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Solar panel maintenance and poor output

Panels need little maintenance, but faults go unnoticed without monitoring. Check the inverter first; leave anything on the roof to a professional.

Updated 3 October 2026 · energy.org.uk editorial team

Is it really poor output?

Low output in winter or on dull days is normal. Before suspecting a fault, compare:

  • the same month in different years, or
  • a month against the estimate for your postcode in the solar panel calculator, or the installer's estimate.

A sudden drop to zero, or much lower output on a clear day, suggests a fault.

Common causes

  • The inverter has tripped or shows a fault. Check its display or app for error messages.
  • New shade, from trees growing or a new building.
  • Dirt, bird droppings or moss, especially on shallow roofs. Rain cleans most pitched roofs.
  • Damaged wiring, sometimes from birds or squirrels nesting under panels.
  • Monitoring has stopped, for example after a change of Wi-Fi router, so the system looks as if it isn't generating.

Check

What to check first

  • The inverter display or app, for faults and today's generation.
  • The isolator switches and consumer unit, to see if anything has tripped. Follow the installer's instructions; don't open any equipment.
  • Your generation meter or export readings, to confirm whether the system is really generating.

Do

Practical next steps

  1. Note the inverter's error code, if any.
  2. Contact your installer or the inverter manufacturer, quoting your warranty details.
  3. If the panels need cleaning or inspection, use a professional with suitable access equipment.
  4. Keep a monthly record of generation, so you notice problems early.

Take care

Important limitations

  • Never go on the roof yourself. Working at height is dangerous, and panels carry electricity whenever it is light.
  • Cleaning is not automatically worthwhile; it depends on the roof, the dirt and the cost of access.
  • Inverters usually have shorter warranties than panels and may need replacing during the system's life.

Related tools and guides

Sources

Official sources checked 3 October 2026.