Cool roofs and solar PV panels
user-721843
| Posted in Energy Efficiency and Durability on
Does anyone know of studies on the effect of PV panels on the rooftop solar heat gain calculation? I imagine there’s some shading, some absorption and emittance from the dark colored panels, and overall a small effect due to surface area, but haven’t seen any studies…
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Replies
Brenden,
Here you go:
Solar panels help shade and insulate buildings, study shows
Solar PV Panel Shading, a New Consideration for ROI?
Thanks Martin!
Here's a quantifiable result of what happens: http://www.welserver.com/cgi-bin/plotdb/WEL0043/02InsideAtticDeltaToOutsideTemps-4Monthly.png . This chart shows the attic to outside temperature difference, on an average monthly basis.
In 2009, prior to adding solar panels, summer time highes were at 10 - 11°F (monthly avg of difference between attic and outside temp).
In March, 2010, 36 solar PV panels were placed on a South facing roof area (picture here: http://www.neukranz.com ). From the chart, it's clear to see that the summertime highs came down to 7 - 8°. In other words, the solar panels reduced the average attic to outside temp difference by about 3° in summer months.
While the 3° improvement is clear to see, I'm uncertain how to further quantify it into actual kWh reduced for heating and cooling.
(Carefully looking at the chart shows that this year (2012) the avg monthly attic to outside temp difference increased about 0.5°, accurately reflecting a substantial amount of blown in insulation added into the large attic in April.)
Hope this helps.