By Jennifer Kirstens · 2026-08-31 · 13 min read

Ground-mount arrays split cleanly into three markets: residential (2–20 kW, single-row or two-row pole/screw), light commercial (20–100 kW, driven pipe post), and utility (100+ kW, ground screw or driven pile with tracker option). This reference covers the first two — the range that comes through PES on a daily basis. For utility-scale project pricing, contact the PES commercial desk through the Axis portal.

Ground-mount arrays have full exposure and typically higher tilt angles (25–35°) than roof-mount arrays. Both wind and snow load a ground array harder than a roof-mount system for the same nameplate.

Ground-mount solar is not a rooftop install with dirt underneath — the site prep, drainage, and long-term erosion planning are as important as the racking spec. Site prep sequence for a typical 20–50 kW residential/commercial ground mount:

1. Survey and soil bore. Get a survey to establish exact array footprint, and 1–2 soil bores to determine soil type, depth to bedrock, and water table. This drives foundation selection.
2. Vegetation clear and grade. Strip topsoil and grade the array footprint to a maximum 5% slope. Retain topsoil for post-install stabilization.
3. Access path. Establish a truck access path for the pile driver or auger to reach every post location. On sensitive soil, use temporary aluminum matting to prevent rutting.
4. Utility locate. Call 811 for underground utility locate before any drilling or driving. Ground-mount posts have injured buried lines many times — always locate first.
5. Post layout survey. Stake every post location per the OEM engineering drawing. Verify with tape and transit before driving.
6. Post driving or drilling. Drive pipe posts with a hydraulic post driver, or auger for concrete piers, or install helical/driven ground screws with a screw driver rig.
7. Verify plumb and elevation. Each post should be plumb within 0.5° and its top elevation within 0.25" of the design elevation. Wide variance means rails cannot be installed without stress on the beam splice.
8. Backfill and compact. Where soil was disturbed, compact backfill to 95% Proctor density.
9. Install rails and modules. Standard rail install per OEM instructions.
10. Vegetative cover. Reseed disturbed soil under the array with a low-mow drought-tolerant seed blend. Prevents erosion and cuts long-term vegetation-management cost.

Foundation selection determines site-install time, cost, and long-term durability. Here are the extended trade-offs beyond the summary table earlier in this guide.

Helical ground screw is the modern standard for utility-scale and commercial fixed-tilt. A hydraulic screw driver installs a 5–8 ft corkscrew-shaped pile in 5–15 minutes. Pull-out capacity is soil-tested and typically ranges 3,000–8,000 lb per pile. Advantages: no cure time, no excavation, minimum soil disturbance, immediate load capacity. Disadvantages: requires screw-driver rig on site (rental or subcontractor), poor in dense rock or shallow bedrock.

Driven pipe post is the workhorse for utility scale and much commercial. A hydraulic pile driver drives a Sch-40 or Sch-80 steel pipe post 5–7 ft into the soil. Pull-out is by soil friction and end bearing. Cheapest foundation per unit, fastest install (5–10 min per post). Disadvantages: pipe post has some corrosion vulnerability at the ground line; verify with hot-dip galvanized or FBE coating.

Concrete pier is the traditional foundation for high-pull requirements or rocky soil. Drill a 12–24" diameter hole to 4–6 ft depth, drop in rebar, pour concrete. 3-day cure required before loading. Advantages: highest pull-out capacity, works in any soil including partial rock. Disadvantages: longest install time, cure delay, largest disturbance footprint.

Ballasted concrete block is for asphalt-parking-lot canopy or grade-level installs where soil disturbance is prohibited. Precast concrete blocks (500–2,000 lb each) provide anchoring via weight and footprint. Very high per-block cost; use only when other options aren't feasible.

Ground-mount arrays have to space rows to prevent inter-row shading. The Ground Coverage Ratio (GCR) — module area divided by total array footprint — typically lands between 0.35 (open spacing, minimal shading) and 0.55 (tight spacing, some inter-row shading acceptable for the economics).

Rule-of-thumb row spacing at a latitude L and tilt T:

Row-to-row spacing (ft) = Module height (ft) × sin(T) / tan(60° − L)

For a 6.5-ft-tall module row at 30° tilt at latitude 40° (Denver), the row spacing works out to about 6.5 × 0.5 / tan(20°) = 8.9 ft between rows. That means for every 6.5 ft of module you consume 8.9 ft of ground — a GCR of 0.42.

The tradeoff: tighter GCR (0.5+) fits more kW on a given parcel but sacrifices 3–5% of annual energy to winter-morning shading. For grid-tied 30-year economics on cheap land, GCR 0.35–0.42 is typically optimal. On expensive urban or peri-urban parcels, GCR 0.5+ can pencil out.

Unlike rooftop solar, ground-mount arrays have relatively few fire-code constraints. The main regulatory paths for ground mount:

• Local zoning — most municipalities require ground-mount arrays to be set back from property lines by 5–15 ft. Some restrict height (typically max 12–15 ft tall) or require screening from public view.
• NEC 690.31 — DC wiring must be in raceway from module junction box back to the DC combiner if it is exposed to physical damage risk.
• NEC 690.11 — arc-fault protection required on DC circuits operating at 80 V or above. Applies to string inverters; not required with microinverters.
• Structural PE — required for ground-mount over ~10 kW in most jurisdictions, and for any array on a slope or in a wind-loading environment above baseline.

