November 22, 2013
Contrary to some confused bloggers, solar panels produce the most electricity over the course of a year when pointed south, not west.
Tom Konrad, Contributor
A recent report from the Pecan Street Research Institute started a chain of articles with increasingly inaccurate conclusions.
The lemmings at Quartz, Gizmodo, and Grist, followed each other off the cliff of delusion saying that homeowners could produce more power by pointing their solar panels west, rather than south. The title of an article “Are Solar Panels Facing the Wrong Direction?” on Greentech Media seems to have started the lemmings rushing cliff-ward, even though the article itself got the facts right.
It simply ain’t so. The study found that the average house in a sample of 14 houses with west-facing solar arrays produced more electricity than the average of 24 houses with south facing arrays in Austin, Texas during the three months from June 1 to August 31st, 2013.
The study (which I obtained from Pecan Street) specifically says “Over the course of a full year, a south-facing orientation produces more total energy than other orientations.” In addition, Brewster McCracken, the president and CEO of Pecan Street, told me that he did not expect that the finding that the west facing arrays produced more energy even during that three month period was statistically significant, given the small sample size.
Point It West
That said, the study concluded that there were significant benefits to pointing solar panels west. While the highest annual electricity production will be produced with south facing panels, west-facing arrays are much better at reducing peak loads in climates with air-conditioning driven peak demand, such as Austin.
According to the study, a equal sized west facing system would have produced 49% more electricity during the peak demand hours of the summer months than a south facing system. Only 58% of electricity from south facing systems was used in the home, with 42 percent being sent back to the utility grid. Fully 75% of electricity from west facing systems was used in the home, with only 25% sent back to the grid (see charts.)
Because they help more to reduce peak load, and put less strain on electricity distribution systems, west-facing PV systems may have more value to the grid than do south-facing systems, despite producing less total energy over the course of a year.
More solar arrays should be pointed west, but not because they produce more power that way. They should be pointed west because, in many cases, the power they produce is more valuable. Utilities and governments should structure their incentives accordingly.
McCracken told me that some of the utilities in his area don’t even offer incentives for west facing solar arrays because “they don’t produce enough energy.” Those utilities are just as confused as the media lemmings who think you get more energy by pointing solar panels west.