10.1.1 Improvement of Irradiance by Tracking the Sun
Irradiance on a solar generator can be improved by tracking the sun’s path from sunrise to sunset. In the case of Berlin,
Germany the yield increases by 25-30% in summer and by 0 -10% in winter. Most single-axis tracking devices follow the sun’s path from east to west (azimuthal tracking) at a fixed inclination. Two axis tracking devices also follow the seasonal change in the elevation of the sun’s path. An example of a two-axis tracker in comparison to a fixed PV-generator is shown in Fig. 10.1. The costs for a tracking device are considerable. In many cases the additional yield is not able to compensate for the extra costs (Erturk 1997). In some parts of the Third World (e. g., India) a high cost-efficiency was achieved by manual tracking (e. g., every 3 hrs), due to low costs of labor.