Diagnostic method of performance of a PV module with estimated power output in considering four loss factors

Recently, PV systems are rapidly spreading. It is necessary to establish a diagnostic method for maintenance of the PV systems. The authors are studying diagnostic methods of PV systems. Even if a PV module is normally operated, the generated power is less than the rated power. It means that the normal PV module has some kinds of loss in the generated power. These losses are caused by irradiance, reduction of sunlight transmittance on glass of module, temperature and series resistance. The generated power can be estimated by considering these four kinds of loss. The estimated power is calculated by subtracting these power losses from the rated line. As the results, the diagnostic method is devised by using the estimated power. And it is clear that the method can diagnose bit degradation of generated power on the module.