Before anyone orders a helix ground screw, one check decides the size: what the soil at that exact spot will hold.
A helical ground screw is a galvanized steel shaft with a helical blade near the tip that is screwed into the soil to anchor a solar pole or mount without concrete. It can take the mount the same day and can be backed out and reused. The soil sets the capacity, so the right size comes from a soil check or the supplier's load table for that soil.
The sections below explain what a helical ground screw is and how it holds a mount, then compare it with a concrete footing and a driven pile in one table. They cover typical sizes, galvanized coatings and why some screws are green, a six-step install, and what drives the price of a quote.
LinkSolar supplies the above-ground half of the job: pole mount kits for a single panel on a screw or post, tilt mounts and brackets. Send the soil description and the pole or leg pattern, and LinkSolar helps spec the foundation underneath so the screw head and the mount match.
What is a helical ground screw, and how does it hold a solar mount?
A helical ground screw is a steel shaft with a helical blade near the tip and a head or flange on top, and it holds a solar mount by bearing on the soil around and above the blade. It goes into the ground by rotation, not by hammering. Once it is set, the pole or frame bolts directly onto the head.
A typical ground screw has three parts, and each one does a separate job.
- Shaft: The shaft is a steel tube that carries the load from the mount down to the helix and resists sideways push along its length.
- Helix: The helix is the blade near the tip that pulls the screw down as it turns and resists pull-out once it is in place.
- Head: The head is a flange head, U-bracket or threaded adaptor on top that the pole or tilt leg bolts to.
Installation torque is the reading that links the screw to the soil it sits in. According to Geoengineer.org's page on helical piles, the torque needed to turn a helical pile in is used as a verification of its strength. Harder turning generally means firmer soil, so installers watch the torque as the screw goes down.
The same source notes that a helical pile can be removed when the use is temporary. Its installation is minimally invasive compared with a driven pile, where the soil is heavily vibrated. For a solar mount, that means the foundation can come back out if the array moves to a new spot.
Ground screws suit small solar sites where pouring concrete is awkward or the ground is leased. A single pole for a camera or sensor sits on one screw, and a tilt-leg frame for a cabin array sits on a set of screws under its feet, as in these off-grid cabin power layouts. LinkSolar supplies the above-ground half of that foundation, the pole mounts, tilt legs and brackets that bolt onto the screw head.
Specs to compare before you order: ground screw, concrete footing or driven pile
For a small ground-mount solar array, a helical ground screw is the faster and removable foundation, a concrete footing suits a permanent mount on ground you can dig, and a driven pile suits large arrays with machine access. The spec that separates them on a small site is curing. A ground screw can take the mount the same day, while a concrete footing has to cure before it carries any load.
The table compares the three foundations on install time, tools, soil, frost and removal, and typical use for a small solar mount.
| Foundation | Install time (typical) | Tools | Soil suitability | Frost and removal | Typical use |
|---|---|---|---|---|---|
| Helical ground screw | Same day, takes the mount straight away | Hand-held or machine-mounted rotary driver | Most soils; rocky ground may need a pilot hole; expansive clay can stop it early | Helix sits below local frost depth; backs out and can be reused | Single poles, tilt-leg frames, rows of panels on leased ground |
| Concrete footing | Dig, pour, then cure before loading | Auger or spade, mixer, formwork | Almost any soil you can dig | Footing sits below local frost depth; stays in the ground | Permanent pole mounts, garden sites without machine access |
| Driven pile | Fast per post once the machine is on site | Machine-mounted pile driver | Uniform soils with few stones; the soil is heavily vibrated during driving | Depth set per project; removal needs extraction | Multi-row arrays of full-size modules |
If the ground screw row matches your site, compare pole mounts that sit on a screw foundation and match the pole to the screw head. LinkSolar supplies the above-ground half, pole mount kits, tilt legs and brackets, to fit the head your screw supplier specifies.
Install time and suitability are typical. Capacity depends on the soil and comes from a soil check or the supplier's load table.
According to the Geoengineer.org helical piles page, a helical pile goes in with little disturbance compared with a driven pile, and it can be removed when the use is temporary. The same page notes that expansive soils can cause early refusal. For a small array on leased or rented ground, removability is often the spec that settles the choice.
A concrete footing is the long-standing choice where the mount is permanent and a driver cannot reach the spot. Dug soil with stones that would stop a screw is still workable for a footing. The cost in time is the digging, the formwork and the wait for the concrete to cure before the pole goes on.
