3.1. Electrical performance

During this study it was not possible to measure the cells temperature directly since the trough structure is closed. Hence, the average water temperature running inside the thermal absorber at the moment of the electrical efficiency measurement is presented instead. Using the maximum electric power extracted by Solar8 together with the incident beam irradiation it was possible to estimate the electrical efficiency behaviour of the system depending on its working temperature (Fig. 2).

From the linear representations of the electrical performance it is possible to estimate that the electrical efficiency is 8.3% per active glazed area and 6.3% per total glazed area at 25°C average water temperature running inside the thermal absorber. The slope of the electrical performance trend lines fits fairly close the classical 0.4% drop in efficiency per °C in cells temperature increase. For this study, active area was defined as the maximum glazed area the system can make use of.