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New Hampshire school goes to the top-in solar power

ReVision Energy has completed the installation of the largest rooftop solar array in the state of New Hampshire-at Dover High School-which on its own has increased the state's solar capacity by 1.5 percent.

By Robin Brunet

The unusually large scale of ReVision Energy's recent work creating and installing a solar roof on the new Dover High School and Career Technical Center in New Hampshire was one thing; the logistics of getting the job done efficiently was quite another.

For starters, work crews had to install 2,581 solar panels in sub-zero weather conditions.

"The project started in winter, and for those unfamiliar with New Hampshire, the temperature here can drop to -40 if you include wind chill," says James Hasselbeck, owner and director of operations at ReVision.

Marc Wiemer, project manager/estimator at Ayer Electric Inc. (ReVision's long-time electrical subcontractor and partner) adds, "Despite extensive pre-planning and a work crew operating at the top of their game, the cold was so bad that we had to abandon what was completed and return when the weather improved."

Despite the challenges, the job was finished in time for a ribbon-cutting ceremony in September 2019. It stands as the largest roof-mounted solar array in the state, generating over 1,000 megawatt-hours of electricity annually and forecast to meet 40 percent of the new facility's energy needs.

Dan Weeks, director of market development at ReVision, notes that the project was many years in development. "Plus our company had strong ties with the old Dover school-one of our master electricians used to teach there, and James Hasselbeck had been on its advisory board."

Weeks adds, "We've worked on over 8,000 projects since our inception in 2003, usually involving retrofits of old buildings. Dover provided us with several benefits due to it being a new build. But during the design stage of the new school, we had no inkling that the solar project would be so big." Indeed, the building committee that presided over the development of the new school initially planned to make the facility solar-ready, and this consideration was incorporated into the building's structural design.


Founded in Portland, Maine, ReVision is a full-service renewable energy contractor that has earned a reputation in its home state and in New Hampshire, Vermont, and Massachusetts for providing a full range of engineering, design, installation, and equipment services for homes, businesses, municipal buildings, and nonprofit organizations.

Prior to the Dover school project, ReVision had partnered with the City of Dover on the installation of rooftop solar arrays at the Children's Museum of New Hampshire and the adjacent Dover Indoor Pool. The company donated 103 solar panels for the installation, part of a 318-panel array at the museum and pool, which share a common electricity meter.

Hasselbeck credits the city for being "very forward thinking in making its energy goals happen," and Weeks adds that the Dover school moved from being solar-ready to having thousands of panels installed "due to the determination of various stakeholders, including the school committee. By the spring of 2018, RFP submissions were being considered under a public procurement process."

Dover's solar array was financed through a power purchase agreement, which enabled the city to purchase electricity at below-market rates and includes a purchase option that kicks in 10 years from now. Exercising the purchase option would enable the city to acquire the array at a significant discount and produce free solar energy for decades to come.

ReVision was no stranger to large installations. Although its work in the commercial sector often involves solar panels in the hundreds, it provided a 1.5-megawatt solar array (more than 4,500 panels) to power 13 percent of the energy needs for almost two million square feet of commercial and industrial space at a former Naval air base in Brunswick, Maine, and is currently developing some of the largest solar projects to ever be built in that state.

 Included in the Dover solar project were 2,581 REC Group N-Peak 210W solar panels, 1,432 SolarEdge solar optimizers, eight SolarEdge inverters, and a data acquisition system, along with a complete weather station that monitors wind, outside temperature, panel temperature, and sun irradiance

To prepare for the Dover project, a comprehensive profile of the school's 150,000 square foot roof was developed using drones and satellite imagery. Although the surface is flat, the roof resembles the letter "A" from above and contains many perimeter protrusions and odd angles.

"From this survey, we produced CAD drawings that we used to design our array," says Weeks.

ReVision decided early on to employ a lightweight and portable mounting and racking system from Ecolibrium Solar that would go a long way in ensuring that the massive installation would be completed in a timely fashion. "EcoFoot2+ is designed from a recycled plastic component and uses ballast cinder blocks as the base of the solar array, meaning we wouldn't have to penetrate the roof," says Weeks.