Ballast is a fourth option where nothing may go into the ground, such as a concrete pad or a flat roof, and this guide on ballast instead of anchors on a flat surface covers the method. Driven piles make sense once an array grows to several rows of full-size modules, and the racking guide explains load paths for multi-row racking on piles.
What size ground screw does a pole mount or tilt-leg array need?
The size of a solar ground screw follows from the soil at the site and the load the mount puts on it, so the buyer brings a soil description or test and the supplier picks the diameter and length from its load table. Pull-out, sideways and downward capacity all depend on soil type and embedded length. A soil check, an on-site test screw or the supplier's load table for that soil gives the working number.
Catalogue screw length typically runs from under 1 m to around 3 m, and shaft diameters typically from around 60 mm to around 114 mm. Each supplier publishes its own diameter and length pairs in a size table, and the load table beside it shows which pair suits which soil. Short, slim screws usually carry a single pole, while longer ones go under tilt-leg frames and exposed sites.
The same pole on two different sites can need two different screws. A camera or sensor pole on firm clay and the same pole on loose sand read off different rows of the load table, which is why the soil description comes before any size is named.
The card below lists the five inputs that fix a ground screw specification.
For a pole mount, the screw head or sleeve has to match the pole outside diameter. The LinkSolar pole mount kit fits poles from 50.8 to 114.3 mm (2.0 to 4.5 in) outside diameter, so measure the pole itself rather than reading the nominal pipe size. The pole mount collection also calls for a pole with adequate diameter, wall thickness and foundation for the loads the mount and the module maker specify.
For a tilt-leg array, one screw under each foot plate is a common layout, with the leg bolted to the screw head. LinkSolar lists tilt legs keyed to panel frame size, because the leg chart follows frame dimensions rather than wattage. The tilt collection asks for frames to be fixed into structural members or rated anchors, and on open ground a screw chosen from the supplier's load table fills that role.
In frost-prone ground the helix typically sits below the local frost depth. The local building office or a geotechnical report gives that depth for the site, and the supplier then picks a length that reaches it.
Galvanized ground screws: which coating lasts, and why are some green?
Most metal ground screws are hot-dip galvanized steel, and a green finish is a color topcoat some makers add, which by itself says nothing about corrosion life. The coating that lasts is the one with a written specification covering the shaft, the helix and the head.
According to the American Galvanizers Association, in a page last updated in May 2022, hot-dip galvanizing means dipping fabricated steel into a kettle of molten zinc. The iron in the steel reacts with the zinc and forms a tightly bonded alloy coating. Because the dip comes after fabrication, it matters whether the helix and head were welded on before the screw went into the zinc.
Zinc is one of two common coatings. According to the Geoengineer.org page on helical piles, a zinc or polymer powder coating can be applied against corrosion, and gravelly soils can damage protective coatings. On a stony site, ask how the coating holds up during driving.
A green or other colored ground screw typically carries a powder or paint topcoat that some makers apply over the zinc or in place of it. Where it replaces the zinc, the topcoat alone protects the steel, so confirm which one you are buying.
Ask these on the quote:
- Coating type: hot-dip zinc coating, polymer powder coating, or zinc with a color topcoat over it.
- Coated after welding: whether the helix and head were welded on before the screw was galvanized.
- Topcoat: what the color layer is made of and whether zinc sits underneath it.
Ask the supplier for the coating specification and test report for the batch you order.
The screw is steel, while the pole kit or tilt legs above it are often aluminum. Where the two metals meet, use stainless hardware with an isolation washer or pad. LinkSolar's brackets use stainless hardware, and the guide to aluminium bracket material and finish covers the frame side of the joint.
How do you install a ground screw for a solar mount?
A ground screw for a solar mount is installed in six steps: locate buried services, mark the screw positions, drive each screw by rotation, watch the torque as it goes in, level the heads, then bolt the pole or legs on. Small screws for a single pole are often set with a hand-held or light rotary driver. Array-scale screws are set with a drive head mounted on a machine.
- Call the utility locate service: Have buried power, water, gas and data lines marked on the ground before any screw goes in.
- Mark the screw positions: Transfer the foot pattern of the pole base or tilt legs to the ground so each screw lands under a mounting point.
- Start each screw plumb and drive it by rotation: Keep the shaft vertical through the first turns, and drill a pilot hole first where rock or buried cobbles block the tip.
- Watch the torque as the screw goes down: Stop and contact the supplier if the screw refuses well short of its planned length.
