GlobBak (W/m2) exportation boundary

[sherro]

Hi Team,

We are contemplating whether the GlobBak boundary recreated and traded to csv reflects precisely the compelling irradiance on back side of a bifacial module that it is getting, or it should be increased by the bifaciality factor. e.g: GlobBak = 200 W/m2 x 0,7 = 140 W/m2

This inquiry comes from the computation that SANDIA technique does of Voc all year long. They say we should increase it yet we don't know, truth be told we accept the bifaciality influences just on the yield change however not in irradiances, so Voc is influenced by 200 W/m2 in the model, thus cell temperature varieties, to fabricate a Voc = f (Irrandiance, cell temp) fundamentally.

Much appreciated.

[Bruno Wittmer]

The variable GlobBak represents the effective irradiance on the rear side. It includes direct and diffuse sky irradiance as well as the irradiance reflected from the ground. For all these three irradiance components the shading and IAM losses are accounted for.

The bifaciality factor is a property of the PV module. In the simulation it is applied when calculating the photovoltaic conversion, so it is not yet reflected in GlobBak. The calculation applies the bifaciality factor to GlobBak, and uses this result as input for the single diode model.

For the thermal behavior the simulation uses the same approach for both, monofacial and bifacial simulations. In fact, the irradiance both modules receive is the same, the only difference is that the bifacial module removes a little more energy when operating, which would mean that its temperature will be slightly lower. This is not yet taken into account in the simulation.