Hot String and the Cool Module: Case Study of Default Detection in PV Systems byMeans of IR Photography

摘要

IR photography was used for the inspection of a PV system on the facade of abuilding. The IR photographs showed five PV modules having a temperature that was significantly higher than that of neighboring modules. The open-circuit voltage and short-circuit current of the strings in the PV array were measured. It was concluded that a single module was connected in reverse in the string containing the hot modules. At the time the IR photograph was taken the PV inverter was not active and the PV array was effectively short-circuited. Thus the energy generated by the modules of the array was dissipated in the string with the module connected in reverse, which lead to the observed rise in the module temperature. The resulting current-voltage curves of the PV array are calculated using models of the electrical characteristics of multicrystalline Silicon modules.