Site II.4

Health
COD
2017
Nominal Capacity
50.7 kWp
Yield since COD
524 kWh/kWp
Possible Gain
34% to 39%
CAPEX, OPEX
0.9 ₹/Wp, 0.8 ₹/Wp/a

Abstract

The PV plant shows design failures such as the disregard of the inter-row and near shadings. The modules show signs of soiling due to foliage, hard water and bird drops. Advanced module degradation caused by PID was detected. Some MC4 connectors are overheated due to an increase of the surface resistance. It is recommended to (i) increase the cleaning frequency, (ii) rearrange strings based on the shading categories, (iii) trim regularly the surrounding trees if allowed by the authorities, and (iv) implement anti-PID solutions. The estimated production boost expected by the retrofitting actions lies between 34% and 39%.

Image gallery

Main Findings

Many areas are heavily shaded by trees.
There is no weather station, and hence no PR monitoring.
Some connections were found to be loose leading to an increase of the contact resistance.
PID presence was detected via IR and EL inspections.

Impact on Performance

Potential Induced Degradation

PID loss was determined based on the on-site measurements to be as high as 56%. The degradation has already reached advanced stage.

Estimated Loss
≈ 56%
Soiling

Soiling losses were determined based on the measurements on site to be on average 0.5%.

Estimated Loss
≈ 0.5%
Near Shading

Based on the simulation, shading losses are estimated to be 15% at the system level.

Estimated Loss
≈ 15%
Total Estimated Energy Loss
≈ 71.5%

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 nearby trees shall be trimmed regularly. 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.
Anti-PID measures 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.