Optimising PV array performance using real time measurements

BP Solar is involved in long term studies on IV swept, maximum power point tracked or grid connected arrays at currently 67 sites worldwide. Recent studies have shown that many PV arrays can suffer lower performance than expected due mainly to BOS limitations like inverter efficiency, mismatch, shading, thermal losses and V/sub MAX/ tracking accuracy. This paper discusses mathematical methods used to analyse instantaneous or averaged array data in real time to determine when arrays are not performing optimally and shows how to help identify what is causing the loss. Empirical equations are introduced to help determine what power the system should be producing during each measurement period.