Solar gardens in the urban fabric

Denver’s vision for integrating solar into neighborhoods aims for more than just electrical generation

 by Allen Best

Denver is getting green roofs. Why not roof-top solar gardens, too?

That’s one of the potential outcomes of a program being pursued by the city. It recently was awarded a $1 million state grant to further its vision.

The vision is community solar gardens not just on roofs, but also on parking lots and vacant land, all owned by the city government.

In providing the land or other underlying infrastructure, the city hopes to dismantle one of the major challenges facing community solar developers in more dense urban settings: cutting a deal with the owner of the ground.

That explanation comes from Jonathan Rogers, renewable energy specialist in Denver’s Office of Climate Action, Sustainability, and Resiliency. Rogers joined the staff in April 2019 and quickly began working on the idea of using the assets of the city government to expand the penetration of distributed energy resources.

He assembled a rough list of 158 city rooftops, parking lots, and vacant land parcels owned by the city government. The spaces, whether on roofs or soil, were mostly of 10,000 square feet in size, as that is approximately the size needed to make economic sense for developing a community solar project. The parking lots are adjacent to recreation centers, libraries, and schools.

Denver’s program has several goals in mind. One is to create more local energy generation. The city government hopes to be able to generate 40% of the electricity it consumes.

A second goal is to provide electricity for lower-income residents.

The third and fourth goals overlap. The program hopes to see the solar gardens distributed across the urban fabric. This visibility helps provide connection to the broader goal of carbon reduction, says Rogers. A related motivation is to increase resiliency of its power supply to reduce the risk of power outages such as have occurred in California’s cities due to wildfires.

Have no illusions. Most of Denver’s power will come from elsewhere. That’s true for city residents and businesses. For municipal facilities, the program estimates 60% of power can be generated locally.

With this grant, Denver wants to build 4 megawatts of community solar generation. Bids were due last week. In the future, Denver’s programs aim for even more solar capacity.

The 158 locations identified for the community solar gardens may not all work out. Some roofs may not be able to withstand the added weight, for example. The final siting must accord with the capacity of the Xcel Energy transmission and distribution network. Among other considerations may be whether the location will be desireable for future electric vehicle charging needs.

Denver’s program should be viewed in the shifting energy landscape. One of those shifts was the Community Solar Gardens Modernization Act. The 2019 law adopted by Colorado increased the maximized allowed size of a community solar garden to 5 megawatts. Before it was 2 megawatts. With PUC authorization even 10 megawatts will be allowed beginning in 2023.

The $1 million grant is among $10 million allocated by the Colorado Department of Local Affairs Renewable and Clean Energy Challenge program for implementation of projects in the realm of renewable energy and energy efficiency. San Miguel County got $750,000 in the same funding, Gunnison and Gunnison County got $510,000, Fort Collins’ Aztlan Community Center $200,000, and Grand Junction’s BioCNG storage $540,000. Erie got $766,7094 for a hydropower project and Breckenridge $650,000 for its aspirations for a net-zero workforce housing project.

Denver’s project should also be seen as part of a partnership with Xcel Energy’s Energy Future collaborations. That program also keys in carbon reduction and maximized energy efficiency options along with the support of economic development.

Eight communities have signed MOUs with Xcel: Alamosa, Breckenridge, Denver, Lakewood, Louisville, Lone Tree, Nederland, and Westminster. Those MOUs are the forerunners for work plans.

Allen Best