The difference between a parcel that can host a solar farm and one that can't isn't always about zoning. Sometimes a parcel is in exactly the right zone, the right distance from a substation, the right acreage — and still can't move forward because the county's planning board said no.
That decision happens through a Special Use Permit. Understanding what it is, when solar projects trigger one, and what the approval process actually looks like matters a lot when you're evaluating whether a piece of land has a realistic development path.
What makes solar a "conditional" use
Zoning ordinances in most US counties divide activities into three buckets: things that are allowed without any review (a house in a residential zone, a crop on agricultural land), things that are allowed only after formal approval, and things that are outright prohibited.
Large-scale solar generation — utility-scale projects above roughly 1 MW, which is the threshold many county ordinances use — almost never falls into the first bucket. In most counties, it's a conditional use or a special use. That means it's legally permissible, but only after a county board evaluates the specific project and says yes. The permit granted through that process is the Special Use Permit, or SUP.
The difference between "permitted by right" and "conditional use" matters in a concrete way: a use that's permitted by right can proceed without a public hearing. A conditional use requires one. That hearing introduces timeline risk, political risk, and the possibility of conditions that change what a project is worth to a developer.
What the process actually involves
An SUP application almost always comes from the developer, not the landowner. The developer prepares a package: a site plan showing panel layout, access roads, setbacks, and screening; an environmental assessment; stormwater management documentation; a decommissioning plan. This package gets submitted to the county planning department.
The planning department reviews the application for completeness and checks it against the county's solar ordinance or its general conditional use standards. Property owners within a notification radius — typically 300 to 1,000 feet depending on the county — receive written notice. The county then schedules a public hearing.
At the hearing, the developer presents the project. Neighbors can speak. The county commission or planning board then votes: approve, approve with conditions, table pending more information, or deny.
In counties with established solar ordinances — DeKalb County in Illinois processed multiple solar SUPs in 2025 — the process runs roughly 3 to 9 months from application to decision. In counties where solar is new, timelines stretch. Staff who haven't reviewed a solar SUP before take longer to process the application, and contentious hearings often get continued to future dates.
What conditions come with approval
Approvals nearly always carry conditions. Some conditions are standard enough to expect. Others vary enough by county to affect whether a project remains economically viable.
Setbacks are universal, but the distances are not. A 50-foot setback from non-participating property lines is common as a baseline. Some ordinances require 150 feet from any occupied structure, with a planted buffer included in that distance. A handful of counties in stricter jurisdictions have pushed setback requirements to 300 or 500 feet from residences — distances that, on a smaller parcel, can eliminate enough buildable acreage to break the economics.
| Condition | Typical range | What it means in practice |
|---|---|---|
| Setback from property line | 10–150 ft | Wider setbacks reduce usable acreage on smaller parcels |
| Setback from occupied structures | 50–500 ft | The main variable — some counties scale this by project size |
| Perimeter screening | Vegetative buffer required | Usually 6–10 ft of mixed evergreen and deciduous planting, installed before panels go in |
| Decommissioning bond | Surety bond or escrow | Amount formula varies by county; covers estimated removal cost at end of project life |
| Noise limit | 65 dBA at property line | Standard in most ordinances; not usually a binding constraint for solar |
| Panel height | 15–20 ft maximum | Rarely a problem in practice |
The decommissioning requirement is worth understanding in detail. Most counties now require a financial guarantee — a surety bond, letter of credit, or escrow account — that covers the estimated cost of removing panels and restoring the land when the project ends, typically 20 to 35 years out. The formula for calculating the required amount varies by county. On a large project, this can reach several hundred thousand dollars in a developer's financial model, and a county that requires an unusually high bond can make an otherwise viable site harder to finance.
When applications fail
The Madison County Board in Illinois voted on several solar SUP applications in November 2025 — denying permits for projects in Fosterburg and Moro while approving one in New Douglas. The project that passed had something the others didn't: the developer had worked directly with neighboring landowners before the hearing and reached agreement on setbacks, tree planting, and a bond payment structure. The community opposition that showed up to sink the other projects never materialized, because the concerns had been addressed before anyone testified.
