The Government of India has set an ambitious target of achieving 100 GW of solar installations by 2022, of which 40 GW is earmarked for rooftop solar. While the current approach towards this goal has been to substantially increase the installed capacity (kWp) of rooftop PV systems. It is important to ensure that these rooftop solar systems perform optimally with high specific yields (kWh per kWp). Understanding this need to address concerns regarding the quality of rooftop PV installations, GIZ undertook the “kW to kWh” technical study to conduct a quality evaluation of selected rooftop solar PV systems across India.

The kW to kWh study involved the on-site analysis of 40 rooftop PV plants of various capacities along with analysis of the contracts, warranties, and O&M practices. It involved consumer segments such as government, educational, residential, and commercial rooftop PV plants, including both, subsidised and non-subsidized PV plants. The analysis majorly included activities such as visual inspection of the plants, soiling factor estimation, I-V curve tracing, infrared imaging, electroluminescence tests, contract & documentation review, interviews with the EPC, O&M contractor and site owners. Building on the success of this study, GIZ is currently extending the analysis to additional 60 sites across 9 states in India. It will now include causes for cell cracking by analysing aspects related to the logistics of PV modules and mounting structures. 

It is no secret that the results from the study have highlighted significant shortcomings in installation and maintenance practices for rooftop PV systems such as mechanical damages in PV cells, soiling, improper plant design, and construction among other things which were present in a significant number of plants, as seen in figure 1. Issues such as the soiling of modules caused an estimated loss in the generation of up to 19% in some PV plants. Additionally, sub-par operation and maintenance of these rooftop PV plants was another aspect that contributed to a significant loss in energy generated, due to poor practices and lack of proper warranty and replacement mechanisms in place for damaged components (figure 2).

Based on the findings, five major retrofitting actions were suggested: (i) Re-sorting of modules and strings for better performance, (ii) Increasing the modules cleaning frequency depending on the soiling factor, (iii) Replacement of damaged modules while still under warranty, (iv) Shortening of module strings to counter near shading, (v) Increasing the albedo factor of the surroundings.
It becomes imperative that all issues identified are properly looked into by project developers, EPC companies, DICSOMs, and owners to ensure the longevity of their rooftop PV plants, and to facilitate further uptake of rooftop solar in India by moving away from just capacity addition (kW) to ensuring optimum generation (kWh).

For more details on the kW to kWh technical study, kindly visit: https://kwtokwh.in/