Modelling the efficiency of terrestrial photovoltaic systems

A computer simulation capable of investigating the interrelationship of module packing densities and module inclination angles and their effects on overall energy yield for a given PV system installation area is presented. It is demonstrated that the simulation is a useful tool in the optimization of proposed system designs, the analysis of electrical performance and, moreover, the prediction of the occurrence of degenerative system effects such as hot-spots. In one case, it is shown that increasing the system height to module spacing ratio from 0.18 to 0.24 results in potentially severe shading effects. Results for Seville (Spain) and Loughborough (UK) are compared. The potential pros and cons of tracking systems are demonstrated, in that elevation only tracking results in an annual irradiance harvest reduction of 0.4% in Loughborough and increase of 3.4% in Seville. Varying module inclination angles shows how significant irradiance losses can occur when static PV arrays are not optimally mounted, reducing the inclination from 40 degrees to zero results in an annual irradiance harvest reduction of ~20% in Seville and ~14% in Loughborough.