Solar panel maintenance guide (UK)

The truth about cleaning

UK rainfall is enough to keep most panels operating above 95% of theoretical output. Cleaning provides a measurable benefit only on near-flat roofs (under 15° pitch), in dusty rural areas, near major roads or close to coastal salt spray. When you do clean, use deionised water and a soft brush — never a pressure washer.

Inverter lifetime

String inverters typically need replacement at 12–15 years (£700–£1,400). Hybrid inverters work harder and often last 10–12 years (£900–£1,800). Budget for one replacement during the 25-year panel life.

Degradation

Modern N-type panels degrade at around 0.35–0.4% per year, retaining 85–88% of original output at year 25. Budget assumptions of 0.5%/year remain conservative.

Battery lifetime

LFP (lithium iron phosphate) batteries from GivEnergy, Tesla, BYD and others are warrantied for 10–15 years and 6,000–10,000 full cycles. Expect 70–80% of original capacity at end of warranty.

Annual checklist

• Check generation vs prior year via the inverter app
• Visual inspection of DC isolator and cabling from ground
• Trim any vegetation now shading the array (especially neighbouring trees)
• Review SEG payments and switch tariffs if a better rate is available

Insurance

Most UK home insurers cover solar PV under buildings cover, sometimes requiring a phone notification post-install. Confirm with your insurer; never assume.