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Rooftop vs. shading surface PV energy production

asked 2017-08-30 16:57:01 -0600

kmpiscopo's avatar

updated 2017-08-31 09:05:26 -0600

I am modeling a portfolio of buildings with on-site PV generation. Some of the buildings have rooftop PV, and others have ground-mount PV next to the building. I am modeling the rooftop PV using the "Add Rooftop PV" measure, and modeling the ground-mount PV by specifying a shading surface of the desired dimensions in Sketchup, and then using the "Add Simple PV to Specified Shading Surface" measure.

I have noticed drastically different electricity generation values from these two measures, so I performed an experiment on the same surface area, with the same parameters (18% cell efficiency, 75% of included surface area with PV) . I used the add Rooftop PV measure to a building with a rooftop area of 15,000 sqft, and the OpenStudio model shows an annual generation of 473,580 kWh/yr. When I specified a 15,000 sqft as a shading area, and applied "Add Simple PV to specified shading surface," the model shows generation of 70,464 kWh/yr.

Does anyone know what is going on here?

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Ah, herein lies the problem. It is light purple. Is there any easy way to flip the shading surface? I can only seem to rotate it within the same plane.

kmpiscopo's avatar kmpiscopo  ( 2017-08-30 17:58:00 -0600 )edit
1

Double click on the shading surface group then click on surface so it is selected. Then right click and choose 'reverse face'

David Goldwasser's avatar David Goldwasser  ( 2017-08-30 18:01:58 -0600 )edit

Thanks David. That works and solves my problem.

kmpiscopo's avatar kmpiscopo  ( 2017-08-30 19:06:43 -0600 )edit

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answered 2017-08-30 17:54:53 -0600

updated 2017-08-31 03:28:47 -0600

In the SketchUp Plugin is the shading surface facing the sun light purple or dark purple? The darker color is the outward normal for the surface and the side that PV panels are on.

If if it is light purple, Double click on the shading surface group then click on surface so it is selected. Then right click and choose 'reverse face'.

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@kmpiscopo, make sure you both upvote this answer (it was helpful), and mark it as accepted by clicking on the check mark next to it (it actually solved your problem). Thanks.

Julien Marrec's avatar Julien Marrec  ( 2017-08-31 03:29:24 -0600 )edit

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Asked: 2017-08-30 16:57:01 -0600

Seen: 530 times

Last updated: Aug 31 '17