Improving the profitability of grid-connected photovoltaic systems by sizing optimization

The profitability of grid-connected photovoltaic (PV) systems and, hence, the penetration of this renewable energy source in the society, can be improved by sizing optimization, just finding a correct matching between the PV array peak power and the inverter nominal power. However, PV designers usually base the system sizing on rule-of-thumbs or rough estimations, which implies losing the opportunity of developing more cost-effective installations with the same system components. In this paper, a sizing case study in Aguascalientes, central México, is analyzed based on solar irradiance and ambient temperature data of 10 years. A crystalline silicon PV module and a state-of-the-art string inverter are characterized to model the rated energy yield of typical trading/industrial grid-connected PV systems. An economic objective function is proposed to optimize the system size, which accounts for the cost of inverters, cost of the rest of elements of the system and cost of electricity for the customer. Results indicate that array-to-inverter power sizing ratios between 1.13 and 1.19 as a function of the system costs can optimize the profitability. The study can be replicated to other locations, PV module technologies and grid-connected inverters.