A novel shading analysis method for PV systems using sun path plots and high resolution performance data

This paper presents a technique for identifying and quantifying shading losses in PV systems. Five minute interval monitored data from domestic UK PV systems is used to assess the effects of trees and other shading objects on annual energy generation. Poor performance is identified from the relationship between in-plane irradiance and performance ratio. Shading events are identified by plotting the occurrences of poor performance on a ‘sun path plot’ of solar azimuth and elevation axes. Poor performance which concentrates about particular sun positions is identified as shading. Once identified, the energy loss due to shading is quantified.