The 1,152 ground-mounted solar panels and 145-panel solar awning that will power the facility constitute a 450-kilowatt system capable of producing more than 542,061 kilowatt hours a year. Occupying three sections of the Weld Hill property, photovoltaic systems, or PV arrays, convert light directly into electricity and work in conjunction with a sophisticated energy storage system. Space below one array will be used as a pollinator meadow that supports wildlife. The benefits of the Arboretum solar installation are twofold, according to Friedman: harvesting the sun’s energy, and driving the general health of the local ecosystem.
The Weld Hill Solar Project is the third solar installation erected at the Arboretum as part of the University’s institutional commitment to sustainable development and fighting climate change. In 2016, the Arboretum installed its first solar panel array on the roof of the Hunnewell Building maintenance garage and a second on the Dana Greenhouse Facility Building. The Weld Hill project is Harvard’s second-largest solar installation, and it will increase the University’s solar energy capacity by nearly a third.
All three projects are funded by Harvard’s Green Revolving Fund and will reduce the Arboretum’s dependence on fossil fuel and nuclear-generated electricity. Over 25 years they could offset an estimated 1,144 metric tons of carbon dioxide equivalent, comparable to 1,250,650 pounds of coal burned, 2,649 barrels of oil consumed, or 145,874,092 smartphones charged.
Katie Lapp, Harvard’s executive vice president, emphasized the project’s impact.
“We as a University are continually reviewing practices to lower our carbon footprint and become a progressively sustainable institution,” she said. “The Arnold Arboretum is helping carry out that mission, not only through the advancement of scientific research through its living collections, but also as an important leader in sustainability efforts at Harvard.”
The project is employing the latest and most innovative solar technology available. Referred to as a “smart system” by Solworks Energy, the Boston-area solar and energy storage developer overseeing the installation, this system is so smart that it will not only monitor the building’s demand for electricity, but also jump ahead of it to use stored energy from a high-capacity battery array to reduce peak draw from the power grid — a critical feature for the Weld Hill laboratories, greenhouses, and plant growth chambers. The energy-storage battery array will mitigate use during high-demand periods when heavy energy consumption necessitates the use of less-efficient, carbon-emitting peaking power plants, which switch on when the grid is more stressed.