Siemens has agreed a further strategic investment in Skeleton Technologies alongside an exclusive partnership to supply high-power supercapacitor systems to the global data centre market. The agreement will support Skeleton’s planned expansion of manufacturing and research operations in the United States, including domestic production of supercapacitor cells and complete electrical storage systems.
The transaction was announced on 14 October, with Skeleton identifying a nine-figure investment round and a company valuation exceeding $1 billion. It intends to invest more than $200 million in operational expansion and research and development activities in Silicon Valley, targeting demand from operators building high-density artificial intelligence computing facilities.
Siemens will receive exclusive rights to sell and scale Skeleton’s products in the data centre market. The companies intend to integrate high-power storage into electrical infrastructure serving computing equipment, extending Siemens’ offering from the utility connection to the distribution systems within data centre buildings.
The investment extends an established relationship rather than creating a new partnership from the outset. Siemens began supporting Skeleton’s manufacturing development in 2022 and participated as an investor in 2023, while Siemens’ industrial technology business contributed to the design and automation of the company’s Leipzig SuperFactory in Germany.
The latest agreement adds a defined commercial arrangement for the data centre sector. Completion remains subject to customary formalities, and Siemens has not disclosed the value of its individual investment or the percentage ownership interest it will hold.
Skeleton develops supercapacitor systems using its proprietary Curved Graphene electrode material, associated power electronics and system control technology. The devices are intended to absorb and release electrical energy at high rates, making them suitable for repeated short-duration power events.
Supercapacitors differ from batteries in the mechanisms used to store electrical energy. Their electrodes can accumulate charge at the interface between an electrode surface and an electrolyte, allowing rapid charging and discharging without relying exclusively on the slower chemical processes associated with conventional battery storage.
The resulting characteristics favour high power output over extended discharge duration. A supercapacitor can respond quickly to changes in electrical demand, but it generally stores less energy than a battery of comparable size or mass designed to supply a load for a longer period.
This distinction is important within data centres, where different electrical systems address different operating requirements. Uninterruptible power supplies and backup generation protect against loss of electricity supply, while high-power buffering can reduce the effects of rapid changes in demand during otherwise normal operation.
Large AI computing installations contain thousands of processors operating on connected workloads. Their electrical consumption changes as processing tasks begin, complete or move between stages, and synchronised behaviour across a large number of devices can produce substantial changes in total demand.
Siemens says those fluctuations can begin within milliseconds and accumulate into changes at megawatt scale over seconds. The electrical infrastructure must accommodate them while maintaining the voltage, power quality and operating conditions required by computing equipment.
Rapid changes in load affect more than the devices consuming electricity. Power converters, transformers, conductors and the upstream network respond to variations in current and the rate at which electricity is required, with their performance governed by equipment ratings, control systems and available supply capacity.
Skeleton’s proposed arrangement places fast-response storage close to the computing load. When electrical demand rises suddenly, the supercapacitor system can provide additional power for a short period. When demand falls, it can absorb energy and prepare for the next change.
The operation requires power electronic converters capable of directing energy between the storage system and the electrical distribution network. Controls must monitor the available stored energy, respond to changing load conditions and coordinate with the protection arrangements of the connected installation.
Managing rapid fluctuations locally can reduce the magnitude of changes experienced by upstream equipment. The benefit depends on the size and duration of the load events, the storage capacity installed and the performance of the electrical controls.
Supercapacitors cannot support a sustained high-power demand indefinitely. Their ability to contribute power is limited by available stored energy, making system sizing an important part of determining which disturbances can be managed and how quickly the equipment must recharge.
Skeleton is also targeting power quality problems associated with rapidly changing electronic loads. Power converters can generate harmonics, which are components of electrical current or voltage at frequencies related to the fundamental supply frequency. Their effects depend on the equipment involved and the characteristics of the electrical distribution system.
Appropriate converter design and control can help manage certain power quality disturbances, although a supercapacitor installation does not automatically remove all harmonics from a facility. The operating results must be assessed against the specific network configuration and load behaviour.
Skeleton claims its systems can produce energy savings of up to 40% and double-digit improvements in GPU performance under suitable operating conditions. These are company performance claims rather than independently verified results applicable to every data centre. The October announcement does not provide a complete test methodology or baseline against which the figures can be assessed.
The companies intend to support existing alternating current installations and retrofit projects while developing products compatible with future 800V direct current architectures. The latter approach changes how electrical energy is distributed to computing equipment, potentially reducing current for a given power requirement.
Higher distribution voltage can reduce conductor losses, but it also changes requirements for insulation, switching, protection and the electrical interfaces used by connected equipment. Adoption of an 800V DC architecture would therefore depend on the design of the complete installation rather than a simple replacement of its energy storage devices.
Manufacturing expansion is a central element of the agreement. Skeleton’s planned US operations will extend from supercapacitor cell production through to complete high-power systems, reducing the distance between selected manufacturing activities and major customers in the American computing infrastructure market.
Cell production involves controlling electrode materials, assembly conditions and electrical characteristics so that completed devices deliver repeatable performance. Differences in internal resistance, capacitance and other parameters can influence how individual cells behave when incorporated into larger assemblies.
Modules and systems also require suitable connections, monitoring equipment, power conversion electronics and arrangements for managing operating temperature. High current operation produces losses that must be considered during mechanical and electrical design, particularly where equipment is installed in densely populated electrical rooms.
Moving to higher production volumes increases the importance of stable manufacturing processes and repeatable testing. Components must meet their specified characteristics across successive batches, while final assemblies need verification that their control and protection systems operate correctly.
Skeleton’s existing European manufacturing operations provide experience relevant to the new expansion. Its Leipzig SuperFactory, opened in 2025, uses manufacturing automation developed with Siemens technology, although the US investment does not establish that an identical production line will be installed in Silicon Valley.
The new facilities have not been assigned a published annual output target, and the companies have not specified when domestic US cell manufacturing will enter operation. The announced $200 million-plus programme covers expansion and research activities rather than an itemised budget for a single production plant.
Siemens intends to use its electrical infrastructure business to integrate Skeleton’s systems into customer installations and provide a route to commercial deployment. Skeleton will continue developing and manufacturing its storage technology while the companies coordinate their product offerings for the data centre market.
The partnership connects a planned manufacturing expansion with equipment intended to address rapid electrical demand changes in AI computing facilities. Its contribution will depend on the completion of the investment arrangements, establishment of additional production capacity and verified performance of the storage systems within operating electrical infrastructure.
