You're Doing It All Wrong: Solar Panels Should Face West, Not South

HughPickens.com writes In the U.S., a new solar project is installed every 3.2 minutes and the number of cumulative installations now stands at more than 500,000. For years, homeowners who bought solar panels were advised to mount them on the roof facing south to capture the most solar energy over the course of the day. Now Matthew L. Wald writes in the NYT that panels should be pointed west so that peak power comes in the afternoon when the electricity is more valuable. In late afternoon, homeowners are more likely to watch TV, turn on the lights or run the dishwasher. Electricity prices are also higher at that period of peak demand. "The predominance of south-facing panels may reflect a severe misalignment in energy supply and demand," say the authors of the study, Barry Fischer and Ben Harack. Pointing panels to the west means that in the hour beginning at 5 p.m., they produce 55 percent of their peak output. But point them to the south to maximize total output, and when the electric grid needs it most, they are producing only 15 percent of peak. While some solar panel owners are paid time-of-use rates and are compensated by the utility in proportion to prices on the wholesale electric grid, many panel owners cannot take advantage of the higher value of electricity at peak hours because they are paid a flat rate, so the payment system creates an incentive for the homeowner to do the wrong thing. The California Energy Commission recently announced a bonus of up to $500 for new installations that point west. "We are hoping to squeeze more energy out of the afternoon daylight hours when electricity demand is highest," says David Hochschild, lead commissioner for the agency's renewable energy division, which will be administering the program. "By encouraging west-facing solar systems, we can better match our renewable supply with energy demand."

Comments

Re:But that isn't possible

[Mr D from 63]

An important aspect the author overlooks is that many residential customers prefer aesthetics over optimization, and therefore the panels are often mounted as closely in parallel with the plane of the roof as practical. It is one of the reasons residential based solar, on average, will always trail centrally based, larger scale solar in capacity factor. Centrally based solar installations are optimized for their location. (OTOH, residential power delivery suffers lower transmission/distribution line loss factors than centrally located, but that is a bit off topic)

The point regarding the incentives simply being for total production & not considering time is true, its one I’ve made here on /. before. Existing incentives drive installations that are optimal from a total MWH generation standpoint over those that lengthen the generation window. These incentives pretty much take tracking mechanisms out of play in favor of adding more panels for the same cost.

If the goal is clean air generation per $ invested, then generating less just to lengthen the window doesn’t make much sense. It is an energy cost increase on an already costly energy source. This guy is proposing that the government spend even more on incentives for installations that will produce less power overall. Given the existing infrastructure and the fact that other sources will continue to fill in the demand profile when renewables can’t, the proposed changes don’t seem to accomplish much other that increase cost.