The PV plant shows high levels of soiling caused by bird droppings and a significant amount of inactive cells strings partially induced by soiling. During the assessment installation failures of the DC cabling were detected as well module damages and near shading. It is recommended to (i) change the module tilt to 15°, (ii) increase the cleaning frequency to three times per month, (iii) increase the albedo using white gravel, (iv) relocate the shading objects and (v) replace modules with performance drops beyond manufacturer ́s guarantees. The estimated production boost caused by the retrofitting actions lies between 14% and 18%.
Soiling measurements were conducted measuring both the short circuit current and nominal power before and after cleaning at irradiations higher than 800W/m2. The estimated soiling factor is in the range of 8 – 9%.
Modules with inactive cell strings underperform 33% to 66% depending on the amount of affected strings. The extrapolation of the inspected sample to the whole system leads to a loss of 5% on system level.
Total Estimated Energy Loss
The cleaning cycles shall be increased and defined based on a soiling study that adjusts the cleaning needs to each season.
Spikes against birds shall be installed at the upper edge of the modules.