Capacity and SAP

[gazz27]

New to this forum and find it very informative
Just so you know I am an end user not an installer.
I was just wondering when you have an installation, is the declared capacity for FITS just the output of the panels
or is it related to the SAP calculations. I have some shading in the morning which will put my output down by about 10-15%.
This is confirm by British Gas when I give them my FIT reading and they tell me I am about 15% under what they would expect.

Any thoughts.

Thanks Gary

 

[TedM]

The Declared Net Capacity and Total Installed Capacity of your PV system is calculated based purely on the rating of the panels and inverter that have actually been installed. Other factors that might affect your output, such as latitude, roof angle, direction or shading are ignored for this. The FiTs band you fall in, and hence the rate you get paid, is based on the Total Installed Capacity figure for your system.

SAP is just a rough tool to predict how much electricity a generic system of a certain size is likely to generate in a year and does take roof angle and shading into account, but is not precise.