Analysis of Irradiation Differences on Substring Level of Modules in Solar Parks

This paper analyzes solar irradiation on the substrings of modules in solar power plants. Substring Maximum Power Tracker (SubMPPT) is an upcoming technology to reduce electric power losses caused by bypass diodes in partially shaded modules. Current research is investigating various inhomogeneities of irradiation in solar parks. Due to distances of rows of photovoltaic (PV)-installations irradiation is not homogeneous within the rows and therefore not for the modules and substrings. Especially for technologies like SubMPPT it is important to have a precise knowledge of partial shading and inhomogeneous irradiation within the substrings. Unfortunately, there is no simulation for the irradiation on the substrings of a solar power plant available. The thesis that SubMPPT can increase the area utilization factor of PV parks by increasing the yield with partial shading is investigated. The aim is to determine the energetically and economically optimal row spacing for solar parks with SubMPPT. This paper investigates the impact of row distances on the direct and diffuse irradiation plane on array (POA) within the substrings of modules in solar parks. The results show a significant difference of up to 85 % of monthly global irradiation between the upper and the lower substring of a module in the middle of a solar park with single-row arrays when the row distance is reduced to 1 ????. The results indicate that reducing row spacing increases inhomogeneities of global irradiation within the modules and results in energy losses due to the series connection of substrings.