Chapter 5
Page 17: Figure

Fig. 4: Computer simulation using solar radiation data shows how the output of two photovoltaic power systems cold be added to the utility's generation to help meet peak electric demand in the summer. The fixed-tilt array faces south and is tilted from the horizontal at an angle equal to the site's latitude. The tracking array uses motors and gear drives to point the array at the sun throughout the day. Depending on location, the photovoltaic system with the 2-axis tracking array receives annually 25% to 40% more global solar radiation than the fixed-tilt photovoltaic system and provides more power for longer periods. This must be weighed against the higher initial cost and maintenance required for the tracker.