Long term operational performance and experimental on-field degradation measurement of 10 MW PV plant in remote location in India

Abstract

The paper presents extensive monitoring, detailed long term operational performance and on-field degradation measurement of utility scale grid connected 10 MW solar photovoltaic (PV) plant in real operating conditions. Different performance indices are evaluated incorporating IEC standard 61724 guidelines based on actual plant monitoring data (incident solar irradiation, ambient and module temperature and generated electrical energy) from January 2016 to December 2020 (period of five years). The annual average reference, array and final yield, performance ratio, capacity utilization factor, array capture and system losses, PV array and system efficiency of the plant were found to be 6–6.7 h/day, 4.83–5.1 h/day, 4.69–4.86 h/day, 72–74%, 19–20%, 1.02–1.33 h/day, 0.15–0.156 h/day, 12% and 11% respectively. Degradation of fielded modules is assessed by visual inspection and I-V curve tracing. Correlation of I-V characterization with electrical parameters of visually degraded installed PV modules is also presented. The calculated linear degradation rates varied from 0.97 to 1.52%/year in modules with considerable bird dropping, 1.33 to 1.61%/year in modules with light EVA discoloration, 1.6 to 1.86%/year in modules with glass breakage, 2.31 to 3.94%/year in modules with glass breakage and dark EVA discoloration, and 2.97 to 5.8%/year in modules with glass breakage and cell cracks. The annual linear degradation rates were found to be in the range of 0.9 to 1.1%/year for normal fielded modules with no visible degradation and 0.97 to 2.9%/year for visually degraded modules with mean and median values of 1.8%/year and 1.6%/year with six years operational period. The levelized cost of electricity, simple and discounted payback period and return on investment were found to be 4.05 Rs, 5.5 years, 11 years and 62.22% respectively. Annual CO2 savings of the plant is around 16,000 tons and CO2 emission reduction potential of installed pc-Si technology is found to be 1.6 tons/kWp.