over the same period. That's the whole point of solar: it keeps generating, almost for free.
Cleaning: how often & how much
The Energy Saving Trust recommends cleaning every 12–18 months. But UK rainfall does a lot of the work — on a pitched roof, rain washes most dust away. You only really need to clean more often if:
- You live near trees (leaves and bird droppings)
- You're near farmland or a busy A-road (dust and pollen)
- You have a flat roof (no natural rain run-off angle)
Cleaning costs:
| Method | Cost |
|---|---|
| DIY (hose + soft brush) | ~£0 |
| Professional clean (whole system) | £20–£200 |
| Professional clean (per panel) | £4–£15 |
Bird droppings cause more output loss than dust, so a localised wash with a soft brush and deionised water is usually enough when they appear.
How to clean solar panels (step by step)
- Turn the system off before cleaning.
- Use a soft brush and a hosepipe with a gentle spray — not a pressure washer.
- Clean from the ground where possible, using a long-handled brush.
- Clean in cool weather — hot panels evaporate water fast, leaving streaks.
- Use biodegradable soap (avoid washing-up liquid).
Never stand on the panels — they aren't built for that weight and can crack. Never use a pressure washer — it can damage seals and wiring, causing water ingress. Avoid washing-up liquid — it leaves a film that attracts dust.
Inverter: the one real cost
The inverter is the one component that doesn't last 25 years. It converts your panels' DC electricity into usable AC, and it works hard doing so.
| Item | Lifespan | Replacement cost |
|---|---|---|
| String inverter | 10–15 years | £500–£1,500 (typically ~£800) |
| Microinverters / optimisers | 25 years (warrantied) | Rarely need replacing |
Budget for one inverter replacement over the system's life. This is the single largest maintenance cost, so it's worth factoring into your long-term sums — our ROI calculator accounts for it.
The maintenance checklist
This is the Energy Saving Trust's official maintenance schedule:
| Interval | Task |
|---|---|
| Every 12–18 months | Clean the panels (dust, dirt, bird droppings) |
| Every 1–2 years | Inspect panels (or have a professional do it) — check wear, wiring, water damage |
| Every 3–5 years | Full professional service — check for small cracks and inverter issues |
Some installers require a professional service within a specific period to keep the warranty valid. Keep your warranty documents safe and check the terms.
DIY vs professional
| Task | DIY or professional? |
|---|---|
| Monitoring generation (app/display) | DIY ✅ |
| Cleaning from the ground (hose + brush) | DIY ✅ (low pitch only) |
| Roof-level cleaning | Professional (working at height) |
| Electrical testing & repairs | Professional (Part P certified) |
| Inverter error-code checking | DIY (consult the manual) |
When output drops: what to check
Check your monitoring app monthly. An unexplained 10%+ drop in generation usually points to one of these:
- Dirt and debris — a clean can recover several percent quickly
- Shading changes — trees grow, new buildings appear
- Inverter fault — inverters fail gradually, especially near end of life
- Wiring faults — a loose connection or corroded junction box
If the cause isn't obvious, book a professional check. If it's within warranty, the manufacturer covers qualifying repairs.
Lifetime maintenance cost
| Item | Frequency | Total over 25 years |
|---|---|---|
| Professional cleaning | Every 2–5 years | £200–£600 |
| Inverter replacement | Once (~year 12) | £500–£1,500 |
| Inspections / minor repairs | As needed | £300–£800 |
| Total | — | £1,200–£2,000 |
Spread over 25 years, that's roughly £50–£80 a year — against £500–£1,000+ in annual savings. Solar's maintenance story is one of the strongest reasons it's such a good long-term investment.
See your full savings picture
Maintenance is a rounding error next to solar's lifetime savings. Calculate yours — including the inverter replacement.
Calculate my ROI →FAQ
Do solar panels need servicing every year?
Not strictly. The Energy Saving Trust recommends an inspection every 1–2 years and a full professional service every 3–5 years. Annual checks are only essential once your inverter is over 10 years old.
Is solar panel servicing mandatory in the UK?
No, it's not a legal requirement. But regular maintenance protects output and keeps manufacturer warranties valid.
Will rain clean my solar panels?
Mostly, yes — on a pitched roof, rain removes the bulk of dust. You mainly need manual cleaning for bird droppings, or if you live in a dry, dusty area.
Does cleaning solar panels make a big difference?
Soiling can reduce output by 5–15%, and bird droppings more. On a heavily soiled system a clean can recover several percent of output — but for most UK homes the rain keeps panels clean enough that yearly cleaning is optional.
How often should I clean my solar panels in the UK?
Every 12-18 months, according to the Energy Saving Trust. In rainy areas you can clean less often; in drier, dustier locations or under trees, clean more frequently. UK rain does a good job of keeping pitched roof panels clean on its own.
How much does solar panel cleaning cost in the UK?
Professional cleaning typically costs £20 to £200 for a whole system, depending on size, accessibility and how dirty the panels are. DIY cleaning with water and a soft brush costs almost nothing.
How long do solar inverters last?
Solar inverters typically need replacing every 10-15 years, at a cost of around £800 for a typical system. This is the one significant lifetime cost — panels themselves last 25-30+ years.
Can I use a pressure washer on solar panels?
No. The Energy Saving Trust advises against high-pressure washers because they can damage seals and wiring, leading to water damage. A soft spray from a garden hosepipe is enough.
Is solar panel maintenance expensive?
No. Solar panels are very low-maintenance. Most years cost little more than an optional £100-£200 inspection, and the only significant lifetime cost is one inverter replacement at £500-£1,500 after 10-15 years. Total lifetime maintenance is typically £1,200-£2,000 over 25 years.
Sources: Energy Saving Trust (solar panel cleaning & maintenance, August 2026), MCS guidance, GOV.UK. Costs vary by region, system size and accessibility.
Disclaimer: this guide is for general information only. Always follow your installer's and manufacturer's specific guidance, and use qualified professionals for any work at height or electrical repairs.