The EcoFoot2+ mounting and racking system has been successfully deployed on hundreds of commercial rooftops around the world due to its modular design that maximizes roof capacity and minimizes turnaround time. As Weeks points out, the hub of this ballasted mounting system is the base, whose optimized shape is lightweight and can be quickly positioned on most roofs. Pre-assembled clamps connect the modules to the rack base; deflectors bolt onto these clamps to help reduce wind loads on the racking system; and the solar panel mounting system provides a structurally rigid and electrically connected array.

To prepare for the Dover solar project, ReVision Energy developed a comprehensive profile of the school's 150,000 square foot roof using drones and satellite imagery. Although the surface is flat, the roof resembles the letter "A" from above and contains many perimeter protrusions and odd angles. 

The first step was for work crews to chalk out every row and pathway on Dover's Sika rubber membrane rooftop. "One unforeseen element we had to deal with was determining where the conduits would go," says Wiemer. "That was supposed to be figured out prior to site mobilization. But these things happen, and it ultimately wasn't too hard to deal with."

In January 2019, cranes hoisted palettes of panels and racking to pre-determined staging areas, and a small modular unit then moved the materials to their designated zones. "All of this activity had been carefully phased to deal with weather conditions and also to minimize any disturbance to school activities," says Hasselbeck.

But even the best laid plans of ReVision and Ayer Electric can go awry in a New Hampshire winter. "We worked in sub-zero conditions until February, when the cold combined with wind chill—exacerbated by the fact the school sits on an elevated area surrounded by clearcut—became so severe that we had to pull out and couldn't return until spring," Wiemer explained.

"However, a lot of work had been accomplished. We'd lifted about one third of the material onto the roof, and the inverters had been mounted at ground level; so when the weather got warmer and we returned, we were able to make up for lost time."


In total, about 20 IBEW Local 490 electricians instal-led the REC Group N-Peak 210W solar panels, 1,432 SolarEdge solar optimizers, eight SolarEdge inverters, and a data acquisition system along with a complete weather station that monitors wind, outside temperature, panel temperature, and sun irradiance.

Weeks notes that thanks to EcoFoot2+, installation "was a fairly straightforward matter of going row by row, with the work sequence in general being the slip sheets, ballast racking, panels attached to the racks, then cable attachment, and optimizers installed on every other panel."

The panels were pitched at 10 degrees to the south to mitigate snowfall weight and to provide slightly better solar gain. "The pitch also enabled Ayer crews to add wind guards to the ends of the rows instead of mechanical attachments," says Weeks.

Wiemer is equally enthusiastic about the benefits of EcoFoot2+. "It, along with the intense degree of preplanning that ReVision typically undertakes, really was the key to the success of this project," he says. "Once the block is down and the panel is installed, the system isn't going anywhere. It's a great solution for buildings in cold weather climates, and in our case, the total installation time was only four months."

Dover's solar array has a useful lifespan of 40 years, and the power generated is equivalent to offsetting 558 tons of carbon pollution each year; plus, it will increase the state's solar capacity by 1.5 percent and save Dover taxpayers more than $4 million long-term.

For the record, investor partner Kenyon Energy owns Dover's array and will sell the electricity to the city at a negotiated rate. Ongoing maintenance will be provided by Bay4 Energy, one of the leading solar service companies in the U.S.

A pleasing dividend of the project is that ReVision's agreement with the City of Dover includes an educational initiative aimed at teaching students how solar energy works and exposing them to the various functions involved in the engineering, electrical, and marketing aspects of the project. "Considering Dover is a technically-oriented high school focused on the trades, we were more than happy to support learning in this fashion," says Hasselbeck. "Supporting a local technical school provides a direct benefit to our local communities today, and it helps ReVision with future workforce requirements for future graduates, a true win-win."

As for Dover having the largest roof-mounted solar array in New Hampshire, Hasselbeck notes that it will likely inspire similar projects and cumulatively help to promote solar power as a sustainable energy source. "We've already seen interest in this project from other municipalities," he says. "We're very happy with the outcome, and while current legislative net metering limits in this state that would facilitate putting excess power generation back into the grid make it difficult for larger solar arrays to be built, we're optimistic that situation will change over time."