Site III.3

February 2018
Nominal Capacity
51.2 kWp
Yield since COD
1052 kWh/kWp
Possible Gain
5% to 10%
1.9 ₹/Wp, 0.5 ₹/Wp/a


The PV plant shows inhomogeneous amount of soiling. There is evidence of both partially open and connectors with abnormal temperatures. Furthermore, the installed modules are hotspot sensitive. It is recommended to (i) increase the cleaning frequency with an appropriate cleaning method, (ii) install an irradiation sensor (iii) continuous cleaning of the inverter-fan filters, (iv) replacement of warm module connectors and (v) yearly thermography inspection of the modules. The estimated production boost expected by the retrofitting actions lies between 5 -10%.

Image gallery

Main Findings

The thermography (IR) inspection revealed MC4 connectors with abnormal temperatures.
The inverter fan filters (outlets) are partially blocked, leading to a higher risk of inverter shut down.
Since there is no weather station installed on-site, the performance ratio is not monitored.
A small amount of connectors were not tightly closed.
Module cables are in contact with sharp edges and bolts from the mounting structure.
Global irradiation on collector plane can be improved (1%), and near shading losses reduced (-1.6%), at the optimal angle of 10°. However, cleaning cycles might need to be improved.
The modules are hotspot sensitive. This defect could compromise the long-term reliability of the modules.
Electroluminescence imaging did not reveal significant or severe cracks in the selected module sample.
The device used for cleaning the modules (mop), does not achieve a homogenous cleaning.

Impact on Performance

Near Shading

Based on the interrow spacing, the simulation estimates near shading losses of ca. 3% on system level.

Estimated Loss
≈ 3%

Soiling measurements were conducted via short circuit current reduction and nominal power before and after cleaning. The estimated soiling loss averages 3%.

Estimated Loss
≈ 3%
Total Estimated Energy Loss
≈ 6%

Proposed Solutions

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.
Manual cleaning cycles shall be increased based on the results of a soiling study that adjusts the cleaning needs to each season.
Thermography (IR) inspection shall be performed to find out the amount of connectors with abnormal temperatures, followed by their suitable replacement.
Thermography (IR) inspection of the modules shall be performed annually to monitor the evolution of the warm cells and hotspots.
The outlets of the inverter fan shall be continuously clean (part of the O&M) to avoid inverter overheating.