Shining Bright: How a Connecticut Group Is Pinpointing Potential Parking Lot Solar Canopies

People's Action for Clean Energy (PACE) is helping local governments understand the possibilities for renewable energy, city by city.

As the US aims to meet global goals for reducing carbon emissions, it will require an outsized contribution from the power sector and a robust mix of sources, including solar, wind, geothermal, and hydroelectric energy, to supply the country's needs. State of Connecticut, for one, has set an ambitious target of achieving a zero-carbon electric grid by 2040, focusing on a wide range of renewables, with solar energy playing a major role. 

To help the state meet that goal, one organization—People's Action for Clean Energy (PACE)— focused on small-to-midsize solar projects by looking at land that has degraded from other uses. To that end, PACE has concentrated on large parking lots, evaluating the potential for installing solar canopies, city by city, across the entire state. 

While larger utility-scale projects are expected to be more cost-effective than smaller microgrids and rooftop solar arrays due to economies of scale, investments in smaller solar arrays closer to where energy is used can reduce the cost of operating the wider grid. California Public Utilities Commission, for example, is actively seeking the development of more distributed microgrids throughout the state. Not only are they less prone to starting wildfires, but they can also build greater resiliency against failures, which the larger regional and national grids are likely to experience.

For PACE, it’s also a matter of helping to protect natural resources by repurposing already paved land while making Connecticut greener.

Unlike sprawling solar farms, canopies can be sited on impervious surfaces, removing the need to disrupt scarce and valuable land.

As Judi Friedman, a former longtime president of PACE once said, we want "squeaky clean energy for Connecticut," and that sentiment continues to guide the current generation of leaders at PACE. 

PACE started in 1973 as a community-based organization that opposed a proposed nuclear plant in Middletown, Connecticut. Formed by faculty members at Wesleyan University and others from the community, the group's focus was advocating for safe and clean energy for the state.

Focus never wavered so the group ultimately developed its calculations of solar potential using industry-standard solar modeling tools after meeting with local solar installers. When a more recent proposal to construct a sprawling 26-gigawatt solar farm project in Simsbury, Connecticut, divided the town over fears it would change the agrarian landscape, it got the leaders of PACE thinking. PACE's president Mark Scully and others felt that there had to be some middle ground in the debate to promote solar energy but do so while respecting open space, forests, and farmlands.

Why degrade natural resources to build large-scale solar arrays when these can be installed atop already degraded land, the group contended.

PACE members began by researching various efforts and initiatives to promote solar canopies in the surrounding states and found several unique approaches to smaller-scale energy production in the Hudson Valley in New York as well as in Rhode Island. That gave them the confidence to turn their focus toward helping promote solar canopy projects in Connecticut.

PACE's journey to promoting small-scale solar efforts expanded with help from Kieren Rudge, a graduate student at the Yale School of the Environment, who is adept at using ArcGIS software. The first step was to investigate readily available data to use as part of the group's analysis, including what would become the group's foundation for information: data from the Connecticut Department of Energy and Environmental Protection (DEEP) and the University of Connecticut, which cataloged impervious surfaces statewide for stormwater runoff analysis.

Rudge cleaned up the impervious surfaces data—eliminating roads and other land areas that would not be suitable for solar canopies and focusing on those areas where it would be economically feasible to build them. That effort included identifying only those parking lots which had greater than 100 parking spaces or were roughly 30,000 square feet. Additionally, Rudge removed any unsuitable areas such as those that were shaded or zoned for industrial use and had heavy truck traffic. 

The next step was estimating the amount of solar generation that could be produced from each area.  While there are good metrics for rooftop solar arrays and large-scale solar projects, there's been a lack of reliable data relating to smaller solar canopies. So the group ultimately developed its calculations of solar potential by area after meeting with local solar installers and solar companies to discuss their experiences. 

PACE then developed a reasonably conservative algorithm, taking into account the potential layout of the solar canopies and other technical considerations. It allowed the group to convert the shape and area of land to its capacity for solar canopies, showing the potential energy generation for each area, including each parking lot.

The data was aggregated to help guide city-level policy. The results are viewable on a map showing all modeled canopies where PACE presents the current energy consumption together with the potential solar production levels and what percentage of total energy use could be provided by solar energy.

PACE was able to demonstrate that there were 8,416 viable sites with a projected combined capacity of 7,021 MW. The total resultant energy production across the state could reach an estimated 9,226 GWh, equivalent to 37.8 percent of the state's energy consumption or roughly enough to power 870,000 homes. PACE estimates that parking lot solar canopies, combined with what's expected from rooftop solar arrays, could ultimately produce 86 percent of current statewide energy consumption. 

For Scully, an important component of the analysis revealed that almost all the energy could be produced close to the source of its consumption, in the cities and towns throughout Connecticut. If the state incorporated solar canopies into the statewide Integrated Resources Plan and other statewide energy plans, Connecticut could avoid overreliance on large-scale production facilities that compete for space with vital natural resources, PACE has argued.

"These conflicts will invariably become more acute in the future. One way to avoid or minimize these inevitable conflicts is to site solar arrays on land that has already been degraded, including, notably, parking lots," Scully said.

In addition, PACE points to potential equity benefits that result from community solar canopies generating solar energy, based on the group's findings published in the peer-reviewed journal Solar Energy. Focusing on the demographic characteristics of each census tract and the potential use of solar energy within each, PACE found that solar canopies could produce 48.4 percent of current energy use across all census tracts that are categorized as low-income communities within the state. In the majority of nonwhite community census tracts, 58.5 percent of current energy use could be produced. For those tracts that are categorized as both low-income and majority nonwhite communities, canopies could produce 35.3 percent of the current energy use.

"Solar canopies that follow shared ownership models can be more accessible than installations that benefit property owners only," Rudge said.

The analysis fits in with PACE's broader mission of assisting municipalities to look holistically at their energy consumption, highlighting the major energy consumers within each city, broken down by category—whether residential, commercial, industrial, or transportation. The goal is to help cities understand their energy use and how they could get to a 100 percent renewable and efficient clean energy environment.

"To meet the state's goals, we will need solar arrays on residential and commercial rooftops, parking lots, as well as larger, utility-scale projects on brownfields, gravel pits, and other land parcels," Scully said.

For PACE, a big part of that effort must be based on community solar buy-in.

The same could be said for the rest of the country.

The National Renewable Energy Laboratory (NREL) estimates that with greater flexibility in the overall grid system, renewable energy derived from existing technology would be "more than adequate to supply 80 percent of the total US electricity generation in 2050 while meeting electricity demand on an hourly basis in every region of the country." 

The White House, working through the Department of the Interior, is seeking to significantly increase energy production on federally controlled lands and waters, with a commitment to deploy 30 GW of offshore wind energy by 2030 and a target goal of permitting at least 25 GW of onshore renewable energy by 2025. 

But that is a small down payment on what will ultimately need to be constructed. In 2021, solar and wind energy accounted for 228 gigawatts of power, which represented only 12 percent of total energy production in the US. Hydroelectric contributed another 6 percent, which together with a few other renewable sources brought the total to just under 20 percent. 

The task of achieving a reduced carbon future will require investments of transformational proportions at the national level, including the kinds of transformation PACE has helped to identify.