Interconnection bottleneck threatens community solar success in Illinois

Community solar has thrived in Illinois, thanks to clean-energy laws passed by state legislators in 2016 and 2021. Now, though, one major utility’s especially slow process for reviewing applications could jeopardize further progress. Developers stuck in the interconnection queue may not be able to access key federal tax credits that were sent to an early grave by the GOP’s One Big Beautiful Bill Act.

The beauty of community solar is that it allows anyone, even those who can’t put photovoltaic panels on their own properties, to access solar energy via subscriptions to a larger array sited elsewhere. Until congressional Republicans passed their budget law this summer, the companies building community solar could tap federal tax credits into the 2030s; now, projects must begin construction by July 2026 or be placed in service by the end of 2027 to qualify.

Before any power-generating project can connect to the grid, it needs to undergo a lengthy review. Utilities must determine the project’s viability and the cost of grid upgrades that it might require, which the developer usually pays for and needs to know ahead of time to secure financing. Though the process is notorious for taking too long, the actual length of time a proposal spends in this interconnection queue can vary greatly depending on the utility.

Advocates are calling out Ameren, which serves central and southern Illinois, for taking longer than the norm. One major reason is that the utility only studies community solar applications one at a time. At that rate, it takes years or even decades for proposals to be reviewed and ready for construction.

By contrast, ComEd, the utility that serves northern Illinois, reviews multiple project proposals concurrently and ​“typically performs hundreds of studies every month,” according to the ComEd team that specializes in interconnection and distributed energy resources.

Ameren currently has over 1,700 projects pending review in its interconnection queue, the vast majority of which are community solar, according to Ameren spokesperson Marcelyn Love.

The utility is moving toward studying proposals concurrently, like ComEd does, but the policy won’t be fully in place until January 2027, said Love. That’s too late for projects depending on the federal tax credit to make their finances work.

“I think we’ll see a lot of projects that can’t meet these deadlines and just fall off,” said Jessica Collingsworth, central policy director for Nexamp, a community solar developer with headquarters in Chicago and Boston. ​“Every developer is trying to start construction on as much as possible.”

How can utilities speed up the interconnection queue?

Illinois currently ranks among the top five states for community solar capacity. Illinois lawmakers kick-started this development in 2016, when they created a state program now called Illinois Shines to incentivize development of the shared arrays.

About 768 megawatts of community solar are already operating statewide, according to a report by consultancy Wood Mackenzie and the Solar Energy Industries Association, a trade group. But far more proposals are pending, meaning Ameren and ComEd have needed to quickly figure out how to add increasing amounts of community solar to their grids.

ComEd now has about 200 community solar projects totaling more than 430 MW of generation in its territory, according to utility spokesperson David O’Dowd. In 2025 so far, the utility has received 442 requests for new community solar projects. It is dealing with about 750 pending applications in all, including around 80 that have interconnection agreements but are awaiting a customer signature, O’Dowd said.

Even with the glut of applications, ComEd said it has managed to complete interconnection studies and agreements in a timely fashion, in part because it studies projects concurrently.

Developers agree with that assessment. Nexamp, for example, ​“has experience in over a dozen markets and finds concurrent studies to be the fastest way to get local solar to the grid,” Collingsworth said. The firm has 31 community solar projects operating in ComEd territory and a number of proposals pending in Ameren territory.

“We need certainty around interconnection costs before we can feel confident beginning construction on projects,” said Collingsworth. ​“Anything that delays getting that certainty is a problem we need to solve quickly.”

Love said that Ameren is increasing its ​“internal and contractor resources” to be able to do multiple studies at the same time — in other words, the utility is bringing on more experts to review proposals.

“These improvements have already helped us advance 20 applications that were second in line, allowing us to both test out the concurrent study process and get more applicants information about their projects,” she said.