String level optimisation on grid-tied solar PV systems to reduce partial shading loss

Partial shading, commonly observed in domestic rooftop solar photovoltaic (PV) deployments, can be highly detrimental to the performance ratio (PR) of a PV system. Typically, for domestic installations, string-inverter or module micro-inverter configurations are deployed. While module level micro-inverters generally present a better response to non-uniform distributions of sunlight, they are still less common and therefore, costly in many emerging markets. String-level implementations, on the other hand, are widely deployed as they are less complex and cost efficient. In this work, the authors present an analytical and simulation framework for improving PR under partial shading conditions through alteration of string connections in a string-level inverter system. Results show up to 4.6% higher PR in winter months for a 42.24kWp system installed at Lahore University of Management Sciences, Lahore, Pakistan.