Performance Analysis of String and Central Inverter based Ideally Designed Utility scale Solar PV Plant

Abstract

As the PV industry continues to search for opportunities to reduce the costs associated with capital and operating expenses the choice between the two designs will become more important. String inverters can capture performance in more detail than central inverters; this may lead to improved performance for sites with irregular terrain and additional plant diagnostic capability. The purpose of this study is to conduct an independent research on two Utility - scale solar Photovoltaic systems of 2 MW each installed and commissioned at Anand, India Latitude: 22.298360; Longitude: 72.723246, one with a central inverters and the other with string inverters, to determine their comparative performance characteristics in real, outdoor conditions. This paper presents experimental data that supports the fact that string inverters can outperform central inverters in unshaded, shaded and all climatic conditions. Our study shows for irradiance levels greater than 50 W/m2 and less than1200 W/m2, the string inverter system produced an average of over 2.5% to 3.5% additional power than the central inverters, and in partially shaded, cloudy and Monsoon conditions the string inverters exceeded the Central system by an average of 4% to 6% more power.