Residents of 10 Massachusetts communities will have one more month to go solar at a discount.

The Massachusetts Clean Energy Center and the Massachusetts Department of Energy, which are co-sponsoring the Solarize Massachusetts Program, announced last week that it is extending the deadline for families and businesses that want to install solar through the program until Oct. 31.

Solarize programs have gained popularity nationally. They’re designed to make solar more affordable by designating a limited number of suppliers and installers for the program so that the more people who sign up, the greater the economy of scale becomes and the deeper the discounts are to both home and business owners.

"Extending the deadline will give more people an opportunity to participate in the incredibly popular program," said MassCEC CEO Alicia Barton.

“For the third year in a row, we’re seeing residents and business owners flock to the Solarize Mass program, responding to the economic and environmental benefits solar electricity provide,” added Rick Sullivan, Energy and Environmental Affairs Secretary.

Program organizers say this round of Solarize has been incredibly popular and the deadline extension simply aims to include more people.

Ten cities are participating, including Bourne, Brookline, Carlisle, Chelmsford, Lee, Medford, Medway, Newton, Northampton and Williamstown. Between them all, there are 269 contracts for solar photovoltaic systemsfor a total of 1.9 megawatts.

Program organizers have little doubt the extra month will cause the contracted solar capacity to crest 2 megawatts of distributed generation.

“Extending the deadline will ensure everyone in these communities has the opportunity to take advantage of this program, which serves as a national model,” Barton added. “We’re pleased with the response so far and expect the number of signed contracts to increase dramatically during October.”

Installers participating in the program include Cotuit Solar, E2 Solar, Real Goods Solar, Second Generation Energy, SolarFlair and SunBug Solar. All have agreed to extend the contract deadline another month.

The Solarize Mass Program has been extremely popular and organizers say it has been successful in reducing costs for installed systems, as well as adding value for home and business owners. Massachusetts has competitive state tax rebates and other incentives for those who install solar and the state has quickly risen to prominence in the solar industry over the last two years. In fact, it is considered one of the fastest-growing solar markets in the country.