Site IV.4

Site ID
Nominal Capacity
20 kWp
Average Specific Yield
781 kWh/kWp
Total Estimated Loss
Possible Gain
16% to 25%
1.7 ₹/Wp, 0.7 ₹/Wp/a
Expenditure / Energy


The Plant was installed facing East, reducing almost by a quarter the overall energy generation. It is significantly affected by near shadings and soiling. Additionally, various modules and installation defects were discovered through visual and infrared inspection. In general, module power performance is significantly lower than the expected values (due to PID effect). It is recommended to (i) replace modules with exposed J-box, (ii) increase cleaning frequency, (iii) re- install the irradiation sensor, (IV) implement an anti-PID box solution. The estimated production boost expected by the retrofitting actions lies between 16-25%.

Image gallery

Main Findings

The plant was installed facing East. If the system was designed to bring the maximum yield, the current azimuth (-90°) represents -10.7% loss towards the optimum irradiation on the plane.
The irradiation sensor is installed at the wrong tilt, and is significantly shaded and soiled.
Significant near shading effects are caused by the trees surrounding the system.
Various module product failures were discovered, such as busbar corrosion, defective J-boxes, hotspot sensitivity and broken glass.
A combination of installation failures were also present: backsheet scratches, open and loose connectors, mounting structures with sharp edges and corroded elements.
Although open J-boxes might not have an impact on the performance, for now, this is an important safety issue that should be addressed. Nearly 40% of the modules were missing the lid.
The access to the roof is difficult. This could have caused module damages during transportation, handling and installation, and possibly, performance losses.

Impact on Performance

Heavy Soiling
Soiling measurements were conducted measuring both the short circuit current and nominal power before and after cleaning. The estimated soiling loss is on average 2.9%.
Estimated Loss
≈ 2.9%
Potential Induced Degradation
PID, at initial stages, could be responsible for 15% of the losses on system level. The degradation is in on intermediate stage.
Estimated Loss
≈ 15%
Near Shading
The near shadings are responsible for an irradiation reduction on the tilted plane of approx. 4.9% at system level.
Estimated Loss
≈ 4.9%
Deviation from South
The deviation from true south results in a -3% loss at system level.
Estimated Loss
≈ 3%
Total Estimated Energy Loss
≈ 25.8%

Proposed Solutions

Considering safety and system long-term reliability, the module J-boxes shall be evaluated. Modules with exposed J- boxes (corrosion in the diodes) shall be immediately replaced.
Manual cleaning cycles shall be increased based on the results of a soiling study.
An anti-PID box shall be installed to stop module degradation.
PV modules showing power drops above the warranty conditions shall be replaced. If the replacement is not possible, the modules shall be regrouped according to power and defect classes, within the same string and assigned to individual MPPT (based on infrared inspection with high irradiation levels and after cleaning activities).
The irradiation sensor should be properly reinstalled, cleaned and calibrated to ensure accurate readings.