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Page added on November 17, 2013
Are Solar Panels Facing the Wrong Direction?
West-facing rooftop solar panels produced 49 percent more electricity during peak demand compared to south-facing panels, according to a new study from Pecan Street Research Institute.
The research is the first of its kind to evaluate the energy production of solar panels oriented in different directions. Pecan Street analyzed 50 homes in the Austin, Texas area. Some had only south-facing panels, others had west-facing panels, and some had both.
South-facing panels produced a 54 percent peak reduction overall, while west-facing solar PV panels produced a 65 percent peak reduction.
“There’s no other residential demand response tool generating 60 percent reductions,” said Brewster McCracken, CEO of Pecan Street. “Those are pretty extraordinary peak reductions.”
When the data was normalized for a 5.5-kilowatt system, the panels turned to the west generated nearly 50 percent more electricity during peak demand hours than did their southern-facing counterparts.
Homes with west-facing systems also produced slightly more electricity, with those panels producing 37 percent of total daily electricity use, compared to 35 percent for the south-facing panels.
During times of peak demand, which is defined as 3 p.m. to 7 p.m. in Texas’s ERCOT territory, 84 percent of electricity in west-facing systems was used in the home.
The information could help inform utility rebate programs for rooftop solar panels and demand response programs. Most homes currently have south-facing panels. For the research, Pecan Street paid a premium to participants to induce them to turn their panels westward. If more utilities were to move to dynamic pricing models, where power cost more during days of high peak demand, west-facing panels could potentially be more attractive to certain households with high peak loads.
The next round of research will also include information about the pitch of the roof. Panels on flat roofs tend to have higher rates of electricity generation, but most homes in the U.S. have pitched roofs, as did all of the participants in the first study. Pecan Street will also look beyond Austin in the next stage of the study. McCracken said there are plans to include homes in Colorado, Dallas and potentially California.
8 Comments on "Are Solar Panels Facing the Wrong Direction?"
BillT on Mon, 18th Nov 2013 1:04 am
Using one small area of the planet is NOT indicative of most places. For instance, a panel tilted 15 degrees and facing south is the best for my area here in the Philippines.
Facing west would be bad as most rain comes late in the day here and it would be cloudy in the above time period, on many days. This is true for most of the summer in PA also. Thunderstorms rarely happen early in the day.
mike on Mon, 18th Nov 2013 7:58 am
Plants do the best part of their photosynthesizing when the sun is in the west (late afternoon onwards) so I don’t see why someone hasn’t thought of this before. Those of us in the gardening world have known this for thousands of years.
Arthur on Mon, 18th Nov 2013 8:44 am
Good news for me, my roof is directed towards SWW. 🙂
Norm on Mon, 18th Nov 2013 12:28 pm
F-in Brilliant.
Maybe turn them over and point them at the ground. You see, then their power production, normalized, would be uniform all 24 hours.
I will guess, such a ‘study’ is a product of more welfare bums (‘principal investigator’ of a gubbamint research project). Good thing the gubbamint got infinite printed money, to pay for it all.
I would like to be awarded a $1.5 Million research grant, it will prove the best orientation is upside down, pointed at the ground.
ghung on Mon, 18th Nov 2013 2:40 pm
This is the problem of fixed arrays and being a slave to the demands of the grid. Of course, if you’re stuck with rooftop mounting, you’re stuck with whatever choices your roof allows. Seasonal demand is also a factor, as is BOS capacity.
Ground-mounted off-grid tracking arrays don’t have these issues. Just sayin’. That said, I have a couple of fixed arrays that I’m considering adding a couple of west facing panels to, to boost afternoon production,, because I can. Having a big flat roof, and no neighbors to complain, helps.
action on Tue, 19th Nov 2013 12:08 am
Yes, they are facing the wrong direction – they should be facing non-existence… yes, I think that would be best.
rollin on Tue, 19th Nov 2013 2:51 am
Adjusting the tilt twice a year gives a four percent gain. Using a tracking system gives a 29% gain over fixed angle panels.
Kenz300 on Tue, 19th Nov 2013 6:35 am
Solar keeps getting better every year……….