Comparison of solar modeling data to actual PV installations: Power predictions and optimal tilt angles

Solar tracking mechanisms were developed to maximize the energy yield of solar cells. Software models can help predict the optimum tilt angle to point the single axis tracker for maximum energy output for the entire year. We used modeling programs to predict the optimal angle and for this region they do not agree. In 2009 Auburn University designed and built a test structure that allowed us to conduct comparison of these models. There are six test panels, five panels are rotated in a single axis azimuthally at the tilt angles of 20°, 25°, 32° (latitude), 40°, and 50°. Another panel is a fixed control panel facing south at latitude tilt. The system has collected data for over one year. Also data collected at the Lee County´s T.K. Davis Justice Center´s 16.6 kW grid-connected solar array system is compared to the performance data to the results of three photovoltaic modeling programs used before and during installation of the system. This research will shed light on the accuracy of modeling programs and discuss reasons behind program results variations.