A technoeconomic feasibility of inverter selection for MegaWatt(MW) scale grid connected solar photovoltaic power plant

Abstract

Renewable energy systems have become a need for today's time. But their techno-economic feasibility is one major concern if they are to compete with other conventional energy systems. For this reason, various selection techniques have been prepared for their design, operation, and control. The yield of a solar photovoltaic(PV) plant depends on various atmospheric parameters like solar radiation falling on the site, cloud cover, ambient temperature and duration of sunshine hours. Along with all these parameters, the quality and efficiency of equipment's used and the sizing of this equipment for a reference capacity of the plant also affect the solar plant yield. The appropriate sizing of the equipment for an optimum yield is dependent on the atmospheric parameters mentioned above. So, it becomes very much necessary to take these factors into consideration while designing a solar photovoltaic power plant. One such equipment, whose sizing depends on these factors, is the inverter which decides the AC output of the plant. The inverter sizing affects the net solar PV plant yield over a period of time. Higher inverter sizing equaling the DC capacity that is at an AC to DC ratio of 1:1 may improve the yield of the plant but may not be financially viable for the long run. Lower inverter sizing, on the other hand, will reduce the energy yield of the plant due to energy capping but will reduce the initial investment cost of the plant. This paper presents a methodology to select the size of the inverter for maximum financial return using an energy estimation software and financial model. The Internal Rate of Return (IRR) is used as a financial model for checking the feasibility of the inverter sizing being selected. The methodology is tested for various district locations in the state of Maharashtra in India to get the optimum sizing of the inverter and applied to a case study plant of 634 kW-DC capacity in Latur district of Maharashtra state.