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<< Click to Display Table of Contents >> Bifacial system: 2-dimensional unlimited sheds |
  
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<< Click to Display Table of Contents >> Bifacial system: 2-dimensional unlimited sheds |
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For the basic principles of the bi-facial simulation, please click here.
Important Hypothesis
This simplified 2D model is only applicable to regular big systems in sheds. It neglects the edge effects, either at the extremities of the rows, and behind the last shed.
Therefore, it is not applicable, especially to experimental systems with few modules.
This basic model application treats - for the bifacial modeling - your installation as a generic "Unlimited sheds" configuration, i.e., with a single orientation, identical pitch between sheds, and without considering the shed's extremities. Note that it also does not differentiate between PV-sensitive areas and non-sensitive frames. Therefore you can use it:
➢either directly with a simple system defined with the "Unlimited sheds" option in the orientation option,
➢or with a 3D scene, provided that it is sufficiently big and regular for being approximated by the "Unlimited sheds" hypothesis.
| PVsyst will create an artificial "Unlimited sheds" system associated with your real PV system, just for the calculation of the bi-facial features during the simulation. |
| This "added" system should be similar to your basic 3D system defined in the calculation version. Therefore, this simplified model is not suited for complex systems that involve different orientations, different sub-fields, different pitches, etc. |
| Prior to the simulation, except the height above the ground, all parameters of this unlimited sheds object will be adjusted according to your real 3D system. The parameters defined in the bi-facial dialog are just here for a pedagogic analysis of the bifacial model in any conditions: they are not used in the simulation. |
2-dimensional calculation
The "unlimited sheds" hypothesis allows a simple analytic calculation of the shed's behavior, namely the mutual shading from shed to shed, considering one only direction.
This also simplifies the bi-facial calculations: we can consider just the ground points distribution along the azimuth line, and we can analyze their behavior in terms of the shed's configuration.
Therefore, this dialog is also a powerful tool for the understanding of the bifacial systems issues, and its configuration optimization.
For this calculation, we have to specify the sheds parameters (Plane Tilt/Azimuth, Pitch, shed width, height above the ground), as well as the Ground albedo.
You can play with these values as you like, and get evaluations of many parameters in diverse conditions. However at simulation time, the parameters as close as possible from the basic systems will be used.
The dialog shows:
| - | The basic parameters of the sheds disposition, |
| - | An evaluation of the ground irradiance for some specified dates (clear day), |
| - | An evaluation of the daily irradiance values for each month (clear day conditions), |
| - | A drawing - with animation - of the sheds and ground irradiance behaviors (beam, diffuse acceptance, ground re-emission, etc), |
| - | Some distributions of parameters, see below. |
Beam acceptance on ground: this highly varies according to the season. Here for November at latitude 43° North (instead of June just above):
Beam on Ground, and reflected : only a part of the illuminated ground re-emits to the collectors.
Diffuse acceptance: depends on the position of the ground point below the sheds.
