Battery energy storage systems on ground screws — foundations for BESS containers

Speed of implementation. A concrete foundation requires a curing period (typically 21–28 days) before it can bear full loads. A ground screw can be loaded immediately after installation — the container can be placed on the same day.

Precise load capacity documentation. The telematics unit records the course of torque and depth for each screw. This record serves as a basis for both the structural engineer and the insurance company — for an investment in the order of millions to tens of millions of crowns per BESS unit, the verifiable load-bearing capacity of the foundation is an important due diligence document.

Reversibility. A number of BESS projects run on land with a limited lease period (15–25 years) or on agricultural land where the investor guarantees the return of the land to its original state. Ground screws can be unscrewed without a trace after operation ends — concrete must be demolished and hauled away.

Weather independence. Concreting is sensitive to temperature and precipitation. Screwing is carried out independently of climatic conditions within the normal operating temperature range of the machine.

Work on uneven or compacted ground. BESS containers are often placed on the edges of existing industrial sites or on brownfield land where subsoil homogeneity is not guaranteed. Trial screwdriving with telemetry quickly reveals whether the length or diameter of the screw needs to be adjusted at a specific point.

1. Geotechnical site investigation and determination of point loads. Based on the container's technical data sheet and the site's geotechnical survey, the structural engineer will determine the required load-bearing capacity, length and diameter of the screw for each support point.
2. Layout design according to the structural grid. The placement of the screws must correspond precisely to the container's footings — a deviation of even a few centimetres can make installation impossible. The setting out is carried out by a surveyor.
3. Trial drilling and torque verification. The first screws are driven in as a test set. The machine's telematics unit records the torque vs depth profile — if the subsoil profile matches the survey assumptions, driving of the full assembly continues.
4. Drilling of the entire assembly with telemetry logging. Each screw is driven to the specified depth with verticality control (maximum deviation according to the design). A telemetry record of each point is archived as part of the construction documentation.
5. Assembly of bearing heads and flatness check. Support heads or steel profiles are fitted onto the screws, and a surveyor checks the flatness of the entire assembly within the container manufacturer's tolerance. Once approved, the container can be installed.

The investor planned to supplement the existing photovoltaic power plant with a battery storage system with a capacity in the order of single-digit MWh, located on an adjacent plot of land with a fifteen-year lease. The landlord's condition was the restoration of the land to its original state after the end of the lease — a concrete foundation would complicate this condition.

Geotechnical survey confirmed moderately compacted sandy-loam soil suitable for standard screwing. The implementation team deployed the B80 machine, installed the test set of screws on site on the first day and compared the measured torque with the structural engineer's prediction. After confirming the match, the installation of the entire assembly followed, including the load-bearing steel frames for the containers.

The entire foundation section (driving and installation of the load-bearing heads) was completed within days, without any technological break for concrete curing — the containers could be installed immediately after completion and flatness inspection. The telemetry record of each screw served as the basis for final building approval and as part of the documentation for investment insurance.