The Grundy County solar farm lawsuit, Equity Solar Illinois v. County of Grundy, ended in March 2026 with the Illinois Third District Appellate Court ordering the county to issue special use permits for two commercial solar projects it had voted to reject. The court held that once a solar developer meets the requirements set out in Illinois’s 2023 siting law, county approval is mandatory, not discretionary. A conflicting ruling from the Fourth District three months later has pushed the underlying question — how much authority counties still have over solar siting — toward the Illinois Supreme Court, where Grundy County’s petition for leave to appeal is pending.1AFS Law. Illinois Appellate Courts Split on County Authority for Solar Siting
What the Lawsuit Was About
In September 2023, two Delaware solar companies, USS Middle Solar and USS Saratoga Solar, applied for special use permits to build 5-megawatt solar facilities on roughly 35 acres each of agricultural land in unincorporated Grundy County. They were joined in the later litigation by Equity Solar Illinois.2WCSJ News. Grundy Co. Board Approves Two Solar Farm Projects, Denies Two Others
The applications went through the normal county review. The Zoning Board of Appeals recommended denial after a public hearing in December 2023, the Land Use Committee agreed, and in February 2024 the full county board voted unanimously to reject both permits. The county’s stated reasons were incompatibility with surrounding properties, unsuitability for the area’s future development, lack of county benefit, and safety concerns. The City of Morris had also raised objections tied to possible future airport expansion, speculative commercial development, and battery storage worries. None of the reasons identified a specific requirement in state law or the county’s own ordinance that the developers had failed to meet.3FindLaw. Equity Solar Illinois v. County of Grundy
The developers sued in May 2024, filing a mandamus action in Grundy County Circuit Court. Mandamus is a narrow remedy: it asks a court to compel a government body to perform a duty the law gives it no discretion to refuse. The developers argued they had met every requirement, so the county had no legal choice but to issue the permits. In May 2025, the circuit court agreed and ordered the county to approve both applications. The Third District Appellate Court affirmed that order in March 2026.4Illinois Courts. Equity Solar Illinois v. County of Grundy, 2026 IL App (3d) 250289
Why the Court Ruled Against the County
The decision turned on Public Act 102-1123, the 2023 amendments to the Illinois Counties Code that set statewide standards for siting commercial solar and wind facilities. The statute barred non-home-rule counties from imposing standards more restrictive than those in the law and stated that once an applicant met all applicable requirements, the special use permit “shall be approved.”5Illinois General Assembly. 55 ILCS 5/5-12020
The appellate court read that language as a clear legislative intent to restrict the county’s traditional discretion over solar land use. The word “shall,” it found, created a nondiscretionary duty. Counties kept authority to set certain conditions, including setbacks, vegetative screening, and decommissioning, but they could not stack on additional requirements or deny a compliant application based on general land-use objections.4Illinois Courts. Equity Solar Illinois v. County of Grundy, 2026 IL App (3d) 250289
Two parts of the ruling matter for how similar disputes will play out:
- Standard special-use tests do not apply. The court rejected the county’s attempt to invoke the broader factors Illinois courts typically weigh when reviewing special use permits. The legislature had created a narrower, specific framework for solar siting that displaced those tests.
- Speculative objections do not count. Concerns about a neighboring city’s possible future expansion, or subjective incompatibility with nearby properties, were not valid grounds for denial under the statute.
Because Grundy County produced no evidence that the developers failed any enumerated requirement, the court found no legal basis for the denials.
The Appellate Split and the Supreme Court Appeal
The Grundy ruling did not settle the question statewide. On June 2, 2026, the Fourth District Appellate Court decided Tate Road Solar 1, LLC v. County of Winnebago the opposite way. That court held the 2023 amendments do not strip counties of all discretion, that counties may consider subjective factors written into their own ordinances, and that mandamus is not an appropriate remedy to force a permit to issue.6FindLaw. Tate Road Solar 1, LLC v. County of Winnebago
Neither decision binds courts outside its own district. For now, a solar developer’s prospects can depend on which appellate district the project sits in. Grundy County State’s Attorney Russ Baker has filed a petition for leave to appeal to the Illinois Supreme Court, which remains pending. Baker said the county is not opposed to solar outright: “We’re not trying to be anti-solar, but we’re also trying not to give it away.” He noted that Grundy and Winnebago are the only two Illinois counties actively contesting the state’s preemption of local solar siting authority.7Shaw Local. Grundy County Intends to Appeal Appellate Court’s Ruling on Solar Panels The direct conflict between the districts is the kind of split the Illinois Supreme Court typically takes up.1AFS Law. Illinois Appellate Courts Split on County Authority for Solar Siting
Grundy County’s New Solar Ordinance
While pursuing the appeal, Grundy County moved to rebuild its legal footing through a tougher local ordinance. On June 9, 2026, the county board approved a new solar ordinance with only one dissenting vote. The ordinance requires all state-mandated application materials to be submitted in final form before a hearing can be scheduled, and it adds sound, avian, wildlife, and glare modeling, soil borings, and historic preservation studies to the application package. It raises insurance limits, requires irrevocable financial assurances for decommissioning, and requires developers to disclose material sourcing information to show compliance with the Uyghur Forced Labor Prevention Act. Baker described the ordinance as an effort to strengthen the county’s position while staying within state law.7Shaw Local. Grundy County Intends to Appeal Appellate Court’s Ruling on Solar Panels
Whether that package will survive the same statutory test the Third District applied, which bars standards more restrictive than those in state law, is the next fight waiting to happen.
How the Ruling Fits the Rest of Grundy County’s Solar Docket
The Equity Solar case is the highest-profile solar dispute in Grundy County, but not the only one. The county’s active petition records list roughly 15 to 20 solar projects in various stages, from small community installations to the 960-acre, 116-megawatt Buffalo Solar Farm developed by RWE.8Grundy County. Active Petitions RWE’s project, initially denied in September 2023, moved forward after a March 2024 settlement that added setbacks and landscaping.9Shaw Local. Grundy County Introduces Guidelines for Permitting Solar Farms
Other projects have followed different paths. In June 2025, the county board approved ECA Solar’s 6.16-megawatt Gore Road project along Interstate 80 in Saratoga Township. The City of Morris sued, and the Grundy County Circuit Court dismissed the suit with prejudice in December 2025.10PRNewswire. ECA Solar Welcomes Court’s Decision Allowing Advancement of Solar Development Project In September 2025, the board unanimously rejected a 2-megawatt Brisbin Road project, siding with the City of Morris and local economic development officials who argued the interchange land was better suited for industrial use.11Shaw Local. Grundy County Board Issues Rejection on Brisbin Solar Project
If the Third District’s reasoning in Equity Solar stands, denials of the kind that stopped the two USS projects, and arguably the Brisbin project, will be hard for Grundy County to defend going forward. If the Illinois Supreme Court takes the appeal and sides with the Fourth District instead, counties statewide will recover meaningful discretion to say no. Until then, the answer in Illinois depends on the district a project is in, and Grundy County is squarely in the one where compliant applications must be approved.