Mass Innovations, From The Beacon, March 2019

In the midst of a development and redevelopment boom, Watertown officials decided the new construction presented an opportunity to boost solar power generation. A new ordinance now requires most new commercial buildings to install solar panels.

The compact town (4 square miles) has 231 solar arrays, but 217 of them are residential, according to Energy Manager Ed Lewis. Commercial arrays far outperform residential, 130kw per system versus 5kw per system, and so have a greater impact on greenhouse gas reduction.

“We have pretty good residential deployment [of solar], but commercial could be better, which was a big part of driving this ordinance,” Lewis said.

Watertown, a Green Community, has deployed solar panels on three municipal buildings that are well situated for the technology and will include solar on new school buildings.

“We have had a strong history of sustainability,” Lewis said. “We required a solar assessment in the past, so developers would have to do a solar feasibility study, but they didn’t have to do anything [beyond the assessment].”

The new solar mandate applies to new commercial buildings larger than 10,000 square feet; it does not apply to single-family homes or duplexes. The ordinance has exemptions for buildings that cannot take advantage of solar due to the structure or location. Parking garages, typically well-suited for solar, will be required to install it under the ordinance.

“We want to increase solar deployment in town,” Lewis said, “but we are emphasizing arrays that make sense.”
The Community Development and Planning Department worked on the ordinance for three years, and it faced a stringent legal review by town counsel before it was passed unanimously by the Town Council last November.

“We’re the first in the area to do this, but California, Texas and Florida have done some solar requirement ordinances,” Lewis said.

Lewis said the ordinance is an extension of requirements in the State Building Code, updated a year ago, that require a “solar zone” to be incorporated into the design of certain new commercial buildings.

Solar installation costs have dropped over the past 10 years, Lewis said, and the state and federal governments still offer healthy incentives. With production going up and pricing going down, these projects are more economically feasible than ever.

“You’ve got these nice new buildings coming up, so much of it is residential or mixed use, and these complexes are more sustainable and green friendly, which is a competitive advantage,” Lewis said.

For more information, contact Watertown Energy Manager Ed Lewis at 617-972-4250 or

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