Siemens and Reinhausen turn up the voltage for hungry AI racks

Siemens and fellow German engineering biz Reinhausen are developing a solid-state transformer (SST) to deliver 800-volt DC power directly to increasingly dense AI datacenter racks.

As AI hardware grows hotter and hungrier, server farm operators are looking to overhaul how power moves through their data halls.

One approach, favored by Nvidia and other industry heavyweights, is distribution at 800 VDC.

The two electrical enterprises are therefore developing a modular SST capable of converting medium-voltage AC at up to 36 kV into a stable 800 VDC output for downstream distribution.

Siemens says that the SST will provide a compact, galvanically isolated alternative to conventional multistage AC-to-DC power conversion architectures, reducing intermediate conversion stages and enabling more efficient delivery to high-density AI infrastructure.

According to Reinhausen, datacenters supporting AI workloads are among the industry's most demanding power consumers.

Sudden load spikes can strain servers, storage, and cooling systems, reducing performance and potentially causing outages.

"Our technology enables AI datacenters to operate with the efficiency and reliability they require," said Reinhausen managing director Wilfried Breuer.

"Solid-state transformers are critical for these large and power intensive structures.

They enable higher efficiency, direct grid-to-rack DC conversion, and a reduced footprint.

This collaboration will further strengthen our leading position in the electrification of datacenters," commented Siemens CEO of Electrification and Automation, Stephan May.

As The Register reported late last year, Nvidia sees 800 VDC power distribution as the way forward for AI infrastructure, and says the shift will be necessary to support IT racks drawing 1 MW or more.

That may sound far-fetched when average rack density has only just passed 11 kW, according to Uptime Institute, but hyperscalers such as Google are already planning for megawatt-scale racks.

Nvidia has also developed its own MGX-compatible 800 VDC power rack, which it says will arrive "in the second half of 2026." Siemens and Reinhausen said that they intend to industrialize their datacenter SST, but did not say when it would become commercially available.