Developers don't find land by accident. Before a solar company calls a landowner, the parcel has already been run through a filter — substation distance, flood exposure, wetlands, protected land designations, acreage. The offer arrives because the land passed. The silence, usually, means it didn't.
Running the same checks yourself before making an offer — or before investing time pursuing a parcel — takes a few hours and a handful of free public databases. Most of the filters a developer uses are government datasets anyone can access.
What the Filter Actually Checks
Solar land selection is not primarily about price or aesthetics. Developers screen for constraint-free parcels that can connect to the grid without triggering expensive permitting battles or prohibitive upgrade costs. A parcel with a low price and a good location fails immediately if it carries a flood designation, a wetland, or a conservation easement.
The filters fall into two categories: hard stops and soft factors. A hard stop disqualifies a parcel regardless of everything else. A soft factor affects project cost or complexity but does not automatically kill a deal.
| Filter | Where to look | Type |
|---|---|---|
| FEMA flood zone | FEMA Flood Map Service Center (msc.fema.gov) | Hard stop if Zone AE, VE, or any SFHA designation |
| Wetlands | USFWS National Wetlands Inventory (fws.gov/program/national-wetlands-inventory) | Hard stop if emergent, forested, or scrub-shrub wetlands cover a significant portion |
| Protected areas | PAD-US Data Explorer (protectedlands.net) | Hard stop if parcel overlaps a national park, wildlife refuge, or conservation easement |
| Substation proximity | Satellite imagery; Sunnyplans | Warning sign above 10 miles; typically unviable above 15 miles |
| Parcel acreage | County assessor records | Hard stop below ~30 acres for utility-scale solar; ~5 acres for BESS |
| Zoning classification | County planning department | Agricultural A-1 usually compatible; rural residential often requires a Special Use Permit |
| Slope and terrain | USDA Web Soil Survey; topographic maps | Above 5% grade increases construction cost significantly; above 10% typically unviable |
| Title encumbrances | Preliminary title report | Hard stop if conservation or pipeline easement crosses the main site area |
| Solar irradiance | NREL PVWatts Calculator (pvwatts.nrel.gov) | Below 4.5 kWh/m²/day is marginal for utility-scale projects |
The Two Filters That Kill Most Deals
Flood zones and wetlands disqualify more parcels than any other factors, and they're the quickest to check.
Flood zones: FEMA publishes flood maps at parcel-level resolution through the Flood Map Service Center. In many parts of the Southeast and Gulf Coast, FEMA flood zone AE boundaries cover a significant share of otherwise viable agricultural land — and any parcel inside the SFHA is a hard stop for most developers. Insurance costs and permitting requirements in a Special Flood Hazard Area make projects economically marginal. Zone X parcels carry no significant flood risk and pass this filter cleanly. Five minutes on the FEMA map can rule out a parcel before any other research is done.
Wetlands: The US Fish & Wildlife Service maintains the National Wetlands Inventory — a public dataset mapping wetland types at parcel resolution. Emergent wetlands, forested wetlands, and scrub-shrub wetlands on or adjacent to a parcel trigger Clean Water Act review under Section 404. A formal wetlands delineation is typically required before permitting proceeds, and if significant wetlands are confirmed, the project may be denied outright or redesigned at prohibitive cost. The NWI map is free and takes a few minutes to run.
Substation Proximity: The Grid Check
Once flood and wetland checks pass, substation proximity is the next variable that most directly affects whether a developer will lease the land. A parcel 1.5 miles from a substation with available capacity faces a fundamentally different cost equation than one 12 miles away. The farther from existing grid infrastructure, the longer and more expensive the interconnection path — and the higher the risk that interconnection studies come back with costs the project cannot absorb.
Satellite imagery shows transmission lines and substations. County utility maps are more detailed. The presence of visible transmission infrastructure near a parcel is not a guarantee of viable interconnection, but its absence is a reliable warning.
Zoning and Title: The Checks Most Buyers Skip
Zoning: Solar projects are not permitted by right in most zoning classes. Agricultural A-1 zoning allows solar as an accessory use in most US states, but many counties require a Special Use Permit even on agricultural land for any installation above 1 MW. Rural residential zoning is more restrictive. County planning websites publish current codes and often show which zones require SUPs for solar. A 15-minute call to the planning department prevents purchasing land that will require a contested variance application.
Title encumbrances: A preliminary title report reveals easements, liens, and prior recorded agreements. A conservation easement or pipeline easement running through the center of a site is a hard stop — either the buildable footprint shrinks to the point of unviability, or the project economics collapse. Title companies issue preliminary reports for a few hundred dollars. It is the last check before making an offer on a parcel that has passed every other filter.
Sunnyplans screens parcels against PAD-US protected area data and the National Wetlands Inventory, and shows substation proximity for every indexed listing — the three filters that most commonly determine whether a developer pursues a site.