Effect of Shade on Solar Panels Output

What is the Effect of Shade on Solar Panels Output?

When installing solar panels it is important to choose a location that has minimum shading as electricity generated by solar panels drops when any one panel or part of a panel is shaded. Until today I'd not realised quite how much difference it makes.

Our solar panels are on our main roof which also has a velux window fitted. This is very convenient for checking the condition of the panels and for stopping pigeons nesting under them. It also has the potential for creating shade on the panels when the window is open!


What is the Effect of Shade on Solar Panels Output?

When checking the solar panel output logs in Sunny Explorer I noticed that there was a sharp drop in output from the panels despite it being a totally sunny day. On further investigation I realised that the velux window had been opened due to the heat and that as the sun dropped in the sky it was creating a shadow across the 2 panels.

Despite the shading only covering a tiny fraction of 2 panels over the course of about 90 mins at the end of the day we lost around 1kWh of solar electricity generation. Imagine how much could be lost by more significant shading over a longer period of time.