Solar Energy Rising

Solar energy has come a long way in Massachusetts over the last decade. When BBR’s solar array was installed in 2008, the panels were an unusual sight. Now, rooftop solar arrays can be found in virtually every neighborhood in Greater Boston.

Benefits of solar

The most obvious benefit of solar energy is reduced carbon emissions and climate impact. A two-kilowatt rooftop system has the same environmental benefit of driving 7,000 fewer miles every year or planting one acre of trees, said Loie Hayes, a staff member of Mass Energy who conducted a workshop on solar options in November.

Producing electricity at the point where it is being used is more efficient than producing it in a remote location. When electricity travels from one place to another, power is lost during the process of transmission. This loss is eliminated with energy generated on site.

A network of power lines makes up what is known as the grid, an infrastructure that moves power from one location to another. If a home’s solar array produces more power than is needed at the moment—for example, a sunny day when no one is home—the excess electricity goes out into the grid for use elsewhere. If more power is needed in the home than the array is generating at that time, supplemental electricity flows in from the grid. The in-and-out flow of electricity is tracked by the utility through net metering. The homeowner is credited for excess electricity and charged for supplemental electricity, and billed for the difference, or “net.”

Another advantage of a solar array is that there is virtually no maintenance because there are no moving parts. Further, solar panels make it possible to switch to electric-powered transportation and heat systems—essential for reducing climate change, said Loie.

Options for installation

Power purchase agreements (PPAs) have become a popular option for homeowners who want to receive the benefits of solar, but who can’t afford the considerable expense of paying for an installation. In these arrangements, a third party investor pays for the array and continues to own it, essentially “renting” space on the homeowner’s roof. In return, the homeowner uses some or all of the electricity generated, paying the investor at a rate per kilowatt hour that is almost always lower than that charged by the local utility. The investor benefits financially through the sale of solar renewable energy certificates (SRECs; see related post).

The obvious advantages of a PPA for a homeowner is that no money is required up front, monthly electric bills decrease, and climate impact is reduced. However, they miss out on the long-term benefits of ownership, including the income from the SRECs. It can also be a challenge to choose an installer when many companies are competing for business, including some that use aggressive sales tactics.

For those who want the long-term benefits of owning their system, the Massachusetts Solar Loan program makes this a viable option for many more people. The loans have a low, fixed interest rate as well as extra incentives for people with lower household incomes: the program may pay a portion of their loan principal when the project is complete. Federal and state tax credits are also available to reduce the installation cost; federal tax credits have been approved through 2021. BBR owns its solar array, which paid for itself in electricity savings, incentives, and rebates in about five years.

A third option—community shared solar—is generating interest. A group of homeowners, businesses, and/or organizations come together and arrange for a solar array to be installed in one location with the benefits and costs shared by the group. The agreements can be complex, but when a project is completed, all parties benefit, including those whose homes or buildings couldn’t support a solar array of their own, due to orientation, for example.

Installation costs can also be reduced through “Solarize” group buying programs, such as Solarize Boston. Through this state initiative, a certain number of municipalities each year make a concentrated group purchase and work with prequalified installers. Buying the components in bulk brings down the cost by about 20%.

Prerequisites for a solar installation

To be a good candidate for a solar array, your house must have space on the roof that isn’t heavily shadowed by trees or surrounding buildings. Even the shadow cast by a chimney can affect performance. “If you have a tree, it’s benefiting your house with its cooling shade,” said Loie. “If you have to cut it down for another reason, fine, but don’t cut it just for the sake of solar.”

A sloped roof is best; solar panels can also be installed on a flat roof, but it is more costly because racking is needed to angle the panels. A south-facing roof is ideal. Southeastern and southwestern orientations are also workable. Due east and due west are more difficult because there are fewer hours of sun exposure each day, and more racking is needed. To see the solar potential of your home, visit

The roof of the home needs to be new or like new, and rafters need to be sound and able to bear the weight of the panels and racks. The solar contractor will need to access the attic space in order to evaluate the rafters. If the home is a condominium, you need legal rights to the roof.

You will need to install a two-way meter for net metering, and electrical service to the property must be adequate (at least 200 amp service). Wiring must also be up to par; knob and tube wiring does not meet the standard. If wiring is inadequate, financial assistance may be available from MassSave, which has grants for replacing knob and tube wiring to allow for insulation work.

Lastly, energy efficiency work on the home, including air sealing and insulation, should be completed before making the move to solar.

How to choose an installer

The Mass Clean Energy Center’s residential guide to solar lists all projects completed to date, cost, size of system, who made the modules, and the installer. Rather than sorting out the claims of salespeople, you can look at who has actually done the work of installing similar systems and contact them for estimates. This is also an opportunity to support a local business rather than a large out-of-state entity. As with any contractor, be sure to have everything in writing, and check past customer references before making a final decision.