Effect of timing and voltage dependency on inverter sizing

The effects of environmental data time steps and inverter’s voltage dependency on optimum inverter sizing are investigated in this paper. Three sites in the Europe with the specific climates and two detailed inverter characteristics including its dependence on the DC voltage during the operation are taken into account to demonstrate the differences in the inverter sizing required to allow for the site and inverter specifics. A model of a PV system linked to an inverter is developed to assess and optimise how the different factors influence the correct sizing of a given PV system. The environmental data with time resolution higher than 10 minutes is recommended since low frequency data (hourly data), which might ignore the irradiance peaks and underestimate up to 2.7% of total annual energy at high irradiances, cannot guarantee the correct sizing ratio of inverter. Inverter efficiencies change up to 1 to 3% as a function of input voltage which needs to be considered in inverter sizing. The overall inverter behaviour is also crucial in order to size appropriately. It is shown that some inverters perform better with undersizing, some better with oversizing.