Clean energy: City’s new ground-mounted solar array nearly up and running
Kevin Moriarty/Missoula Current
As the sun shines bright with temperatures in the mid-90s, Ross Mollenhauer walks past a large ground-mounted solar array just off Reserve Street.
The project is nearly complete and will feature an array of 1,000 solar panels. Once live, it will generate 20% of the annual energy needs of the city's wastewater treatment plant - one of the city's largest energy consumers.
Mullenhauer, the city's engineering manager, expects the panels to be up and running sometime between October and December of this year. When it is, it will be the largest ground-mounted array in the county.
“It takes a lot of energy to pump water up and down the hills of Missoula.” said Mollenhauer. “The water department has a pretty big carbon footprint, and the wastewater department has a pretty big carbon footprint.”
When planning the installation of the solar system, the city had to work around rules that Northwestern Energy has in place. One being that any energy created by solar has to be consumed where it is created, without crossing property lines.
Secondly, Northwestern Energy only allows small solar systems under 50 kilowatts to sell extra energy back to the grid for credits to use later. The new solar array at the wastewater treatment plant is a 500-kilowatt system.
“It is a non-export system, which means we are not exporting power to the grid at any moment.” said Mollenhauer. “All the power we’re creating is being consumed by the treatment plant.”
Mollenhauer said they would have liked to produce more than 20% of the facility's energy needs but are somewhat limited by the current regulations Northwestern Energy has in place for the power grid. So, the array will operate completely “behind the meter.”
The original plan for the project was to install 1,200 panels, but with restrictions on exporting energy, any extra energy generated would have gone to waste.
The cost of the array stands at roughly $1 million. However, the city will not be paying that bill.
To cover the cost of the project, the city partnered with the financing company Ameresco. Ameresco is paying for the project and, in return, the city of Missoula agreed to purchase energy from them for the next 25 years at a rate that is only the slightest higher than what Northwestern would charge.
At that point, the city will own the solar system and the deeply discounted electricity it produces.
Ameresco specializes in this type of clean energy financing and makes a profit by receiving federal tax credits, something that isn’t available for a city government. In many ways, it turns out to be a win-win situation for Ameresco as well as the city of Missoula.
Missoula County was the first in Montana to finance a solar project this way when it installed the solar array on top of the detention center last fall. It's considering a similar project at the Missoula County Fairgrounds.
“What's neat about it is the city is getting 1,000 solar panels, we're meeting our energy goals, and we're paying the same price for the power.” said Mollenhauer.