It’s one of the first big items on Denver’s climate change to-do list: switching more than 250 city-operated buildings to 100 percent renewable electricity, leading the way for the rest of the city and further boosting the market for clean power. It’s not a simple task for a fast-growing city of 716,000 — and it turns out a key piece of the puzzle lies on the plains of Adams County, in the unincorporated community of Watkins, population 653.
That’s where a growing array of small, privately owned solar farms is pumping renewable energy onto the electric grid on behalf of their customers, including the City and County of Denver. “Community solar gardens,” as they’re known, seek to fill the gap between rooftop or on-site solar panels and massive, “utility-scale” projects — and they’re a big part of how Denver plans to meet its goal of achieving 100 percent renewable power at municipal facilities by 2025.
Earlier this month, a Denver City Council committee gave preliminary approval for five new community solar contracts with Denver-based Oak Leaf Energy Partners, which operates community solar gardens across Colorado and three other states. That’s in addition to six agreements signed last year with Oak Leaf and two with community-solar firm SunShare in 2015. While a few of the projects are on the city’s northeastern edge, most are in Watkins, where cheap, undeveloped land is gradually being bought up by solar providers like Oak Leaf and SunShare.
Once approved, the new agreements will bring the city to an annual total of about 12.4 gigawatt-hours (GWh) of electricity from community solar projects. Along with the 11.1 GWh produced by the city’s subscription to “Renewable*Connect,” Xcel Energy’s utility-scale solar program, and the 1.5 GWh generated by rooftop solar installed at municipal facilities, that puts the city just over 20 percent of the way to its 2025 goal.
“At this point, it’s difficult to determine what the percentages will be for the various renewable options,” says Wade Balmer, a spokesperson for the city’s Department of General Services. “When it’s available, community solar will continue to be a focus in the future, along with subscribing to Xcel’s Renewable*Connect program.”
Launched in 2018, the Renewable*Connect program allows subscribers to purchase a share of the power generated by the utility’s new 50-megawatt (MW) solar farm near Deer Trail, roughly fifty miles east of Denver. But such utility-scale projects can take a long time to get off the ground, while many buildings aren’t capable of adding rooftop solar to generate their own power on site.
It’s in the vast middle between those two options that the community solar industry wants to do business — but hasn't always been allowed to by state law. Since they were first introduced a decade ago, Colorado has limited community solar gardens to 2 MW of generating capacity, along with placing a variety of other restrictions on their subscription models. Legislation passed earlier this year, though, is set to raise the limit to 10 MW by 2023, and industry advocates believe it’s poised to grow rapidly in Colorado and around the country.
The new law, the Community Solar Gardens Modernization Act, also removed a requirement that such projects be located within a given subscriber’s county, or the county directly adjacent — which is why one of the city contracts awaiting approval is for a subscription to a planned community solar garden in the Grand Junction suburb of Clifton, roughly 200 miles west of Denver.
Following the latest round of community solar subscriptions, Balmer says, “the next phase of the goal will be the implementation of performance contracting to help identify cost-effective energy improvements within municipal buildings and to help improve operating efficiency.”
Some of the city’s flagship facilities — including the City and County Building, the Wellington Webb Municipal Office Building and the Lindsey-Flanigan Courthouse — are now 100 percent powered by clean energy purchased through community solar gardens or the Renewable*Connect program, according to city data. But with a vast network of libraries, recreation centers, police and fire stations and more to account for, there’s still a lot of work to be done.
The 256 municipal buildings covered by Denver’s 2025 goal account for less than 2 percent of community-wide electricity usage, but Mayor Michael Hancock’s administration made the commitment to “lead by example” in its 2018 Climate Action Plan. Notably, the pledge doesn’t include Denver International Airport, which accounts for more energy usage than all other city buildings combined — though the airport has renewable-energy goals of its own and currently generates about 11.6 MW of power from its five on-site solar arrays.