NEC 110.31 & 690.31(G) Ground-Mount Solar Perimeter Fencing, Wire Mesh Skirts & Livestock Protection
Because the back side of a ground-mount solar array is only 2 to 5 feet off the ground, any child, pet, deer, goat, or passerby can walk right behind the panels and grab the 500V DC MC4 pigtails and junction boxes. Under NEC 690.31(A), exposed single-conductor PV wires behind a low ground-mount array are considered "readily accessible"—meaning your inspector will fail the array unless you either enclose the array inside a locked perimeter fence OR screen the back/underside of the rack with wire mesh!
Engineering Trade-Off & Code Comparison Matrix
| Engineering Parameter | Conventional / Unoptimized Approach | Engineered Ground-Mount Specification | Field Verdict & ROI Impact |
|---|---|---|---|
| NEC 690.31(A) "Readily Accessible" Wire Rule | Open ground mount in an unfenced yard with exposed MC4 wires hanging behind the panels | Option A: 6-ft locked perimeter fence around the property/array | Option B: 1/2" PVC-coated hardware cloth / expanded metal screen bolted across the rear of the rack | If your property isn’t fully fenced, adding a rear galvanized wire mesh screen on the rack is 80% cheaper than building a 6-ft chain-link fence around the array |
| Goat, Sheep, Cattle & Deer Protection | Livestock rubbing against aluminum module frames and chewing dangling PV pigtails | 48-inch woven-wire agricultural fence (4-ft setback from drip edge) OR elevated 8-ft agrivoltaic cattle frame | Goats and horses will climb on or chew exposed low-profile ground mounts—always fence out goats, horses, and cattle! |
| Weed Growth & Lawnmower Rock-Chip Defense | Mowing tall weeds right next to the bottom glass edge (high velocity rock chips shatter tempered glass!) | 4-foot crushed gravel skirt around array perimeter + minimum 30" leading-edge panel height | #1 cause of shattered residential ground-mount panels is a zero-turn lawnmower throwing a pebble at the bottom glass |
| Wildlife Passage (Agricultural / Conservation Zoning) | Chain-link fence buried tight to grade blocking small wildlife | Fixed-knot agricultural deer fence with 6-inch bottom wildlife gap (where permitted by AHJ) | Satisfies rural conservation commission conditions while keeping deer and trespassers off the array |
Foundation Embedment, Pullout Capacity & Design Schedule
| Soil / Climate Condition | Embedment / Config | Uplift / Capacity | Lateral / Secondary Spec | Recommended Engineering Spec |
|---|---|---|---|---|
| Unfenced Suburban / Rural Acreage Lot | Back-of-Array Wire Guard Screen (NEC 690.31(A) Compliance) | Renders PV leads "Not Readily Accessible" (Requires tools to open) | $280–$450 Material Cost | 14-Gauge 1/2" x 1/2" Black PVC-Coated Welded Wire Mesh bolted to rear racking struts with stainless Tek screws |
| Full Perimeter Security Fence (AHJ Zoning Mandate) | 6-Foot Chain-Link or Agricultural Woven-Wire Fence + Padlocked Gate | 10-Foot Setback from Array Drip Edge (For Mower/Snow Clearance) | NEC 250.118 / 250.4 Metal Fence Bonding if within 5 ft of array | 6-ft Galvanized/Black Vinyl Chain-Link or 6-ft Fixed-Knot Cedar/T-Post Farm Fence w/ "DANGER: HIGH VOLTAGE SOLAR" sign |
| Active Sheep Grazing Pasture | 30" Minimum Panel Edge Height + Enclosed Conduit & Wire Mesh | Sheep graze safely underneath panels (unlike goats, sheep do not climb) | Protect all MC4 leads in metal channel / wire guard | Enclose all module-to-module MC4 jumpers inside covered rail channels and Sch 80 PVC risers |
| Cattle / Horse Pasture | Dedicated 5-Strand Barbed/High-Tensile Electric Exclusion Fence | Resists 1,500-lb bovine rubbing forces | Minimum 6-ft clearance from panel edges | 6" Treated Wood Corner Braces + 5-Strand High-Tensile Wire w/ Hot Top Strand (unless using 9-ft elevated cattle rack) |
3-Step Field Execution & AHJ Inspection Protocol
Confirm AHJ Interpretation of NEC 690.31(A) Accessibility
Ask the local electrical inspector during permitting whether a locked perimeter property fence, a 6-ft array fence, or a tool-removable rear wire-mesh screen is preferred to guard exposed under-array PV conductors.
Install 4-Foot Gravel Mowing Buffer Around Array
Extend geotextile fabric and crushed gravel 4 feet past the front and sides of the solar panels so lawnmowers and string trimmers never operate close enough to sling rocks into the tempered glass.
Bond Metal Fencing Located Within 5 Feet of Array Structure
If installing a metal chain-link fence within 5 feet of the solar racking or inverter, connect a #6 AWG copper bonding jumper between the fence posts and the array grounding system to prevent touch-potential hazards.
AHJ Building & Electrical Permit Plan-Check Note
Copy and paste this code-compliant specification note directly onto your ground-mount site plan or single-line diagram.
NEC 690.31(A) CONDUCTOR ACCESSIBILITY & PERIMETER PROTECTION NOTE: 1. Guarding of Exposed PV Conductors: Pursuant to NEC 690.31(A), PV system DC circuits installed below 8 feet on an open ground-mount structure are guarded against ready accessibility by [LOCKED_6_FT_PERIMETER_FENCE_OR_BOLTED_14_GAUGE_WIRE_MESH_REAR_ENCLOSURE_SCREEN] requiring a tool for removal. 2. Warning Signage: Permanent UV-stabilized warning signs reading "WARNING: PHOTOVOLTAIC POWER SOURCE" are affixed to all access sides.
Need to Size the Underground Trench Wires for This Ground Mount?
Calculate exact AWG/kcmil wire gauge, voltage drop, NEC 250.122(B) EGC upsizing, and PVC conduit size.
Frequently Asked Ground-Mount Engineering Questions
Can my electrical inspector really force me to build a fence around my ground-mount solar panels on my own 10-acre rural property?
Under NEC 690.31(A), single-conductor PV wires behind a solar panel are only allowed to be exposed where they are "not readily accessible" (which the NEC defines as either above 8 feet off the ground or behind a locked fence/screen requiring a tool to open). You do NOT have to build an expensive 6-foot fence if you simply bolt a neat 1/2-inch black PVC-coated wire mesh screen across the back of the racking frame to cover the wires!
Why did one of my ground-mount solar panels shatter into a spiderweb pattern in the middle of summer?
Over 90% of warm-weather glass breakage on residential ground mounts is caused by a riding lawnmower or string trimmer throwing a small pebble at 150 mph into the bottom edge of the tempered glass. Putting down a 4-foot wide strip of weed barrier and decorative gravel in front of the array eliminates mowing near the glass.