- Set and level the heads: Bring every head level with the others in the group and check it with a spirit level so the frame sits square.
- Bolt on the pole or legs and re-check: Fix the mount to the heads, then check clamp and bolt tightness again after the first period of wind exposure.
Torque is the on-site record of how firmly each screw sits. According to a 2019 Iowa DOT helical pile specification, installers log torque with a calibrated torque indicator during installation (Iowa DOT Special Provisions for Helical Pile). On a small solar job, a written reading for each screw gives the supplier a record to compare with its load table for that soil.
Early refusal is the most common surprise in step 4. According to Geoengineer.org's page on helical piles, early refusal can occur in expansive soils. Send the supplier the soil description and the point where the screw stopped, and it can match a screw size to that ground.
Where the site calls for a concrete footing instead, the pole-mount installation guide covers sizing a pole and its footing step by step. LinkSolar supplies the pole kits, tilt legs and stainless hardware that bolt onto the screw heads in step 6.
How much do ground screws cost, and what goes into a quote?
Ground screw prices vary by size, coating, head type, quantity and the soil at the site, so the useful figure is a quote for each screw size your site needs. A supplier picks the size from its load table once it knows the soil and the load, and the price follows that size. A complete first message lets the supplier quote the right screw on the first reply.
- Soil description or test: The soil type at each spot, or a soil test or geotechnical report if one exists, sets the shaft diameter and length.
- Panel count and frame size: The number of panels and their frame dimensions tell the supplier how much load each screw carries.
- Pole outside diameter or leg foot pattern: A measured pole diameter, or the hole pattern of the tilt-leg foot plates, fixes what the screw head has to accept.
- Head type: A flange, U-bracket or threaded adaptor on top decides how the pole or leg bolts on.
- Coating wanted: Hot-dip zinc alone or zinc with a colour topcoat changes the finishing step and the price.
- Site exposure: An open field, a hilltop or a sheltered yard sets how much wind load the frame passes down to each screw.
- Number of sites: The site count and screws per site set the quantity the price per size is based on.
LinkSolar supplies the above-ground half, the brackets, pole kits and tilt legs, and helps put the foundation spec together with it so the screw heads and adaptors match. LinkSolar lists brackets and stainless hardware for the frame above ground across six mounting methods. Send the panel model, mounting surface and quantity along with the list above, and the reply is a bill of materials with load ratings against it.
An odd pole size or a screw head that no stock bracket fits is the normal starting point for an adaptor plate. The guide to adaptor plates for odd pole and screw heads covers how those parts are specified. Where panels run along a rail, rail kits that bolt onto a post or leg sit between the screw head and the frames.
FAQ: helix ground screws
What is a ground screw?
A ground screw is a steel shaft with a helical blade near its tip that is turned into the soil to anchor a solar pole, tilt leg or small frame without concrete. The head on top, a flange, U-bracket or threaded adaptor, is where the pole or leg bolts on.
The blade bears on the soil around and above it, so the holding capacity comes from the soil at the site and the embedded length. Most metal ground screws are hot-dip galvanized steel, sometimes with a coloured topcoat.
How much do ground screws cost?
Ground screw prices vary with shaft diameter and length, coating, head type, order quantity and the soil the screws must go into, so no single list price fits every site. The useful figure is a quote per screw size, priced against your soil description and load.
Give the supplier the soil type, panel count and frame size, the pole outside diameter or leg foot pattern, and the number of sites.
Are ground screws better than concrete?
Ground screws are faster than concrete footings for most small solar mounts, because they take the mount the same day, need no digging or curing and can be backed out and reused. A concrete footing still suits a permanent pole on ground that digs cleanly, or a spot where buried rock stops a screw early.
The soil decides between the two. A soil check or the supplier's load table shows whether a screw will hold the mount.
Can you install a ground screw by hand?
Small ground screws for single poles are often installed by hand, with a driver bar through the head or a hand-held rotary driver. Longer and wider screws for tilt-leg frames and array rows typically need a machine-mounted drive head.
Keep the screw plumb as it starts, and stop to ask the supplier if it refuses early, since rocky ground may need a pilot hole. Call the local utility locate service before any driving.
Next step
The size table lists the screw; does your soil match it? Send the soil description, the panel frame size and the pole outside diameter or leg foot pattern, then request a quote for the screws and the mount together through custom panel and mounting quotes. LinkSolar sources the pole kits, tilt legs and brackets that sit above the screw, so the heads and adaptors are matched in one quote.