Energy production of photovoltaic systems: Fixed, tracking, and concentrating

Abstract

This work compares the energy production (EP) of four photovoltaic system configurations: fixed, 1-axis and 2-axis tracking flat plate, and concentrating photovoltaics (CPV). The EP comparison is based on real performance data from systems installed in Spain in 2009. These systems are located close to each other but house different configurations. Many of the systems analyzed are new installations in 2008, including two of the largest CPV systems in the world that together have 9.3 MW and represent more than 50% of the world's total CPV. The EP analysis shows: (1) compared with the fixed flat plate systems, 1-axis and 2-axis tracking flat plate systems have 22.3% and 25.2% gain in the annual EP, respectively. These real EP gains are less than 32.1% for 1-axis and 38.7% for 2-axis tracking, which are the predicted gains when only considering the difference of captured illumination by these configurations (based on the data from Photovoltaic Geographical Information System (PVGIS)). (2) The EP from CPV systems is quite close to that from fixed flat plate systems. This differs from the predicted 16.1% gain from CPV when only considering the illumination difference. Besides comparing the energy production, the performance ratio (PR) is also estimated and analyzed for the different configurations, based on the best available irradiation data. PR measures the agreement between the operation of a real system and of an ideal system that only considers the nominal module efficiency loss. The analysis shows the PR decreases in the order: fixed, 1-axis, 2-axis tracking flat plate, CPV.