Defects in Indian Solar Power Plants

Solar PV installations have been growing at an unprecedented rate in India, with the cumulative capacity already being more than 20GW. However, this rapid scaling, coupled with ever falling tariffs and intense competition may be resulting in compromised quality. And therefore, while we may have installed the capacity, we may not be generating as much green power as we would have expected.

Over a period of 1 year, we studied more than 500MWp of plants across the country to identify the degradation patterns in plants and kinds of defects observed. Data for 3 plants from 3 states is shown in the figure.

 

 

The above results were evaluated through on-site EL imaging and IV curves measurement for spatially distributed random sample of modules.

The EL image above shows a module with severe cracks that could have been developed due to  mishandling during transportation or installation or during plant operation. It's quite possible that the module or the pallet fell down. It is also commonly observed that site workers may walk over the modules causing these kinds of cracks

This El image above shows module with small cracks that could manifest over years due vibrations caused due to loose fittings or during plant operations.

 

This image is of a module with solder contact failure shown by the darkened area around the busbar. It is a reliability issue and can also lead to loss of power. It may happen because either the stringing ribbon is not soldered at enough number of points or soldering points get weakened over the years due to thermal stress or simply because technicians at manufacturing end are not trained to carry out proper quality checks of soldering strength of stringing ribbons.

 

This image is of a module suffering from potential induced degradation (PID). High potential stress in modules causes leakage current to flow from glass to cell due to leakage of Na+ ions which damages the junction. PID is most often associated with high negative potential with the ground. It impacts the performance of modules and keeps increasing over time.

 

High degradation in early years of operation as well as the wide mixture of defects shows that quality has been compromised at every step of the value chain such as procurement, shipment/transportation, handling during installation, sub-optimal engineering practices and lack of in depth knowledge in best O&M practices. As a result, a lot of solar asset owners are suffering from poor generation and loss of revenue. This lack of accountability and poorly expressed warranties is also resulting is uncertainty over the ownership of the issues observed in PV plant components such as modules, structures etc.

This suggests that if India is to reach its target of 100 GW solar power, it's imperative that we establish stringent quality control measures along with the necessary policy changes.