The conventional wisdom about solar panels — the ones that don’t move as the sun does, at least — is that they should face south, catching rays from the east in the morning and the west in the afternoon. But a new study says that’s wrong: Solar panels should simply face west. Gizmodo writes:

Researchers at the Pecan Street Research Institute did a study of homes with solar panels in Austin, Texas and found that when homeowners faced solar panels west they were able to generate 2% more electricity in a day. And they also generated more electricity in the afternoon, when power grids experience peak demand.

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And there’s another benefit to west-facing solar panels, too: They help save more money on electricity. Quartz:

[Q]uantifying the way that favoring late-day sunlight helps homeowners save money and utilities flatten out demand could lead to a simple but effective hack for the world’s solar installers: Simply re-orienting solar panels could shorten the amount of time it takes for them to pay for themselves.

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This is less than helpful advice for people who’ve got their panels locked down in some specific configuration on a slanted roof. But it’s good advice for anyone who’s still looking to install one — or can get up on their roof and re-orient the ones they’ve already got.