Just to the left of Cooper’s cubby in a preschool classroom on Eden Prairie’s Lower Campus is a game closet. Behind a locked door in the closet is a nearly vertical set of steps leading to the building’s roof.
What Cooper may not know is that at the top of those steps is a miniature power plant consisting of 125 solar panels stretching across the roof above he and his classmates.
The array is one of 20 on eight Eden Prairie School district buildings that generate just over two megawatts of electricity annually – enough to power 258 homes for a year, according to Jason Mutzenberger, the district’s executive director of business services.
Eden Prairie Schools has been in the solar power business since 2015 when it made the decision to invest in two community solar gardens in Wright and Dakota counties. Shortly after that, Mutzenberger nudged the district toward the rooftop arrays based on his experience at another school district.
Mutzenberger, who joined Eden Prairie Schools in 2014, initially saw the financial benefits. “Since then, it has become as much about the environmental impact of sustainable energy,” he said.
The solar panel arrays installed on the roofs of Eden Prairie school buildings has the same impact on carbon dioxide (CO2) emissions as planting 15,000 trees and removing 330 cars from the roads, Mutzenberger said.
They also generate enough power to charge a smart phone 194 million times.
More importantly, the district’s investment in rooftop solar and solar gardens produce the equivalent of 80% of the district’s annual electricity usage, Mutzenberger said. The district expects to save $4.3 million in energy costs over 25 years from the rooftop arrays and another $4 million from the solar gardens.
Utilities are the third largest budget item the school faces, behind salaries and benefits, Mutzenberger said.
Rooftop and solar gardens
The first panels were installed at Cedar Ridge Elementary, Oak Point/Eagle Heights and Prairie View Elementary in 2017. Now there are two arrays on each district building, except the transportation building. Four more are being installed in 2021 – another at Cedar Ridge and Oak Point that will be completed by June, and others at Central Middle School (CMS) and Eden Prairie High School (EPHS) to be completed by the end of the year.
The district is able to take advantage of state and federal subsidies to avoid paying upfront costs for rooftop solar panels, Mutzenberger said. Annual energy production pays for installation and maintenance over the course of contracts that run from 13 to 20 years.
iDeal Energies of Minneapolis installs and maintains the rooftop solar arrays on school buildings. The panels are warranted for 25 years and are expected to last 40 years, Mutzenberger said.
The district’s solar gardens also went online in 2017. It owns four megawatts of the electricity produced at three locations, including 20% of two solar gardens in Dakota County and 40% of another in Wright County near Watertown. Each of the gardens generate five megawatts of electricity each year.
Chicago-based SoCore Energy operates the Watertown site and Ecoplexus, with offices in North Carolina, Texas, California and several international locations, operates the Dakota County facilities.
Will the district run out of roofs?
“Kyle would say yes,” Mutzenberger said, laughing, referring to Kyle Fisher, director of facility safety and grounds.
Fisher said that the number of arrays that can be added to district buildings depends on the condition of roofs and where they are in their life spans. “We need to think critically about where we are placing our solar arrays,” he said. Adding arrays in conjunction with roof replacements and other major maintenance projects reduces the disruption to existing power generation, he added.
When roofs do run out, additional options for solar arrays include parking lot canopies and ground installations, similar to the one the City of Eden Prairie has installed at its water plant at Highway 5 and Mitchell Road.
Saving versus generating
Electricity generated on school roofs doesn’t power the plugs in each building. Instead, it goes back to the vast power grid and is credited to the utility bill at each site, which are metered separately.
By law, the district is limited to generating up to 120% of its electrical needs using solar power. The district’s goal is to produce 100%, Mutzenberger said.
“Can we get there?” he asked. “I’m not sure. We haven’t run the calculations to see if we have enough rooftop available to get to the 100%.”
That’s why saving energy will play an important part in achieving that 100% goal, Fisher said. To that end, the district is working on several fronts.
- The district uses B3 Benchmark, a free program offered by the State of Minnesota that tracks utility data. The program helps monitor water and natural gas use, as well as electricity.
- The district has switched lighting from old fluorescent technology to more efficient T8 bulbs and are moving toward LED lighting.
- Automation systems help manage school building climates, start-up times for heating and cooling, hallway lighting and other issues. School thermostats are set at 70 degrees in winter and 75 degrees in summer.
- To avoid paying higher peak demand utility rates, the district starts up large heating and air conditioning units in 15-minute increments rather than all at once.
- Six Maintenance Operations Coordinators (MOCs) work for Fisher managing individual buildings. “They know their buildings inside and out,” he said, and even maintain a friendly competition among themselves to see who can save the most energy,
- Energy audits are conducted by contractors, rotating between buildings each year to identify potential energy savings.
- The district has initiated meetings with Xcel Energy to discuss the feasibility of purchasing electric school buses, Mutzenberger said. “We will weigh the significantly higher cost versus the benefit to the community,” he said.
- Charging stations for electric vehicles are being installed in the CMS parking lot for use by the school’s staff as part of its ongoing construction project.
Currently, 60 of Minnesota’s 366 school districts generate solar power, according to Peter Lindstrom, manager of public affairs and community engagement at Clean Energy Resource Teams (CERTS). CERTS, a public/private partnership, provides schools with technical assistance, tools for site selection and other resources free of charge.
CERTS focuses on the financial, educational, environmental and community aspects of solar energy, Lindstrom said.
The cost of solar panels has dropped 65% over the last decade and schools avoid upfront investment and ongoing maintenance through third-party ownership, he said.
Real-world solar data monitoring has become an element of Science, Technology, Engineering and Math (STEM) curriculum in districts producing solar power. An EPHS AP physics class has used metering data to track real-world performance, Mutzenberger said.
Solar schools offset an estimated 1 million metric tons of carbon dioxide annually – equivalent to greenhouse gas emissions from nearly 221,000 cars, Lindstrom added.
A bill currently working its way through the Minnesota Legislature would appropriate $16 million for grants to school districts to build on-site solar. At least half of the grants would go to districts with at least half of their students enrolled in free or reduced-lunch programs, according to the Minnesota Solar Energy Industry Association.
Eden Prairie Schools also partners with the City of Eden Prairie, Hennepin County, and Xcel Energy as Partners in Energy. They meet periodically to discuss ways the entities can work together on a number of sustainability issues, including utilities, waste reduction, food composting and others, Fisher said.
“We would like to be part of building a more comprehensive plan to achieve sustainability,” Mutzenberger said.