The PV plant is likely affected by an early stage of PID. Electroluminescence imaging did not reveal significant mechanical damages. Hotspots induced by heavy soiling were discovered though IR inspection. Regarding safety requirements, the mounting structure hangs beyond the roof edge (it shall considers DIN 1055). It is recommended to (i) clean all the modules including those with difficult access, (ii) validation that all strings and module connectors are closed (iii) implement anti-PID measures. The estimated production boost expected by the retrofitting actions lies between 10% and 15%.
No weather station has been installed and the Performance Ratio is not tracked.
Soiling measurements were conducted before and after cleaning. The estimated soiling loss is on average 3.5%. However, the measured modules were much cleaner than modules that are more difficult to access.
Total Estimated Energy Loss
The design should be checked for static stability.
A weather station, or at least an irradiation sensor on the module plane, shall be installed so that the performance of the system can be properly determined.
All strings should be checked for closed module plugs since the measured power loss in the examined subsystem was 37%.
The modules should be cleaned regularly.
The loose hanging cables should be fixed and the bending radii checked.
An anti-PID measure, such as anti-PID box, shall be implemented in order to stop or reverse the degradation.