Estimation of Photovoltaic Module Temperature Rise

The photovoltaic module temperature rise is expressed by an approximate equation of solar irradiance, wind direction and velocity. For this purpose, the experimental data were collected from the 750kW test equipment over 2 years. The data were averaged for 30 minutes periods and divided into monthly groups. Wind directions were classified into 4 categories corresponding to the ranges within ±45 degrees of north, south, east and west, and wind velocities into sections of 1m/s. The correlation between module temperature rise and solar irradiance was used to obtain an approximate equation on wind direction and velocity for the standard solar irradiance(l.0kW/m2). By relating this equation to a linear function regarding solar irradiance, an approximate equation for module temperature rise was derived. The temperature rise calculated by using this approximate equation was compared with measurements. As much as 82 percent of the calculations are within ±2°C of the corresponding measurement, while 96 percent fall within ± 4°C. This suggests that the approximate equation will be sufficiently accurate to evaluate averages over relatively long periods, such as for calculation of system efficiency and simulation.