That pattern is consistent across jurisdictions. Projects fail at the SUP stage most often when the developer treats the public hearing as a formality rather than as the decision point it is. Neighbors who arrive with specific objections — glare onto adjacent properties, drainage changes, traffic from construction — can change the outcome of a hearing when the developer doesn't have prepared responses. Neighbors who've already been consulted and had their concerns incorporated into the site plan have less reason to oppose the project publicly.
The other common failure mode is a mismatch between the project and the county's long-range plan. Most counties maintain a comprehensive plan — a land use document that guides zoning decisions. A parcel designated in that plan as "agricultural preservation area" or "rural residential character" is carrying a signal: the board is likely to be skeptical regardless of technical compliance. The legal standard for approving a conditional use in most jurisdictions includes consistency with the comprehensive plan, and county boards apply that standard. Checking the comprehensive plan for the relevant parcel before pursuing a site is worth doing.
The moratorium problem
The harder version of the SUP question isn't whether a project will get approved — it's whether the county is even accepting applications.
A 2025 report from Columbia Law School's Sabin Center for Climate Change Law found that by end of 2024, at least 459 counties and municipalities across 44 states had adopted severe local restrictions on siting renewables — a 16% increase from the year before. In Greene County, North Carolina, the county's Board of Adjustments approved a NextEra Energy SUP for a 1,100-acre project in February 2025, then county commissioners placed a two-year moratorium on new solar SUP applications the following month. Dearborn County, Indiana approved a 12-month moratorium in February 2026 after residents raised concerns about a proposed 1,200-acre solar farm in Manchester Township. Over a dozen Colorado counties have enacted temporary moratoriums while revising their zoning codes, with several still in effect as of early 2026.
A moratorium creates a specific problem for buyers: a parcel can sit in a county where solar is theoretically allowed under the zoning ordinance — conditional use, no prohibition — but where the county has temporarily stopped accepting SUP applications. That's not a permanent ban, but it adds real time to any development path, and some counties have extended moratoriums rather than lifted them.
The states where this has been most active include Illinois, Indiana, Ohio, and North Carolina. Illinois responded to the conflict between local restriction and statewide energy goals by establishing state-level siting standards in 2023 that county ordinances cannot undercut. Whiteside County settled a lawsuit in 2025 after being accused of applying SUP standards that violated state law. Ohio and Indiana have not similarly preempted county authority, leaving more variation — and more uncertainty — at the local level.
What to look up before making an offer
Understanding what makes land viable for a solar farm covers the physical filters — acreage, slope, flood zone, substation proximity. The SUP question sits on top of all that as the regulatory layer, and it's county-specific in a way that physical constraints aren't.
Two things are worth checking before committing to a parcel. First, the county zoning ordinance. Find the specific zone designation for the parcel — typically A-1, A-2, or equivalent agricultural zoning in rural areas — then look for how large-scale solar is classified: permitted use, conditional use requiring an SUP, or not addressed. If solar isn't mentioned, call the county planning department directly. An unaddressed use is often treated as prohibited in practice, but the department will give you the official interpretation.
Second, whether the county has an active moratorium or a pending ordinance revision. This won't appear in the zoning code itself — it's in recent county commission meeting minutes, which most counties publish online. Searching the county name plus "solar moratorium" or "solar ordinance" filtered to the past 12 months will usually surface anything relevant. A county in the middle of revising its solar rules has a genuinely uncertain timeline for any new SUP application, and the county's current posture on solar — whether it's still accepting applications, what conditions it's been attaching — determines whether the SUP process is worth entering at all.
Sunnyplans maps substation proximity, protected area overlaps, and wetland constraints for individual parcels across US states — the inputs developers check before deciding whether a site is worth entering the SUP process.