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

Speed of execution. A concrete foundation requires a curing break (typically 21–28 days) before it can bear a full load. A ground screw is load-bearing immediately after installation — the container can be placed on the same day.

Exact load capacity documentation. The telematics unit records the torque and depth profile 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, verifiable foundation load-bearing capacity 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. Concrete pouring is sensitive to temperature and precipitation. Screw driving takes place independently of weather conditions within the machine's normal operating temperature range.

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

1. Geotechnical survey 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 footings—a deviation of even a few centimeters can make installation impossible. The setting out is carried out by a surveyor.
3. Test drilling and torque verification. The first screws are driven in as a test set. The machine's telematics unit records the torque versus depth curve—if the subgrade 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 (max. deviation according to the project). The telemetric record of each point is archived as part of the construction documentation.
5. Assembly of bearing heads and flatness inspection. Bearing heads or steel profiles are fitted onto the screws, and a surveyor verifies the flatness of the entire assembly within the container manufacturer's tolerance. After approval, the container can be installed.

The investor planned to supplement the existing photovoltaic power plant with a battery energy 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.

The geotechnical survey confirmed medium-dense silty-sandy soil suitable for standard screwing. The implementation team deployed the B80 machine, drove a test set of screws on-site on the first day, and compared the measured torque with the structural engineer's expectations. After confirming conformity, the installation of the entire assembly followed, including the supporting steel frames for the containers.

The entire foundation phase (screwing in + installation of support heads) was completed within days, without any technological break for concrete curing — the containers could be installed immediately after completion and flatness inspection. The telemetric record of each screw served as the basis for final approval as well as part of the documentation for investment insurance.