FIRTH, S.K., REES, S.J. and Lomas, K.J., 2005. A novel shading analysis method for PV systems using sun path plots and high resolution performance data. 20th European PV Solar Energy Conference, Barcelona, Spain, June 2005, pp.2005-2009.
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.