If the PV is close to the roof and parallel to it, then you can use the IntegratedExteriorVentedCavity mode. See the example file called GeneratorswithPV.idf and the PV called “SNL Roof Paver PV”
EnergyPlus is not really set up for heat transfer surfaces that are not associated with a thermal zone.
From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Adam Scherba
Sent: Thursday, November 18, 2010 4:28 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] Accurately modeling PV temperature - day and night
Hello,
I am trying to use EnergyPlus to accurately model the diurnal temperature profile of a rooftop photovoltaic solar panel. I have created a shade surface on my roof, with the proper orientation and tilt angle. I also created a Generator:photovoltaic object which is assigned to this surface and uses the sandia performance model. This appears to model the daytime performance accurately, but does not allow for any nighttime cooling below ambient (due to long wave radiation to the night sky).
Is there a way to achieve this? It seems if I used the "integrated surface outside face" heat transfer integration mode it would allow for long wave cooling. However, my shade surface does not have any material properties, heat capacity, density, etc - and therefore would not be interacting with the PV energy balance. Is it possible to model a heat transfer surface that is detached from the building? Any examples that illustrate this would be greatly appreciated.
Thanks for your input.
-Adam
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