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Solar · Maintenance

How often do solar panels need cleaning in the UK?

Short answer

Most UK roof panels tilted at 15 degrees or more are largely kept clean by rain. The Energy Saving Trust suggests a clean every 12 to 18 months, sooner if trees, birds, dust or a shallow tilt leave visible dirt. Clean when the monitoring shows a drop or you can see grime, not on a fixed calendar.

Last checked 24 September 2026 · 2 sources

In more detail

  • EST main solar page (updated 27 Aug 2026): in the UK rain cleans panels tilted at 15 degrees or more; ground-mounted arrays and dusty areas may need occasional cleaning.
  • EST cleaning blog (7 Jan 2026): clean every 12-18 months; more often near trees, birds or dust; inspect every 1-2 years; full professional service every 3-5 years.
  • Shallow-tilt, flat-roof and ground-mount arrays, and arrays near farms, roads, coast or under trees, soil faster; bird droppings do not wash off with rain and can shade whole cells.
  • Check the frame's bottom edge: a line of dirt/moss along the lower edge is common on low-tilt landscape panels and can shade the bottom row of cells.
  • Use the monitoring: compare the same sunny month year on year; a gradual gap that disappears after heavy rain suggests soiling.

The facts, dated

  1. 01
    Rain cleans UK roof panels tilted at 15 degrees or more (EST) — 15 degrees tilt

    installer_view · UK · checked 24 September 2026 · Energy Saving Trust

  2. 02
    EST recommends cleaning every 12-18 months — 12-18 months

    installer_view · UK · checked 24 September 2026 · Energy Saving Trust

  3. 03
    Professional cleaning typically costs GBP 20-200 (EST citing Heatable) — 20-200 GBP

    market_data · UK · checked 24 September 2026 · Energy Saving Trust

What we saw in the field

[QA review 2026-09-24] I-1 CONTRADICTS: installer 'clean about every six months, no other routine domestic maintenance'. EST cleaning page (checked 2026-09-24): check panels every 12-18 months and give a light clean every 12-24 months, more often for ground-mounted arrays or homes near busy roads/farmland; EST also advises inspection and a professional service. MIS 3002 Appendix F lists intermediate (10 yr) and full (15 yr) inspections. Six-monthly cleaning is defensible only for ground-mount, low-tilt, dusty or bird-affected arrays.

Sources

Last checked: 24 September 2026