Tracker Terrain Losses

This paper reports on a study to quantify the scale of energy yield losses due to variable terrain and to determine how much of the loss can be reduced by advanced tracker technologies. The study uses a single-axis array in Hopewell, NC, which has and average 4% southwest slope. The site was simulated with trackers in two models to predict the theoretical best and worst case scenarios. In the first model the trackers are in a virtual mono-plane and in the second model the trackers follow the terrain but track as if in the same plane. The results were inconclusive indicating the models did not have the required accuracy to differentiate between the two simulations. The models bin tracker rotations into coarse 10° increments before calculating the shade used to determine the irradiance input and energy output. Future work has already begun to geometrically model the shade for each tracker position so irradiance input and energy output are sufficiently accurate to evaluate the terrain loss. Then if sufficient samples can be studied, we hope to present a simplified correlation that can be applied to 2-D models.