EnergyPlus: How to calculate incident solar radiation rate for shading surfaces

Does EnergyPlus calculate the solar radiation also for shading surfaces? My purpose is to obtain from EnergyPlus the totat amount of solar radiation that is reaching a PV panel (I classify it as a shading surface only and not as a PV panel because I need only the incident radiation in it). If I select as output "Surface Outside Face Incident Solar Radiation rate" in the CSV file are displayed only the radiations that refers to the surfaces of my building and not to the shading surfaces. Moreover, the calculated incident solar radiation does take into account the presence of other shading surfaces that can obscure the PV module?

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Jenny

asked 2018-02-06 08:29:05 -0500, updated 2018-02-06 15:56:07 -0500

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EnergyPlus probably calculates irradiance on shading surfaces if necessary, e.g. for reflections, but looks like it doesn't report it (I always assumed it did). So I tried the following: I made a dummy zone just for the PV with a roof surface in it, to be able to report irradiance (see attachment).

image description

e+ seems to be okay with this zone without a real zone volume. Now the irradiance on this surface can be reported. If Building:SolarDistribution is set to FullInteriorAndExterior or FullInteriorAndExteriorWithReflections shadowing calculations will take other shading elements into account. Also set the ShadowCalculation:Calculation Method to TmestepFrequency, in order to have higher time resolution shading calculations. By default it is only calculated monthly.

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adambgnr

answered 2018-02-06 10:52:00 -0500

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Hi Adam, thank you for your answer. I will try to do as you said. The problem is that I must classify the PV module as a shading surface on SketchUp because it has an effect on the heating and cooling needs of the building. At the same time, for some other calculations, I should consider the incident radiation on that surface in EnergyPlus.

Jenny (2018-02-06 15:32:22 -0500) edit

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"Surface Outside Face Incident Solar Radiation Rate per Area" will be reported for shading surface specified as PV generator, in addition to all building surfaces exposed to the sun.