Study of the shading effects on photovoltaic (PV) modules in building integrated photovoltaics (BIPV)
Document typeMaster thesis
Rights accessOpen Access
This thesis work focuses on the effect of shading on the photovoltaic (PV) modules in building integrated photovoltaics (BIPV). The main objective of this thesis work is to analyse and characterise the electrical and thermal behaviour of the PV modules when they are partially shaded, a circumstance which frequently occurs in photovoltaic installations in buildings. The PV module technologies considered in this research are; Cadmium Telluride (CdTe), Copper Indium Selenide (CIS), amorphous silicon heterojunction, amorphous silicon simple junction, amorphous silicon triple junction, mono-crystalline silicon (Kyocera), mono-crystalline silicon (Suntech), mono-crystalline silicon back contacts and multi-crystalline silicon (Si-mc). The electrical and thermal measurements were done in outdoor conditions to obtain data in real operating conditions. Each PV module technology was exposed to different shadow patterns and the I-V curves measured. In order to correct the measured I-V curves to the same testing conditions, the IEC 60904-1 standard was considered, in which it is necessary to know the values of the temperature coefficients, internal series resistance (Rs) and curve correction factor (k). The shadow patterns resulted into the reduction of the electrical characteristics (current, voltage and power) for each module technology. The shading also resulted into the reduction of the maximum power of each module technology and there were no hot spots in the modules. The magnitude of the electrical parameters of the PV module technologies due to shading depends on the shadow patterns, arrangement of the cells and location of bypass diodes in the modules. The thermal characterisation indicates that shading resulted into the reduction of the module temperatures in comparison to the unshaded module and there were no hot spots in all the module technologies. Therefore, all the module technologies tested are capable of being applied in building integrated photovoltaics (BIPV) since they are not affected by hot spot phenomena in the real operating conditions. The comparison of the different PV module technologies with the same shadow patterns indicates that the PV modules perform differently with shading. The results indicate that some PV module technologies which perform well in one shadow type do not perform well in another shadow type. In the application of BIPV in buildings, shading should be taken as a priority since it greatly affects the electrical and thermal characteristics of the modules. The nature of the shadows in a location should be considered before selecting the PV module technologies to apply in the BIPV system.