Formulation of Efficiency of Inverters for Solar Photovoltaic Power Plants - Indian Case Study

摘要

Indian Government has set ambitious targets for solar PV of 100 GW under the National Solar Mission by the year 2022. The installed capacity has already reached 28GW as on March 2019. The inverter is one of the main components of solar PV conversion system. Due to varying irradiation profile in India, the inverters used in Solar PV applications are subjected to varying levels of DC input power. At present two weighted average methods namely EURO and California Energy Commission (CEC) efficiency formulae have been used by inverter manufacturers worldwide to evaluate the performance of inverters. These methods are representative of inverter efficiencies at Europe and California, thus cannot be suitable benchmarks to find out the conversion efficiency of the inverters in other locations. The present research and this paper proposes about introducing new weighting factors for calculation of inverter efficiency as per irradiation profile in India. As a step 1, for computing the weighting factors the data from Solar Radiation Resource Assessment (SRRA) stations implemented by National Institute Of Wind Energy (NIWE) is used and are categorized into five climatic zones. In step 2 validation of three inverters were done by calculating the weighted average efficiency of these inverters operating in all the climatic zones by considering the new weighting factors. Further in step 3, it was cross-compared with the standard values of EURO and CEC efficiency. In step 4, the modelled overall weighted average efficiency is subsequently compared with the actual measured weighted average efficiency. The measured DC Energy and AC Energy of the plant was used for this purpose. The proposed approach has been generalized to consider the irradiation profile of a particular location for calculating the inverter efficiency and hence it can provide significant insights related to the performance of inverters for the solar projects.