  Concentrator Photovoltaic (CPV) systems use high efficiency multi-junction
solar cells with efficiencies >40%, but the module efficiency is often much
lower. The increased complexity of a CPV module, with optics, receiver and the
tracker gives an increased probability that faults will arise during the
operational lifetime. In addition, a location like India has varied atmospheric
conditions that further complicates the diagnosis of faults. It is therefore
important to decouple effects due to the external environment (such as the
atmosphere) from effects due to the degradation of the module. By applying a
computer model to outdoor CPV test data in Bangalore, India we have established
a method to assess the performance of the CPV module and finally we present a
method to diagnose faults in the module.
