Impact of Performance Degradation and Capital Subsidy on the Revenue of Rooftop PV System

Offering capital subsidy is one of the most recognized techniques to promote solar photovoltaic (PV) systems for investors. Most of the nations have offered subsidies to the investors, who are willing to invest and develop the PV systems (system peak capacities ranging from small-scale wattage to large-scale multi-megawatt). This paper tries to investigate the influence of subsidy on the revenue generated by a PV plant. For a clear understanding of the subsidy influence, two PV system cases (the first one is without capital subsidy, and the second one is with 15 % capital subsidy) are considered. The revenue generated by the PV plant is estimated considering the approved grid feed-in tariff rates set by the Electricity Regulatory Commission separately for each case depending on the PV plant capacity. Another known fact is that there exists performance degradation in the PV plant to a maximum extent throughout its lifetime. Hence during the evaluation of revenue, the energy degradation over the PV plant lifetime, i.e., 25 years is considered. Focused results for analyzing the system include energy yield for the first year, energy yields for the rest 24 years of life considering degradation, yield factor, capacity factor, revenue generation, and payback periods. With the analysis of the parameters as mentioned earlier, the revenue benefits of PV systems with and without capital subsidy is discussed, and relevant conclusions were made.