Taking the temperature of bifacial modules: Are they warmer or cooler than monofacial modules?

Bifacial cells and modules collect light falling not only on the front side of the panels but also on the rear; this additional collection of light increases the total absorbed irradiance, and accordingly the generated current. One of the remaining questions is: what temperature do bifacial solar panels operate at compared with monofacial panels? The extra light absorption at the rear will heat up the modules more, but at the same time, the parasitic heating by the absorption of infrared light is reduced, because infrared light is mostly transmitted through the glass–glass panels. In this paper, different bifacial and monofacial cell and module architectures are considered for the calculation of the energy spectra for all heat loss and absorption processes and the effective heat input. The heat transfer coefficients and the heat capacities of modules with different rear panels are given. Actual module temperatures for different layouts are presented and discussed for low- and high-irradiance (diffuse/direct) conditions in the Netherlands.

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