This report presents the results obtained by RSE in evaluating the energy performance of Concentrated Photovoltaic (CPV) modules. These performances are significantly influenced by both the construction characteristics of the modules (such as cell types, optics, and receivers) and environmental variables such as temperature, direct irradiation, and its spectral content, as well as potential degradation and soiling effects on the modules.

One factor impacting performance is the soiling of the module surfaces. Currently, its effects are assessed using a method that monitors the ratio between the power of the test module and that of a reference module kept clean. Since this method is challenging to apply in real installations, where continuous cleaning of the reference module is difficult to ensure, RSE has developed a method (referred to as the “RSE method”) in previous years that avoids using a reference module.

Thus, at RSE’s testing facility in Piacenza, tests were conducted to validate the RSE method and analyze its associated uncertainties. Additionally, tests were performed to study the reliability and energy performance of four commercially available CPV modules with varying characteristics in terms of optics, cells, and/or electrical layouts.

For each module, initial indoor measurements were taken to identify certain electrothermal parameters necessary for subsequent outdoor performance evaluations. Outdoor tests were then conducted to characterize the electrical and energy performance of the CPV modules, including measurements of angular acceptance (a key parameter impacting the reliability and cost of the solar tracking system) and performance monitoring at different times of the year under Standard Test Conditions (STC) and Standard Operating Conditions (SOC), according to the CEI EN IEC 62670-3 standard. Finally, the energy performance index (Performance Ratio, PR) for each module was evaluated in accordance with the CEI EN IEC 62670-2 standard, calculated as the ratio between the energy generated under operational conditions and the energy estimated based on the power declared by the manufacturer.

The results indicate that the power values under Standard conditions are lower than those declared by the manufacturer, but no component degradation was observed during the observation period. The PR values ranged from 67% to 72% based on the manufacturer’s declared STC power, and from 75% to 78% based on RSE’s estimated STC power during the testing. These results demonstrate the adequate reliability of the CPV modules.