Abstract
We present an approach to determine the potential energy gains of
flat plate non-concentrating photovoltaic systems for the case of
two-axis tracking and two inclination angles with fixed orientation
(assuming biannual adjustment) compared to the configuration of single
fixed optimum angle. The calculation is based on the Photovoltaic
Geographic Information System (PVGIS), which integrates modelling
tools with the pan-European solar radiation database. The results
indicate that in the case of a PV system with two seasonal inclination
angles, the maximum yearly gains, compared to the single fixed optimum
angle, do not exceed 60â70 kWh per kWp in the Mediterranean region,
while in the Baltic and North Sea regions this configuration gives
less than 20 kWh extra. For the case of two-axis tracking, the relative
energy gain compared to single fixed optimum angle is highest in
the Northern latitudes but the absolute gain is much higher in the
South. Typical yearly gains in Portugal and the Mediterranean region
are in the range of 400â600 kWh per kWp. The smallest absolute
increase is found in the Northwest and Central Europe including the
British Isles, where it is lower than 250 kWh per kWp. For crystalline
silicon we also investigate the effects of temperature and shallow-angle
reflectivity on the comparison between fixed and tracking systems.
While both effects reduce the overall energy output, the temperature
degradation is stronger for tracking systems while the reflectivity
reduces output more for fixed systems. The combined effect is almost
equal for fixed and two-axis tracking systems.
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