Discrete two-positional tracking of solar collectors

Abstract

Northern European regions, such as Estonia at 60° latitude, receive about 980 kWh m −2 y −1 of solar radiation. These low insolation levels motivate solar collectors to be equipped with a tracking mechanism for an increased yield. Classical active tracking is complicated and energy intensive, negating tracking benefits for PV modules and thermal flat-plate collectors. This paper describes mainly the performance of PV modules with daily two-positional tracking. The symmetrical and asymmetrical positions about the north–south axis are analyzed, corresponding to the positions of sun in the morning and in the afternoon. The tracking drive is simple and requires a minimum energy input during the brief daily triggering of movement. Results indicate that the seasonal energy yield is increased by 10–20% over the yield from a fixed south-facing collector tilted at an optimal angle. The results are based on long-term solar data measured at the Tartu-Tõravere Meteorological Station in Estonia, confirmed by experimental testing during summer 2004 and 2005 in Tallinn University of Technology.