Investment in rooftop solar along the East Coast is soaring, in part, because of popular solarize programs.

Solarize programs concentrate a solar installer’s marketing and installation efforts in a single community to reduce overhead so community members can enjoy discounted solar installation prices. Cities can coordinate the events on their own, though many Eastern states are providing funding and marketing support for communities that decide to encourage residents to go solar.

Nearly 100 people attended a Solarize event in Avon, Conn. Earlier this month.

“It was a great workshop,” said Jill Appel with Astrum Solar, the installer selected to lead the Solarize Avon program. “It’s so energizing talking to be at these events because they’re all excited about it.”

Astrum Solar has participated in dozens of solarize events in Massachusetts, Connecticut and New York since 2011.

“We heard about these solarize programs happening on the West Coast,” Appel said. “We thought, ‘let’s pilot it here.’ We started Solarize Mass in Harvard and then decided to expand the program. Soon, we had a whole raft of communities sponsoring solarize programs.”

Today, Astrum Solar is one of 43 installers on Massachusetts’ approved list for solarize programs. The installers have participated in more than 20 solarize programs just in Massachusetts, Appel said.

“Then Connecticut picked up and they started sponsoring solarize programs and more recently New York has jumped on the bandwagon,” Appel said.

While Connecticut communities have sponsored solarize programs for the last couple years, Appel said she’s seeing even more interest this year.

Connecticut’s two major utilities got approval from the Public Utilities Regulatory Authority in November to raise rates. Connecticut Light & Power Co. will charge customers an average of $18 a month more and United Illuminating will charge an extra $35 per month, according to local news reports.

Those are substantial rate hikes that equate to about 24 percent for Avon residents, Appel said. It’s hard to say how much the rate increases are driving additional interest, she said, because interest is always high anyway when Astrum manages solarize programs.

“People are really inspired,” she said. “This is a town-sponsored event and they’re going to get lower prices.”

Financing and incentives are different in every state. In Massachusetts, the Solar Renewable Energy Credit market make the payback for new rooftop solar installations four or five years, Appel said.

“And these systems are going to last 25 to 30 years,” Appel said.

New York has a loan program that allows solar customers to begin saving money from day one, she said.

Solarize programs have been so successful because they are a common sense and grass roots approach to marketing.

“In general, they’re extraordinary programs that generate community interest,” Appel said. “It helps the sales process in terms of efficiency because the sales team isn’t traveling all around the state. It concentrates sales activity and the installers, too.”