Add estimation of bifacial gain BG to Sankey diagram

[kjs55]

PVsyst v7.2.10: Many PVsyst users and other PV stakeholders see the bifacial insolation gain in bold font in the PVsyst Sankey diagram and think this is the bifacial gain BG. However, this is incorrect & arguably misleading. A better (DC) estimate of BG is to multiply this insolation gain by the PV module's nominal (or nameplate) bifaciality factor. So, perhaps PVsyst can show this adjusted value on the Sankey diagram and put it in bold font instead. This suggestion is compliments of T. Townsend. Of course, this is still only an estimate of BG, as the true BG comes from running the simulation twice - once for bifacial and once for monofacial (i.e., bifaciality turned off - effectively a bifaciality factor of 0%) - and dividing the energy output metric of interest (e.g., AC energy injected into the grid, E_Grid) of the former simulation by that of the latter. The main suggestion here is to reduce the common misinterpretation of BG that exists due to the design & formatting of the present PVsyst Sankey diagram. Thanks!

[Michele Oliosi]

Hi thanks for the suggestion, it makes sense. We will consider this as a possible improvement of the report.

One worry might be users thinking that this new percentage IS the bifacial gain.. this is not what we want of course. But we can try to use a very clear denomination.