Todd Olinsky-Paul, Project Director at Clean Energy Group, stands next to a sonnenBatterie unit. Photo courtesy of Clean Energy Group.
By George Harvey
Affordable rural rental housing has come to Waltham, Vermont. The McKnight Lane redevelopment project sits about a mile from downtown Vergennes, at a site that once was a mobile home park but had fallen into disuse. Development was done through a partnership of the Addison County Community Trust and Cathedral Square Corporation. McKnight Lane is particularly noteworthy because it is an affordable rental project operating at net-zero energy, meaning the units will generate more electricity than they use. And each is equipped with a battery, to provide backup power when the electric grid is down.
Getting to this goal required the dedication and expertise of a combination of organizations working somewhat out of public view. Green Mountain Power (GMP) provides electricity in the service area in which the redevelopment project was built. Having had experience with an extensive solar-powered microgrid in Rutland, GMP brought in the Clean Energy States Alliance (CESA), a non-profit organization in Montpelier, Vermont.
CESA operates nationwide with its sister group, the Clean Energy Group, to provide many types of support, ranging from information and education to an ability to call on the resources of a wide variety of other organizations. When GMP called CESA, the reason for bringing them in was stated directly. “We know you are interested in storage for resiliency for low income areas.” CESA, in turn, brought in Sandia National Laboratories and the Department of Energy’s (DOE’s) Office of Electricity.
Todd Olinsky-Paul, a project manager for CESA and CEG, stressed that the McKnight Lane project was unique. He said, “To our knowledge, this is the only rural low-income, net-zero energy rental project in the country. There are a few urban and suburban projects. There are a lot of homeowners who want the latest and greatest technology. Businesses like Walmart are doing this, but this is the only project we know of that provides net-zero energy for low-income renters at no extra cost.”
McKnight Lane has fourteen homes in seven duplexes. They were built by Vermod in Wilder, Vermont. Twelve units have two bedrooms and each of the other two units has three. The individual units are highly insulated and well air-sealed. Each unit has its own heat pump and ventilation system. Electric power is provided from a solar array on the roof of each duplex, all of which are net-metered. Each unit has six kilowatts of solar panels.
The McKnight Lane Redevelopment Project, in rural Waltham, VT at site of a former, defunct mobile home community. 6-kW solar array on the roof of two homes. Photo courtesy of VERMOD.
It is significant that each unit has its own six-kilowatt-hour sonnenBatterie, manufactured by sonnen and owned by GMP. They are charged by solar power, or by the grid when the sun does not shine, but they have a double function for power production. When demand is high, GMP can draw electric power from them, reducing the power bills of everyone in its service territory, as doing this reduces the cost of capacity and transmission services. (The overall price of these grid services is calculated based on the highest hours of demand). By bringing down its costs, GMP’s practice benefits all its ratepayers, whether they have solar panels or not. The battery systems also provide power to the McKnight Lane rental units when needed and can provide at least six hours of power when the grid is down.
CESA/CEG intends to use the McKnight Lane project as a model that could be studied and improved, and then replicated in other rural, low-income housing projects in Vermont and the region.
It is important for people, in general, who are interested in having their own solar panels to understand the importance of battery backup. In order to have power when the grid is down, it is necessary to be able operate as an off-grid system, and this nearly always requires batteries, in addition to on-site solar panels. Since the units at McKnight Lane have battery backup and their own panels, they can operate entirely without grid power.
Among the organizations involved in supporting the addition of batteries to the project were the High Meadows Fund and the Vermont Community Foundation Sustainable Future Fund. Additional funding came from Sandia and the DOE Office of Electricity. A large number of other organizations were involved in the project in various ways. More information can be found at the Addison County Community Trust web site at http://bit.ly/affordable-net-zero-housing.
Another project with CESA/CEG involvement is also worth mentioning. The Town of Sterling, Massachusetts has installed a 2-megawatt, 3.9-megawatt-hour battery system, which can supply up to twelve days of backup power to the town’s police and emergency services. This is the largest battery of its kind yet installed in New England. Like the McKnight Lane project, the battery was funded with help from the DOE’s Office of Electricity and Sandia National Laboratories.
CEG’s website is http://www.cleanegroup.org/.
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