HI, XiangJing
Time really flies. I think, it was over a year ago when I first saw your name in this group.
I thought solar collectors and PV panels are all simulated as detached shades to a building.
If the bottom face is part of the building, the ventilation to that surface is changed to a building zone instead of the outdoor air. Is this what you meant by integration?
As PV panels are enclosed in a separate unit, I have not look at the EPlus model constructions for this component.
If it is mounted on top of a eco-roof with soil and grass, then it would be a different situation. The eco-roof will only see a shade, if not in contact. The PV panel characteristics may not change, if it is not temperature dependent. (IR dependent from below.)
If the panel is in contact with the soil, there is a surface temperature program in EPlus for calculating the temperature below a building and on the ground surface.
Because the soil layer is not very thick, it would also be affected by the zone temperature below, rather than the deep ground temperature.
My guess is that the edge of the panel up to three times the soil thickness would follow the surface temperature of the soil. The inside central area would follow the building zone temperature below with the conduction model.
If the space between the panel and the roof is small, the VentedCavity model with AFN will probably give you an added degree of accuracy in the temperature value of the panel. Then, the wind speed and direction need also be provided in the simulation.
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Do you place the PV panel in the green roof mean adding another layer of glass. If it is, would it be the same as simply changing the spectrum properties of the PV panel glass, like a internal window.
I have no experience working with PV cells. I assume it is using the shortwave radiation rather than the IR waves. Therefore, the transmission properties of the glass used in the cover and green house are more relevant. The material glazing object in EPlus does allow you to enter the costumed values, as transmittance and wavelength, etc.
MaterialProperty:GlazingSpectralData
has a field for 450 sets of [wavelength, transmittance, front reflectance, back reflectance]
for wavelengths covering the solar spectrum (from about 0.25 to 2.5 microns).
I have never used this myself, but have seen this used in some examples.
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: geshen516@xxxxxxxxx
Date: Thu, 27 Jan 2011 01:47:52 +0000
Subject: [EnergyPlus_Support] The capability of investigating integration between PV panel and Green Roof
Is there any possibility to investigate the impact of green roof on the detached PV cell temperature in EnergyPlus?
According to my understanding, the detached PV can be simulated by VentedCavity model; however, the VentedCavity is a simple model for natural ventilation. When the VentedCavity model is working together with EcoRoof, the integration between them will not be considered.
Thanks for your time and kind advice.
Best Regards
ZHANG Xiangjing
Solar Energy Research Institute of Singapore, NUS
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