3d modeling Applying bifacial system

[leesujin]

Hello

In the case of using two-sided modules these days, there is an issue about calculating the efficiency of the back and adding it to the module capacity.
As far as I know, the efficiency of the double-sided module is applied only to the 2d model, but is there any way to simulate the power generation time by applying the double-sided efficiency in the 3d model?

Edited July 22 by leesujin

[Michele Oliosi]

Currently, the rear-side model of irradiance is two-dimensional (cross-section). However, it is compatible with a 3D drawing.

If you have a 3D drawing with a regular arrangement of tables, you can activate the 2D bifacial model to compute the rear side irradiance.

[leesujin]

Is it impossible to apply the rear system for modeling that is not arranged regularly?
I want to apply double-sided efficiency when installing solar power on the ground
But solar 3D modeling on the ground can't be represented in a regular arrangement

[Michele Oliosi]

Regularity is defined vaguely by PVsyst. If the system is approximately regular, e.g., patches of trackers or tables that are more or less evenly spaced, then this can be considered “regular” in the PVsyst sense. In that case, you can use the 2D bifacial model jointly with the 3D scene.

PVsyst will check the following points:

• The RMSD of the pitch distribution. If the RMSD is too large, PVsyst will throw an error. You can change the threshold of the error in the advanced parameters.
• Whether the tables are the same height. If there are differently tall tables, PVsyst will throw an error.
• Whether orientations have more than 2 rows. If there is only one row of tables, PVsyst will throw an error.
• The average axis tilt of the trackers in each tracker orientation. If the average axis tilt is too large, PVsyst will throw an error. You can change the threshold of the error in the advanced parameters.

[leesujin]

Currently, if the two-sided efficiency is applied, it is shown that only the Bifaciality factor is applied under the STC condition.
Now, we are receiving the test report of the double-sided module under BNPI conditions, can we apply BNPI conditions?

[Michele Oliosi]

BNPI conditions cannot be used as input in PVsyst. You could use the BNPI test report to re-evaluate the bifaciality factor. But per se the BNPI result will not be used in the simulation (in which irradiance and temperature conditions vary at every step).

To calculate the bifaciality factor the approach would be as follows. The basic equation is Pmeas(BNPI) = P(1000+phi * 135), and solve for phi (bifaciality factor). This could be solved by trial and error using the PAN file interface to evaluate P(irradiance, 25°C), but it will involve manual steps. Once you find which irradiance yields P(BNPI), you can easily find phi.