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This article is part of a special��series from our��fall 2019 climate issue��on how you can level��up your��actions against climate change.��Visit��the full��Climate Action Guide here.��

Solar power is infectious. Among the biggest factors driving a homeowner’s decision to install rooftop panels isn’t politics or income—it’s whether the neighbors have them.��

Or so says research led by Yale economist Kenneth Gillingham. Once one array goes up in a neighborhood, it triggers a significant jump in nearby installations. In a , Gillingham and co-author Marcello Graziano found that a new solar system installed within the past six months��increased the number of additional installations within half a mile by .44 on average.

“It’s more than a clustering—it's a clustering that comes about because of peer interactions,” Gillingham says. “Word of mouth plays a really key role.��When people talk to others about the solar they put on their roof, they make it clear that putting solar on your roof is not a crazy idea: It’s something people do.”

This effect is stronger when solar panels are clearly visible to passersby. And if you really want your neighbors to catch solar fever, invite them over for a cookout or open house to see your system and further spread the word. Minnesota-based has seen firsthand that these home parties work. “The best way to sell a ­solar system is to have a ­customer do it,” he says.��

Studies reveal a similar neighbor-to-neighbor influence on other environmental behaviors, from buying alternative-fuel cars to using less energy. “It’s the new keeping up with the Joneses,” Blake says, “and that’s a great thing for our society and our communities.”

An Expert's Tips for Going Solar

IInstalling solar panels on your property is one of the boldest personal steps you can take to fight climate change. It can also save you serious money in the long run. We talked with Robert Blake, founder and CEO of Minneapolis-based installation company Solar Bear, about what you need to know to join the rooftop revolution.

Q: What’s the first step for someone who wants to install solar?

A: Get an energy-efficiency audit. They’re fairly inexpensive, and most energy companies help cover that cost. Before you make��an investment and��put��bunch of panels��on your roof, let’s��get an accurate energy load��profile for your home. So instead of getting 20 solar panels, maybe you only need 10 panels.

Q: What’s a common misconception you hear about solar power?

A: A lot of people think it can’t work in the Midwest, it can’t work in the North. But it actually works better here. When you’ve got more heat, it makes the parts work harder, and they break down. When you have weather like we have in Minnesota, it provides a cooling mechanism to our parts, and allows it to function more efficiently.

Q: Each installation is different, but can you give us a general feel for the cost of going solar?

A: The price has been coming down very, very sharply. Ten years ago, you’re paying maybe a thousand bucks for a solar panel. Now, you’re down to about 200 bucks. Before, it could take a week to two weeks to put up a solar job, and now you can do it in two to three days. It’s about a five-year payoff, and your panels are warrantied for 25 years. So you’ve got 20 years of free energy, so to speak.