Characterizing Electrical Output of Bifacial Photovoltaic Modules by Altering Reflective Materials

Bifacial photovoltaic (PV) modules offer potentially enhanced power output over conventional modules due to their reported ability to harvest reflected radiation, increasing output up to an additional 30%. However, this enhancement has yet to be confirmed in the literature. This paper reports on a study comparing the power output of two nominally identical 700 W photovoltaic arrays utilizing equivalent system components and data logging equipment with varying configurations of reflecting geometries and materials. This study was undertaken at the Appalachian State University Solar Research Laboratory in Boone, NC, which houses two Class 1 pyranometers and pyrheliometer. PV power was reported under well-quantified irradiance conditions, including direct beam fraction. Six trials over six months (November-April) with varying reflective materials and geometries revealed that different reflecting materials did not significantly change power output. Mounting an array at 0° did adversely affect power output compared to the array at a 36° angle relative to horizontal using the same reflective material. Additional studies with varied materials, panel locations and geometries different from those tested may improve the power output.