Site II.5

Health
COD
2017
Nominal Capacity
63.375 kWp
Yield since COD
375 kWh/kWp
Possible Gain
18% to 23%
CAPEX, OPEX
0.7 ₹/Wp, 1.2 ₹/Wp/a

Abstract

The PV plant shows moderate levels of soiling caused by bird drops and hard water. The system contains design failures such as the disregard of the near shadings and inaccurate DC cable sizing. The east part of the system is heavily shaded by trees. The degree of PID degradation is estimated to be at least 10%. It is recommended to (i) increase the cleaning frequency, (ii) trimming of trees surrounding the system if allowed by the authorities, (iii) rearrange the strings based on the shading situation if the latter is not possible and (iv) implement anti-PID measures. The estimated production boost expected by the retrofitting actions lies between 18% and 23%.

Image gallery

Main Findings

Many areas are heavily shaded by trees.
Soiling on the modules was noticed to be moderate during the visit. The system was cleaned two days earlier and it is cleaned every 15 days.
There is no weather station, and hence no PR monitoring.
PID presence was detected via IR inspection.
String cables are built with a diameter of 4mm2 which in increases the DC cable losses.
Occasionally string cables damaged by sharp edges have been detected.

Impact on Performance

Soiling

Soiling losses were determined based on the measurements on site to be 3% on average.

Estimated Loss
≈ 3%
Near Shading

Based on the simulation, near shading losses are estimated to be 6% at the system level.

Estimated Loss
≈ 6%
Potential Induced Degradation

PID loss was determined based on the on-site measurements and can be as high as 26% at the module level. The degradation has already reached advanced stage and reduces the system performance by at least 10%

Estimated Loss
≈ 10%
Total Estimated Energy Loss
≈ 19%

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.
The trees surrounding the system shall be trimmed if allowed. Otherwise, a restringing of the modules shall be conducted in the following way: modules with similar shading conditions shall be installed in the same string or at least assigned to one MPPT.
The cleaning cycles shall be increased based on the results of a soiling study that adjusts the cleaning needs to each season.
An anti-PID measure, such as anti-PID box, shall be implemented in order to stop or reverse the degradation. PV modules showing power drops above the warranty conditions shall be replaced. If the replacement is not possible, the modules shall be regrouped in power classes within the same string and assigned to individual MPPT.
Covering the ground with white gravel or white paint increases the albedo factor to 0.5, leading to performance boost of approximately 1%.