Solar and battery system helps power Gosnold island

Since January, a new solar and lithium-ion battery microgrid is providing more than half of the electricity for the island village of Cuttyhunk during the peak summer months and is expected to cover 80 percent of the load during the rest of the year.

Like many other remote areas, the island – part of the town of Gosnold – was previously powered by a loud and costly diesel generator because it wasn’t possible to access power from the mainland.

“We had a hard time finding other villages in the U.S. that did this, although you’d find it with single homes,” said Gosnold Electric Light Commissioner Paul Elias. “This was an attempt to do this in a municipal context.”

A $2.15 million grant awarded in 2012 from the U.S. Department of Agriculture covered the majority of the cost. An additional $230,000 came from state support, other grants, and the town stabilization fund.

“We’d been planning this for quite some time and took a couple of years between getting the grant and starting construction,” Elias said.

The planning period worked to the town’s advantage, as the price of lithium-ion batteries dropped significantly.

After receiving the federal grant, the small island, with only about 15 year-round households, had to find the best piece of land to build the solar array. Available public land was less than ideal, however. Ultimately, the town leased a privately owned lot. A south-facing slope was chosen for sun exposure and because the panels would fit into a smaller space without shading each other.

Under the terms of the grant, the town was required to go through a series of archaeological and endangered species reviews before construction began last fall.

The town worked with Solar Design Associates in Harvard on design and to guide it through the process. The town went directly to the supplier to purchase the solar panels and panel racking, and brought in Princeton Power Systems to build the battery system.

The solar array is located about 2,000 feet from the “power house,” which contains the pair of lithium-ion batteries and the system’s “brain.” The storage capacity of the two batteries is 1,000 kilowatt hours. The diesel generators remain in place and automatically turn on as needed to meet peak load requirements and simultaneously charge the batteries.

“If you add solar with no storage, maybe you can make a 20 percent [cost] reduction,” Elias said, “but the diesel has to be idling in the background the whole time.”

The two batteries split the load and provide redundancy. The batteries are expected to last about 14 years. Elias said the town will start saving now for the eventual replacement cost.

A smaller system has been in place on neighboring Naushon Island for five years, but that solar microgrid uses lead acid batteries, which were the best choice at the time but are toxic and have a shorter lifespan.

“One of the things that has made renewables very difficult in New England is the aesthetics of the systems,” Elias said. “We did a lot of work to show people what it would look like, and made sure it wouldn’t stick out and be disruptive.”

One of the popular benefits of the new system, Elias said, has been a significant reduction in the noise created by the diesel generators running around the clock.