BrightGridShading is one of the most important factors to assess before installing solar panels. Trees, chimneys, dormers, neighbouring buildings and roof structures can reduce generation. The solution is not always to reject the roof; careful system design can sometimes reduce the impact.
Common causes of solar shading
- Trees
- Chimneys
- Dormer windows
- Nearby buildings
- Roof structures
- Satellite equipment
- Other roof sections
Why does shading matter?
Solar panels generate electricity from sunlight. When part of an array receives significantly less sunlight, the electrical behaviour of the affected panels and the wider string can change depending on the system architecture.
How can an installer deal with shading?
- Change the panel layout.
- Use different roof faces.
- Use suitable module-level power electronics.
- Configure strings carefully.
- Avoid heavily shaded roof areas.
- Model seasonal shading rather than only looking at one moment.
| Shading source | What should be assessed |
|---|---|
| Tree | Height, growth and seasonal shadow movement |
| Chimney | Shadow position and roof layout |
| Neighbouring building | Distance, height and sun path |
| Dormer | Available panel layout and local shading |
Do not only assess today's shading
Trees can grow substantially over the life of a solar installation. A roof that is relatively clear today may experience more shading in future, so the expected long-term environment should be considered.
A shading assessment should be part of the design
The installer should explain how shading has been considered and how it affects the expected annual generation.
Check your roof for solar shading
Assess roof orientation, shading and panel layout before committing to an installation.
Explore SolarFrequently asked questions
Can I install solar panels if I have trees?
Potentially. The effect depends on tree height, location, seasonal shading and the roof layout.
Does chimney shading affect solar panels?
It can. A professional design should model the chimney's effect and position panels accordingly.
Can optimisers help with shading?
Suitable module-level electronics can sometimes reduce the effect of uneven panel conditions, but they do not create sunlight where there is none.
Should I cut down trees before installing solar?
Not automatically. The shading should first be assessed and alternatives considered.
Sarah Kimani
Systems Designer at BrightGrid Energy
