Design Considerations and Measured Performance of Nontracked Mirror-Augmented Photovoltaics

Costs associated with conventional photovoltaic (PV) installations (module manufacturing, mounts, wiring and installation labor, etc.) scale linearly with system area, and prudent design practices for increasing the light harvesting may significantly enhance the power output per unit area and cost per watt. The use of PV modules that have been augmented by the addition of a solar mirror provides an opportunity to improve light harvesting of a PV module and cost-per-watt considerations if the mirror is less expensive than the relative increase in power. In order to harvest greater insolation, an optimized design configuration between a flat-panel module and mirror is necessary for a fixed (nontracked) mirror-augmented photovoltaic (MAPV) system. A series of irradiance and energy harvest calculations were developed to screen various MAPV design configurations. We employed optical ray-tracing simulations to determine irradiance nonuniformities on the fixed MAPV system. The simulated results are compared with outdoor experimental field trial results. Over a three-month period of study, the fixed MAPV system produced 12% more power than an equivalent nonaugmented panel. An adjustable angle mounting system known as “time machine” was used to estimate yearly power production by adjusting the relative position of the MAPV system to represent varying times of the year. Current--voltage (I-V) curve tracing of test modules was performed during the field trials on augmented and nonaugmented modules for comparison. The experimental time machine result is in agreement with the irradiance simulation, which shows a gullwing curve of annual power output with peak production on the equinoxes and reduced production on the solstices.