Performance analysis of PV modules of various technologies after more than one year of outdoor exposure in Rome

The paper deals with an extensive PV modules monitoring activity carried out at the outdoor station ESTER of the University of Rome Tor Vergata. The purpose of the work was to evaluate and compare the performances of PV silicon modules of polycrystalline and amorphous technologies during a medium term outdoor exposure at optimized tilt angle, facing south. Two PV modules, one polycrystalline by Kyocera and one double junction amorphous by EPV Solar have been exposed since May 2009. A complete characterization of the weather conditions at the site during the test has been performed and the most relevant parameters for the performance comparison of the two technologies have been derived. In order to compare different technologies and power productions, the energy Yield (Y) and Performance Ratio (PR) for the two modules have been evaluated on a monthly and yearly basis. The typical seasonal trend of PR has been observed for the polycrystalline module, essentially due to the temperature influence on the module performances. For the EPV module, instead, a degradation trend has been observed for the first months of operation. Subsequently a significant recovery in the PR and energy production has been registered.