North Star Solar is a 100 MW AC single-axis tracker photovoltaic (PV) project in Chisago County, Minnesota. Like many projects in the rapidly developing Midwest solar market, North Star was selected as a cost-effective way to meet the state’s 1.5% Solar Energy Standard set in place in 2007. With capacity to power approximately 20,000 homes, North Star is the largest solar facility in the Midwest.
The project was developed by Community Energy Solar as part of a vision to bring competitively priced solar energy to the Midwest. Swinerton Renewable Energy (SRE) was selected to provide Engineering, Procurement, and Construction services, with NEXTracker providing its unique “cold weather solution” tracking technology for over 400,000 PV modules.
According to Solar Power World, tracker projects can generate up to 25 percent more electricity than stationary or fixed-tilt projects due to their ability to “track” the progress of the sun across the sun and therefore maintain the optimal angle for maximum output. Because most tracker technology is designed for warmer climates with little to no snow, NEXTracker and SRE teamed up to develop a special design to conquer Minnesota’s coldest winter months.
NEXTracker’s self-powered control system (SPC), NX Horizon, is engineered to support ambient temperatures from -30C to +50C, which suits most site locations for solar power plants. For the tracker controller to perform in cold temperatures, the backup battery must be maintained at -30C or above to avoid irreversible degradation. The NEXTracker controller was designed with an insulating battery enclosure and resistive heater, which uses energy from the SPC solar panel to warm the battery during the day for optimal charging. At North Star, where temperatures dip below -30C, an additional heater must be operated overnight to prevent damage to the backup battery, requiring a wired power source.
As the Midwest continues to expand its solar footprint, the North Star solar power facility will continue to serve as a model for the region in both record-breaking size and its unique wired control system design. This cold weather tracking solution has been replicated by NEXTracker on other solar projects in New York, Vermont, Minnesota, and in multiple community solar projects in Wisconsin.
Visit www.nextracker.com to learn more about NEXTracker technology.