Shading

Shading is perhaps the biggest problem for solar PV systems, and a poorly designed system can lose a huge amount of performance due to a relatively small amount of shading.

A basic solar PV system, run in series, will operate at roughly the same power output as the most shaded PV cell or string of PV cells in the entire array. Essentially this is because a shaded cell will act as  an electric radiator, absorbing excess electricity from the other panels and emitting it as heat, so not only will a poorly designed system lose a huge amount of performance from a small amount of shading, but it's also likely to reduce the life of the shaded panels.

To get around this problem all Leeds Solar's PV panels organise their PV cells into strings of cells, and have bypass diodes between the strings of cells that automatically bypass a shaded string of cells. When bypassed, a shaded cell will only take one string of cells out of production, and not affect the rest of the panel or arrays output.

The more strings of cells that are affected by shading, the greater the impact on the overall systems output. 

Some SMA inverters have a special function to allow them to cope much better in shaded situations, known as Optitrack Global Peak. This function is available on the 4000TL and 36000TL inverters as standard, and we can now add this function to the HF inverters and Sunny Tri-power inverters if required. This function needs to be specifically set up by the installer during the commisioning process.