Solar Panel Output Dropping
Solar panels producing noticeably less electricity than in previous years or compared to expected levels.
What Is Causing This?
- 1Panels dirty or covered in bird droppings, lichen, or moss
- 2Partial shading from a growing tree
- 3Panel degradation over many years
How Urgent Is This?
This is a cosmetic issue. It is not causing damage and can be addressed in your own time.
What Needs to Be Done
A solar installer will clean the panels, check for shading issues, and test individual panel and string output. They may identify a faulty panel or optimiser to replace.
How Much Will It Cost?
National average estimate
Labour: £627 – £1,500 | Materials: £1,833 – £5,010
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Ask a QuestionPlanning Permission Guidance
Some fixes for this problem may require planning permission or building regulations approval. Check if your project needs permission:
How to Prevent This
Have panels cleaned every 1 to 2 years. Trim trees that may grow to shade the panels. Monitor generation output to spot drops early.
Related Problems
The solar panel system showing zero or very low generation despite sunny conditions.
Visible crack or damage to the glass surface of a solar panel, which may reduce output.
Pigeons or other birds building nests under the gap between solar panels and the roof.
Other Solar Panel Installer Problems
The solar panel system showing zero or very low generation despite sunny conditions.
Pigeons or other birds building nests under the gap between solar panels and the roof.
Visible crack or damage to the glass surface of a solar panel, which may reduce output.
The solar inverter displaying an error code, red light, or not operating, stopping power generation.