Outdoor evaluation of power output improvement of the bifacial module

Comparative outdoor measurements of bifacial and monofacial modules were undertaken. Modules were installed in fixed positions. First, south oriented at 30° to the horizon - stand-alone and in a solar field system. The second vertically at different azimuth orientations. To separate the effects which are not connected with the rear photo response but can cause differences in energy generation gain, additional measurements were undertaken: efficiency dependence on irradiance, angular dependence of module short circuit current, and temperature coefficient of power. The energy gain for a stand-alone south oriented at 30° module exceeds 20 % at underlying surface albedo ~50 %. It is ~5 % higher than for the same module in a solar field where the rear contribution is affected by roof shadowing due to neighboring modules. Vertical bifacial modules with different azimuth orientation always generate significantly more energy than mono-facial modules with the same orientation.