Vertical system with bifacial panels > negative Global incident in collector plane

[Katinka89]

Hello,

we would like to simulate a plant as a vertical system with bifacial panels.

Our loss diagram looks like this:

We are wondering why we have a negative value for the global incidence in collector plane. Is it because we have a tilt of 90 degrees?

We would appreciate a brief explanation.

Thank you very much!

Janne

[Linda Thoren]

Hello,

The global incident in collector plane is the result of the transposition of the irradiance from horizontal to the plane of the array. A collector plane with 90 degrees tilt will receive less irradiance compared to a the horizontal and thus a negative value. 

Kind regards

[Katinka89]

Hello,

Thank you very much for your quick reply!

I have another question regarding the simulation of a vertical east-west system with bifacial modules:

As can be seen in the loss diagram above, it results in very high values for sky diffuse and beam effective on the rear side.

I suspect that this is due to the vertical system. Is the result of the energy output nevertheless correct?

Thank you very much!

[Linda Thoren]

Indeed the values for the sky diffuse and beam effective on the rear side are rather high. Other than the inclination of the panels, the pitch between the rows and the height above ground will have an impact the bifacial gain. In the analysis tool in the bifacial system definition window, you can evaluate the effect of changing these values as well as generate various graphs to better understand the impact of these parameters. See the youtube tutorial of how to use this tool in the link below:

   

[Katinka89]

Hello Linda,

thank you for your quick reply and the link to your tutorial, which is also very helpful.

Nevertheless, I wonder if our results could be correct.
We are planning a system with these parameters:

- vertical bifacial
- East West orientation
- height above ground: 0.8 m
- pitch: 10 m

and would like to compare the results with a standard south-facing system.

Thank you very much!

Janne

[Linda Thoren]

Hello,

Indeed you can make a second variant facing south and compare the results. Your simulation seems reasonable based on the information you have provided, though I of course cannot guarantee that it is all correct.   

Don't hesitate if you have further questions