Ground-mount cost per watt is typically 30–50% higher than roof-mount for the same nameplate, because of the foundation, structural steel, and site prep. But it's often the only option — no roof access, poor roof condition, or an owner who wants to preserve roof warranty. Here's what a typical ground mount actually costs at three scales:

5-kW residential pole/screw ground mount:

• Racking (Unirac ULA or IronRidge Ground Mount Kit): $900–$1,200
• Ground screws (8 screws @ $50 each): $400
• Screw driver rental / labor (1 day): $500–$800
• Site prep, trenching for conduit run, backfill: $500–$1,000
• Steel post + rail install labor (2 days for a 2-person crew): $1,200–$1,600
• Total ground-mount structure cost: $3,500–$5,000
• Adds $0.70–$1.00/W to the total system cost vs an equivalent roof-mount

20-kW small commercial pipe-post ground mount:

• Racking (IronRidge Ground Mount Kit + XR1000): $3,000–$4,000
• Pipe posts (galvanized Sch-40): $1,500–$2,000
• Post driver subcontract (2 days): $1,500–$2,500
• Site prep + soil testing: $2,000–$3,500
• Install labor (5–7 days for a 3-person crew): $5,000–$7,500
• Total ground-mount structure cost: $13,000–$19,500
• Adds $0.65–$1.00/W vs roof-mount

100-kW commercial ground screw ground mount:

• Racking (IronRidge Ground Mount Kit or K2 CrossRail 80): $18,000–$22,000
• Ground screws (120 screws): $6,000–$10,000
• Screw installation subcontract (5 days): $8,000–$12,000
• Site prep, trenching, grounding, gravel base: $10,000–$18,000
• Install labor (15–20 days for a 4-person crew): $15,000–$25,000
• Total ground-mount structure cost: $57,000–$87,000
• Adds $0.57–$0.87/W vs commercial roof-mount

Ground-mount solar's cost premium over roof-mount is offset by two economic drivers unique to ground: land use flexibility and community-solar economics.

Land use. Ground mount can go on parcels that have no other productive use — non-arable soils, brownfields, retired quarries, agricultural buffer strips. In many states, dual-use agrivoltaics (crop or grazing under elevated ground-mount) is now permitted, capturing dual revenue from land that previously earned only crop yield.

Zoning. Most municipalities have added specific ground-mount zoning provisions in the last 5 years. Typical residential-district provisions limit ground-mount to accessory-use scale (typically 10 kW), require 5–15 ft setback from property lines, and cap height at 12–15 ft. Agricultural and industrial zones allow much larger ground-mount installations — check the specific parcel's zoning before pursuing.

Community solar. In states with community solar programs (NY, MA, MN, IL, CO, MD, DC, FL, and growing), ground-mount solar farms in the 1–5 MW range can sell power to residential subscribers who don't have suitable roofs. Community solar economics support the higher $/W of ground mount because the land + array unit can be built at low incremental cost. PES quotes racking for community-solar-scale projects on a project basis; contact commercial@pes.supply.

Single-axis trackers (SAT) rotate the array east-to-west through the day, increasing annual energy yield by 15–25% vs fixed-tilt. They require more sophisticated ground-mount hardware (torque tube, driven pile, drive motor at each row) and more O&M attention.

Trackers become economical above roughly 1 MW where the 15–25% yield boost outweighs the 20–30% capex premium. Below that scale — the 2–100 kW range this guide covers — fixed-tilt is almost always the right choice.

Neither IronRidge, Unirac, K2, nor any other brand PES stocks currently makes a single-axis tracker for the 2–100 kW residential/light-commercial market. Trackers in this size range are a specialty product from Nextracker, Array Technologies, or GameChange Solar — outside the current PES catalog.

If your job needs a tracker, we can source it project-specifically through our commercial desk, but the racking spec, foundation design, and controls are significantly different from a fixed-tilt install.

Ground-mount arrays have a physical advantage over roof-mount for NEC 690.47 grounding compliance — the racking is already connected to earth via the foundation. But the grounding-electrode requirements still apply, and a well-designed ground-mount includes an explicit earthing system.

Standard ground-mount grounding scheme:

• One 8 ft copper-clad ground rod driven at each corner of the array field
• #6 AWG solid copper bonding conductor bare-buried 18" deep, tying all ground rods together in a ring
• One additional bonding conductor from the ring back to the DC combiner or AC main service ground
• Bond every ground-mount post to the ring at its base
• The array racking is UL 2703 listed, so the module frames and rails self-bond, but each row still needs a listed EGC from the row's rack lug to the grounding ring

Ground-rod resistance should be checked with a clamp-on tester or three-point fall-of-potential test after install. Target: less than 25 ohms per NEC 250.53(A)(2). If measurement exceeds 25 ohms, additional rods driven at 8 ft spacing usually solve the problem.

Vegetation under and around a ground-mount array can shade modules, obstruct airflow, and create a fire hazard. Ongoing vegetation management is a 25-year O&M cost. Common approaches:

• Low-mow seed blend. Native or drought-tolerant grasses that grow to ~6 inches and stay there. Minimum-maintenance option; annual mowing or none at all in dry climates.
• Sheep grazing (agrivoltaics). Contract with a local shepherd to graze sheep under the array. Sheep don't damage modules and don't reach high enough to cast shading. Popular for utility-scale but works for 100 kW+ commercial ground.
• Pollinator planting. Wildflower blend that supports pollinators and typically requires only annual mowing. Popular with sustainability-focused corporate solar buyers.
• Gravel base. Weed-suppressing landscape fabric under a 3–4" gravel layer. Highest upfront cost, lowest annual maintenance. Popular for small residential and off-grid installs where labor is scarce.
• Herbicide + bare soil. Effective but environmentally problematic and increasingly prohibited by local ordinance. Avoid.