Dependence of Photovoltaic Module Performance Indicators on Operating Temperature and Irradiance

Condition of photovoltaic (PV) modules can be monitored by using measured current–voltage curves. The curves can be used to calculate numerical indicators that jointly can reveal possible changes in the condition of the PV modules. Such indicators are tied to the shape of the current–voltage curve. However, the changes in operating irradiance and temperature are known to affect the shape of the curve as well. Thus, also the operating conditions have an impact on the numerical values of the performance indicators. As a consequence, any such impact reflects on the diagnostical results. For this reason, it is important to investigate the dependence of the performance indicators on the operating conditions. This study addresses this issue by investigating four performance indicators in terms of their temperature and irradiance dependencies. The results assist in developing condition monitoring strategies of PV systems.