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 (and what NOT to do)
The Energy Saving Trust's guidance is clear on the do's and don'ts:
- Do use a soft brush, a hosepipe with a gentle spray, and biodegradable soap.
- Do clean from the ground where possible, using a long-handled brush.
- Do clean in cool weather — hot panels evaporate water fast, leaving streaks.
- Do turn off the system first.
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.
Sources: Energy Saving Trust (solar panel cleaning & maintenance, August 2026), MCS guidance, GOV.UK. Figures verified August 2026. 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.