Screening land for ground-mount solar is a different problem from screening a roof, and the habits carry over badly.
On a roof, the building is the constraint. The footprint is fixed, the ownership is usually one entity, and the electrical service already exists. On raw land almost nothing is fixed. The usable area has to be derived, the constraints are layered on top of each other, and the two questions that decide the project — grid capacity and entitlement — are not in any public dataset.
A desktop screen is still worth running. It just has to be honest about which questions it can close and which it can only queue.
Net buildable acreage is the only acreage that counts
Gross parcel acreage from the assessor is the starting figure and it is almost always wrong for this purpose. Start subtracting.
- Zoning setbacks from every property line, and any larger setback the jurisdiction applies specifically to solar or to adjacent residential use.
- Recorded easements: transmission rights of way, pipelines, access easements, drainage. Some appear in county GIS layers; some only appear in the title work.
- Mapped wetlands and their buffers, plus streams and any riparian buffer the state applies.
- Slope steep enough that racking cost or grading cost rules it out under your own thresholds.
- Existing structures, ponds, tree stands you intend to keep, and any area held back for stormwater.
What remains is net buildable acreage, and it is the figure to rank on. Contiguity matters as much as the total. Forty acres in one block supports a different layout from forty acres split into three pieces by a stream and a right of way.
Record the subtraction, not just the result. When a landowner or a developer challenges the number, you need to show which constraint removed which acres.
Slope and aspect from public elevation data
Public elevation data will get you a defensible first pass on terrain. USGS 3DEP publishes lidar-derived bare-earth elevation where a county has been flown and coarser models where it has not, and either supports a slope and aspect surface across the parcel.
Three things to check on that surface. How much of the net area falls under your slope threshold. Which way the workable ground faces. And whether the slope is one consistent plane or a broken surface of small rises, because a broken surface costs more in racking and grading than an average slope figure suggests.
Set your slope thresholds from your own racking and civil experience and apply them uniformly. A screen is only comparable across parcels if the same numbers are used everywhere.
Bare-earth elevation does not describe soil. Bearing capacity, rock depth, corrosivity and groundwater all decide foundation cost, and all of them need a geotechnical investigation.
Land cover tells you what clearing will cost
Current aerial imagery and public land-cover data separate the parcels that are ready from the parcels that need work. Open pasture or fallow cropland is the cheap case. Mature forest means clearing, stump removal, disposal, and often an erosion-control plan and a longer permitting path.
Imagery age matters here more than people expect. Public aerial programmes fly on a multi-year cycle, so a parcel that reads as open may have grown in, and a parcel that reads as wooded may have been cleared. Note the capture date next to the finding.
Prior land use is worth a look while you are in the imagery. Old industrial activity, quarrying, landfill or fuel storage can turn into an environmental review that outlasts the whole rest of the schedule.
Distance to a line is not capacity on that line
This is the single most common overstatement in ground-mount screening. A parcel sitting under a transmission line looks like an interconnection story. It is not one until somebody studies the circuit.
Distance to a plausible point of interconnection is a legitimate screening variable, because distance drives the cost of the line extension. It is not a capacity finding. Hosting capacity depends on the circuit's existing load and generation, the substation, protection settings, and the queue of projects already ahead of you.
- Measure distance to the nearest plausible point of interconnection, not straight-line distance to the nearest visible conductor.
- Note the route the line extension would have to take, and whose land it crosses.
- Identify the serving utility from public service-territory data, so the parcel is at least matched to the right rules.
- Check the utility's published hosting-capacity map if it has one, and treat it as indicative rather than final.
- Record the queue position question as an open check, because the queue is where most ground-mount projects actually die.
Zoning, entitlement, environment and access
The remaining screening layers are cheaper to check and easy to skip. Skipping them is what produces a shortlist full of parcels that cannot be built.
- Zoning district and whether solar is permitted by right, permitted with a special use permit, or not addressed at all. Silence in the ordinance is a risk, not a green light.
- Overlays that sit on top of the base district: agricultural preservation, scenic corridors, airport approach surfaces, historic districts.
- Whether the parcel is enrolled in an agricultural or forestry tax programme, which can carry a rollback penalty on conversion.
- Mapped flood zones across the buildable area, remembering that a flood zone is a regulatory designation rather than a measurement of risk.
- Habitat and species screening layers, which set the schedule as much as the outcome.
- Frontage on a public road, and whether it can carry construction traffic and a delivery turn. Access over a neighbour's land is an easement negotiation, not an access plan.
- Ownership of record, the number of parcels involved, and whether an assemblage would need several owners to agree at once.
On ownership, treat the assessor record as a lead rather than a fact. Counties commonly lag a transfer by a full assessment cycle, entity names hide the actual decision maker, and a parcel held in a family trust or an estate may have several people who must agree before anything happens.
What the screen should hand back
The useful output is not a suitability score on its own. It is a ranked list where each parcel carries its net buildable acreage with the subtraction shown, its slope profile, its land cover and imagery date, its distance to a plausible interconnection point, its zoning path, and its access situation.
Next to that, each parcel carries its open checks: the title work, the geotechnical investigation, the interconnection application, the pre-application conversation with the planner, and the landowner conversation.
That is what a desktop screen is for. It decides the order in which you spend money on site visits and studies. It does not decide the project.