Groton — Forty-by-65-inch solar panels line 800 buildings in a housing community here that serves mostly Navy families.

The panels were up and running in late November.    

The panels can generate slightly over 4 megawatts of solar power for the housing community of nine neighborhoods off Route 12 near Naval Submarine Base New London that is managed by Balfour Beatty Communities.

One megawatt can power an average of 164 homes per year, according to the Solar Industries Energy Association.

The entire community comprises 1,895 housing units, which were not all eligible for solar panel installation.

The panels transform the sun's energy and channel it through wires to an inverter, which converts it to electricity.

If the solar power system produces more power than needed, it feeds the excess power back into the electricity grid.

The solar project is the result of a power purchase agreement between solar power provider SolarCity and Navy Northeast Housing LLC, a public-private partnership between Balfour Beatty Communities and the Navy.

SolarCity completely financed and owns the system for its 20-year life, Aaron Gilmore, vice president of solar development for the company, said.

Balfour Beatty Communities will pay for the solar energy. And though it will be paying two bills — one from Groton Utilities and one from SolarCity — Gilmore said the company still should see energy savings.

The idea is that it will be buying less energy from Groton Utilities, and purchasing the energy from SolarCity at a lower rate, he said.

"More attractive than the savings today is the stabilizing rates for the next 20 years," Gilmore said, noting the length of agreement, which is fixed in price. "A utility (company) can't do that."

Utilities are included in residents' rents at Balfour Beatty Communities, so any savings realized by the company will go toward bettering the solar project either through additional investment or capital improvements, said Edward Lopes, project director and vice president of the Navy portfolio for the company.

The company is expecting to save 15 percent on overall energy consumption, Lopes said.

The main reason Balfour Beatty Communities chose to carry out the solar project was to help support the "Navy's objective of embracing renewable energy," Lopes said.

The Navy expects to meet President Barack Obama's goal of producing 1 gigawatt of renewable energy by 2015, with the overall goal of producing 50 percent of its energy from alternative sources by 2020.

j.bergman@theday.com