Copyright © 2013 SciRes. ENG Testing Bifacial PV Cells in Symmetric and Asymmetric Concentrating CPC Collectors

Bifacial PV cells have the capacity to produce solar electricity from both sides and, thus, amongst other advantages, allow a significantly increase both in peak and annual power output while utilizing the same amount of silicone. Ac-cording to the manufacturer, the bifacial cells are around 1.3 times more expensive than the single-sided cells. This way, bifacial PV cells can effectively reduce the cost of solar power for certain applications. Today, the most common application for these cells is in stationary vertical collectors which are exposed to sunlight from both sides, as the rela-tive position of the sun changes throughout the day. Another possible application is to utilize these cells in concentrat-ing collectors. Three test prototypes utilizing bifacial PV cells were built. The initial two prototypes were built for in-door testing and differed only in geometry of the reflector, one being asymmetric and the other symmetric. Both proto-types were evaluated in an indoor solar simulator. Both reflector designs yielded positive electrical performance results and similar efficiencies from both sides of the cell were achieved. However, lower fill factor than expected was achieved for both designs when compared to the single cell tests. The results are discussed and suggestions for further testing are presented. A third prototype was built in order to perform outdoor evaluations. This prototype utilized a bi-facial PV cells string laminated in silicone enclosed between 2 standard glass panes and a collector box with an asym-metric CPC concentrator. The prototype peak electrical efficiency and temperature dependence were evaluated.