For an operating Photovoltaic Plant, the main exogenous limitation to optimal performance is represented by the environmental conditions and by soiling presence on the PV module surfaces. The main environmental parameters as solar radiation.

The basic feedstock of the system, and temperatures, influence performances of the plant, and less-heralded factors such as wind speed, wind direction, rainfall, concur to generate the environmental conditions determining the potential expected plant yield against which actual plant performances are measured. 

For this reason monitoring of the environmental characteristics of the site and, on the other hand, of the PV module itself, can give parameters to calculate the efficiency of the power plant. 

The key variables to be monitored are: global irradiance, air temperature and module temperature, diffuse irradiance. Also wind speed, wind direction, rain and storm distance are key factors in the field of risk prevention during extreme events.