Mono c-Si Bifacial modules

[lcollura]

Hi,

We are a module manufacturer and would like to determine the best way to define a PV module in order for the most accurate simulations in PVsyst. Bifacial modules have a front power spec, same as standard panels, and also a rear power spec which varies form 5 to 30% additional power based conditions.

What is the best way to simulate a bifacial PV module? Can transmitted, reflected, diffused light and module orientation be simulated? Should different PV module definitions be entered corresponding to...say 10%, 20% and 30% gain in power to account for the rear power? Or is there another method to most accurately model a bifacial module?

Please advise. Specification sheet attached

Thanks

[André Mermoud]

Sorry, the bifacial behaviour is not implemented in PVsyst.

This would require a reliable evaluation of the reflected irradiance behind the modules.

For this, the whole geometry of the modules and their rear configuration should be described in detail, the reflection coefficients should be specified. This is a very complex computation, not possible in a general software like PVsyst. Moreover one can wonder from where the light could come: there is no possibility of beam component (except special cases with spaced cells and reflectors), and reflected diffuse is quasi-impossible to calculate in a simple way, and probably very low.

You can try to measure it using a solarimeter on the back side, in different locations of your array.

Now we should also emphasize that in a string of modules, the current is driven by the cell of weakest current. Therefore for representing a significant gain, the reflected irradiance should be uniform on the back area of a whole string of modules, which seems quasi-impossible.

NB: the only configuration which would eventually be possible to simulate would be vertical modules oriented east-west.

In this case you can use "mixed orientations" and define 2 different modules, one for the front and one for the back side of your bifacial modules.

[Arnaud Tarajeat]

Deat PVsyst Users,

Our next main release - 6.6.0 - , which includes bifacial modelling and 3D drawing entirely revisited, is now reading for testing.

If you wish to have a look at it and give a feedback, please send us a request to support(a)pvsyst.com and we will setup your account.

PVsyst Team