Rooftop solar panels in North America face south. That’s just the way we do it. But California recently began to incentivize west-facing panels over south-facing solar.

New guidelines from the California Energy Commission call for a 15 percent higher rebates for west-facing solar arrays than for south-facing solar panels.

While solar panels collect more energy overall when they point toward the equator, that annual energy advantage isn’t as important as generating more clean energy in the early evening hours when Californians arrive home from work and turn on their air conditions, televisions and microwaves.

Facing rooftop solar panels toward the setting sun, can increase late-day energy production by as much as 50 percent, according to recent studies.

“Even though it is less energy on an annual basis, it’s more valuable from an air pollution perspective,” David Hochschild told the U-T San Diego.

California’s new rebate structure will be the first in the country to incentivize west-facing solar panels over south. But it probably won’t be the last.

Since Pecan Street Research released a study in November about west-facing solar panels, governments and solar industry leaders have increased the intensity of their discussions about which direction to point solar panels.

According to the Pecan Street study, south-facing systems produce more energy, but west-facing systems produce the most usable energy. About 42 percent of the electricity generated by south-facing solar panels is sent back to the grid. However, 75 percent of the electricity produced by west-facing panels is consumed on site.

That’s a good reason to encourage homeowners to orient their solar panels to the west.

In areas where the utility companies have variable electric rates for peak load hours and low-demand times of day, net metering incentives encourage homeowners to orient their panels to the west anyway. But many homeowners and even some solar installers don’t realize that those variable electric rates can make such a big difference depending on how panels are oriented.

Perhaps California’s new rebate for homebuilders that install west-facing solar panels will increase awareness and encourage more discussion and thought about which way to point panels in California and beyond.