For public housing authorities across Massachusetts, the sun does not have to shine on their rooftops to grant them the benefit ofsolarpower.

SunEdison has inked sixteen separate power-purchase agreements with public housing authorities across Massachusetts over the last year, all of which involve net metering credits for solar PV arrays installed elsewhere in the utility’s territory.

“We’ve very proud to partner with this many housing authorities,” said Steve Raeder, managing director of sales for SunEdison.

About three years ago, SunEdison won the solicitation to be the solar provider for PowerOptions, the largest energy-buying consortium in Massachusetts. PowerOptions provides energy supply to nonprofits as well as government entities.

More than 500 PowerOptions members can leverage the contract that has been hammered out with SunEdison, although there is some room to tailor it for each institution. SunEdison, and its financing partners, including its YieldCo, TerraForm Power, will own and operate the solar systems.

“Traditional, onsite rooftop solar is difficult,” said Raeder. “Virtual net metering is optimal to engage any physically constrained customer.”

The sixteen housing authorities in Massachusetts that have signed PPAs with SunEdison will receive net metering credits for electricity generated by more than ten solar systems installed across the state. The housing authorities, which span from New Bedford to Northampton, will collectively save an estimated $60 million in electricity costs over the next twenty years, and that is a conservative figure, said Raeder.

The next step for SunEdison is to try to replicate the work in Massachusetts with other housing authorities, but there are challenges. PowerOptions is a unique organization; many other housing authorities are not represented by a similar group that does the power purchasing.

In the case of the sixteen housing authorities, the savings will offset the state’s spending on electricity at the sites, but ideally, the Federal Housing Administration, which also provides funds for many large public housing complexes across the country, would also recognize long-term net metering contracts. “We’re looking for more definitive guidance,” said Raeder.

Another problem is finding the space for the systems. One of the largest potential markets for public housing, New York City, simply does not have a lot of spare land in the same load zones where public housing is located. Chicago could be another big market, but “Illinois needs an RPS fix before this becomes even worth chatting about,” added Raeder.

Reducing energy costs for public housing is a huge opportunity, but one that has been largely untapped, as it also is for the multi-family housing sector. An ACEEE study in 2013 found that in New York City, energy efficiency spending in multi-family housing accounted for just 2 percent of the total of all energy-efficiency program spending.

Even with some local challenges, “This is something we’d love to replicate elsewhere,” said Raeder. “These housing authorities stand to benefit, and it’s extremely valuable to them.”