Ground Screws Open Up More Sites for Ground Mount


Ground screws turn inaccessible or difficult sites into potential locations for ground mount solar installations. Already a leader in pile-driven, cast-in-place, and ballasted foundations, Unirac now offers these versatile new tools and 25-year warranties to go with them.

So, what is a ground screw, exactly?

Think of an ordinary wood screw—the long, tapered, pointy kind with threads—but imagine it a lot bigger (four feet or longer) and you’ll have a pretty good idea of what a ground screw looks like. It’s a type of foundation (atop which are connected the structural beams and module hardware of a system) that has a continuous helix wrapped around a round pipe. They are generally hollow, unlike wood screws. If you’ve seen helical piles, ground screws are similar, but helical piles have a single helix or a helix at two or three points along the structure and are not continuous.

There are places where ground screws are an ideal option, such as locations with limited site access and areas where the soils have denser material, very weak bedrock, or gravels. Denser, harder soils may refuse standard pile-driven foundations, but ground screws will have a better chance of penetration, and since they don’t have to go as deep, they have a higher probability of success.

Some especially dense soils—those made up of cobbles, or those made of weak- to moderate-strength bedrock—may beat back even ground screws, but ground screws will still have the best chance of working in specific environments.

Ground screws can be used to gain higher vertical capacities at shallow depths, often require no pile testing or geotechnical investigation, can be installed with commonly available equipment, and can be installed in limited-access areas (e.g., sites without paved roads).

What is Unirac’s Ground Screw?

Unirac now offers 68 mm-diameter ground screws in two lengths, 1600 mm and 2000 mm. They are made from high-strength steel with a zinc galvanization coating for corrosion protection. These ground screws can be purchased by the pallet (a count of 163 screws). Please see the Unirac Master Price List for part number and pricing information at: Ground screws are available now with Unirac’s industry-leading lead times.

The screws connect with Unirac’s proven Unirac Large Array (ULA) ground mount system, already designed for maximum flexibility in install environments.

ULA, including the new ground screws, will soon be integrated into Unirac’s user-friendly online design tool, U-builder, allowing customers to get the benefits of the new foundations quickly.


For installation, a mini excavator or a skid-steer loader (such as a small backhoe or Bobcat) can be used. A two-person auger, seesaw auger, or high-impact drill may be possible in some settings. Even farm tractors can be employed. A high-torque, low-speed hydraulic motor attachment and drive head adapter are also required. All of these are readily available.

Installers comfortable with other ground mount foundations won’t find the process challenging, according to Unirac Soils Engineer Jon Schermerhorn. “Once you’ve identified a site as a good location,” Schermerhorn says, “the screws themselves go in really quickly and easily. All the equipment is small-scale stuff that lots of people are familiar with.”

If you’re ready to get started on a whole new range of sites, you can contact your local distributor, or if you have questions, please call Unirac Commercial Services at 505-248-2701 or email