Lucas Stephens

Ensuring Urban Inclusion in Illinois’ Community Solar Program

Solar energy is thriving in Illinois, bringing hundreds of megawatts of clean energy and over a thousand new jobs to the state this year alone.

Illinois’ community solar program is particularly booming. The program is designed to make solar energy more accessible to diverse communities. A single community solar project can provide power to multiple customers, including those who live in condos or apartments or otherwise cannot install solar on their own home. The law also requires the projects to be built “in diverse locations and…not concentrated in a few geographic areas” [20 ILCS 3855/1-75(c)(1)(K)]. However, that diversity has not yet materialized, so ELPC teamed up with Vote Solar to look into the data and see how the program could be improved.

We performed a geospatial analysis of this year’s approved community solar projects, and quickly recognized that urban areas were getting left behind. Most developers selected sites in rural areas, in an effort to minimize the costs and maximize the speed of acquiring land for the projects. While customers throughout the state will be able to subscribe to these rural projects, the urban and higher-density communities interested in more local community solar development wouldn’t see projects built nearby.

We urged the Illinois Power Agency (IPA) – the agency in charge of the community solar program – to address the uneven concentration of projects when it updated its renewables plan this fall. We further offered the agency a potential methodology to classify sites by their relative level of urbanism and prioritize underserved urban areas for development as a portion of future community solar projects. The IPA agreed that changes to the community program were needed to ensure the geographic diversity required by law, and went on to adapt portions of our offered methodology into the state’s long-term renewable energy plan, filed with the Illinois Commerce Commission in October (see p. 117). Here’s how we did it.

Classifying Urbanism

ELPC and Vote Solar based our analysis on the 2016 National Land Cover Database (NLCD), a definitive nationwide land cover dataset derived from satellite imagery and other data. It’s published at 30m resolution and classifies land into 16 categories established by the Multi-Resolution Land Characteristics consortium.

The NLCD is an important tool for federal, state, local, and nongovernmental organizations to determine spatial patterns and shape land management policy. It enables detailed measures of land use across large geographies. The NLCD classifies land into eight categories of developed and undeveloped land use. In order to distinguish urban from rural areas, we assigned a numeric value (1-4) to the four developed land-cover classes, according to the intensity of development, in ascending order (see Chart 1 & Map 1).

We then summed the development-values for each county subdivision (township/precinct) in Illinois and normalized the result by land area (a field of the county subdivision shapefile) to produce a unique Development-Density Score that serves as a measure of urbanism in each township/precinct. We then classified all townships/precincts into four classes based on their Development-Density score according to the goodness of variance fit (Jenks natural breaks classification system).

See the full data here (CSV file).

We used county subdivisions as the geographic units for this purpose, because they better circumscribe relative densities of development across Illinois than other geographic units (e.g. ZIP codes). Moreover, townships and precincts are drawn at a suitable scale (see Map 2). They are inclusive of both more and less densely developed areas, providing space and land for community solar projects even in the densest classes. That land and space would be limited if the geographic unit was smaller in scale (e.g., census tract), possibly inhibiting community solar project siting.

Prioritizing Underserved Urban Areas

In order to prioritize development in underserved urban areas, ELPC and Vote Solar offered an approach that paired our geospatial analysis with additional criteria intended to actively pull community solar projects into the urban fabric. We included these criteria out of a concern that, without them, the next iteration of community solar projects would simply play out as a microcosm of the first batch, with projects sited in the most rural corners of urban-classed townships and precincts. Each of the criteria selected was intended to disrupt that pattern by advancing projects with direct ties to the populace and to particular constituencies.

Illinois Power Agency Agrees

The Illinois Power Agency agreed with ELPC and Vote Solar that steps should be taken to ensure greater diversity and actually adopted portions of our offered methodology into a formula for ranking new, diverse community solar projects. The Agency’s formula (outlined below) would assign points to projects according to the development-density township/precinct classes we identified and other criteria related to the business models of projects and size of projects. Any new incentives for community solar projects would be divided between waitlisted community solar projects from the first round of the program and these new, diverse projects.

  • “Projects will first be sorted into four categories based on the development density of the townships in which they are located. The highest density class would get 3 points, the next class 2 points, the third class 1 point, and the lowest density class 0 points.
  • Projects developed in response to a site-specific request for proposal (RFP) issued by a municipality or community group would be awarded 1 point.
  • Projects that commit to only serve subscribers in the same township as the project would be awarded 1 point. If the township population is below 50,000, then subscribers could also be in adjacent townships to meet this commitment and receive this point.
  • Projects under 100 kW (AC) in size would be awarded 2 points. Projects between 100 and 500 kW (AC) in size would be awarded 1 point.”

The Agency’s Plan with this formula still has to be litigated by interested parties and approved by the Illinois Commerce Commission. It is possible that the formula and the approach to the future of the community solar program overall could evolve and – hopefully – improve through the litigation process. Either way, recognizing the need for a more diverse program is a great first step forward to increasing the diversity of the community solar Program.


ELPC is helping pave the way for solar energy, working with community organizations, industry experts, and policy makers to launch Illinois into the green economy. We fought for a modern, functional Renewable Portfolio Standard as part of the Future Energy Jobs Act (FEJA) of 2016, and we didn’t stop there. We’ve continued working with partners to see this legislation roll out effectively. Resultant projects include the development of large-scale solar farms, solar developments on brownfields, and solar developments in low-income and environmental justice communities through a program known as the Illinois Solar for All program, in addition to rooftop and community solar projects as part of the Illinois Shines program.

As with any policy, the devil is in the details. ELPC dives into the details to protect the consumer and help build fair programs for a strong green future. We felt it was important to examine the Illinois community solar program closely to ensure development reaches our densest geographies and most underserved communities. These new criteria will help bring the program into compliance with statutory requirements for geographic diversity within the community solar program. This is an important step forward for clean energy in Illinois and the Midwest more broadly.


Lucas Stephens,

Senior Research Analyst

Lucas Stephens is a senior research analyst at ELPC, working on a broad range on land-use issues and their impacts on air and water quality.

MORE FROM Lucas Stephens