Liquid Cooling Moves Into the Power Side
When 10 kV AC begins converting directly to 800V DC, the heat sources for liquid cooling extend beyond GPUs and servers to high-power power-electronics equipment. Eaton's MV SST solid-state transformer 2.0, released in June 2026, is a clear signal: liquid cooling is entering the data center power side.
The Eaton unit converts 10 kV medium-voltage AC directly to 800V DC at 2.5 MW capacity with roughly 98.3%–98.5% efficiency, using all-SiC power modules, a high-frequency isolation transformer and a liquid-cooled structure for outdoor and prefabricated deployment. Even at 98.5% efficiency, a 2.5 MW device still dissipates nearly 38 kW of loss — heat now concentrated in a footprint far smaller than a conventional transformer.
Why the Power Side Needs Its Own Cooling Architecture
SST liquid cooling will not simply copy the server CDU architecture. Instead, it forms three distinct layers:
| Layer | Heat Source | Liquid Cooling Form |
|---|---|---|
| Device-level | SiC modules, high-frequency transformer, inductors | Cold plates, integrated flow channels, thermal/insulation materials |
| Equipment-level | SST power cabinet, conversion unit | Built-in pumps, manifolds, filters, sensors, closed loop |
| Facility-level | Power room, outdoor equipment zone | Liquid-to-liquid heat exchangers, dry coolers, facility water interface |
Unlike server cooling, SST liquid cooling must first satisfy the insulation, safety and maintenance requirements of high-voltage electrical equipment. Early projects favor an independent closed loop — the SST handles pumping, distribution and monitoring internally, then rejects heat to outdoor dry coolers or facility water through a liquid-to-liquid heat exchanger.
Chillers and CDUs Scale Up for High-Density AI
On the thermal side, Schneider Electric's Uniflair XCA series provides air-cooled and free-cooling chillers purpose-built for high-density liquid-cooled AI data centers. The platform integrates oil-free centrifugal compressors with magnetic-bearing technology and built-in variable-speed drives, achieving an energy efficiency ratio (EER) up to 4.66 with six units ranging from 1,200 kW to 2,500 kW. The free-cooling XCAF model tolerates water outlet temperatures up to 33°C, enabling up to 60% energy reduction compared with purely mechanical cooling in mild climates.
At the same time, MW-class CDUs are becoming the norm as rack power rises. Suppliers are no longer judged only on cooling capacity, flow and redundancy — they must also prove predictable control under rapid load swings, fault-state reporting and coordination with energy storage, server derating and the DCIM layer.
Prefabricated Cooling Cuts Total Cost by 30%
Prefabricated modular cooling stations are reshaping project economics. By moving pipe welding, insulation, wiring, pressure testing and hydraulic balancing into the factory, on-site work shrinks to 7–15 days of lifting, docking and commissioning — down from 3–6 months. Material waste falls from 15% to under 3%, on-site labor drops by 70%, and annual energy consumption declines by over 12% through precise hydraulic balancing. Combined with lower construction, operation and residual-value advantages, the full lifecycle cost savings reach approximately 30%.
The direction is unmistakable: as AI infrastructure moves from stacking equipment to configuring by compute unit, the competitive unit shifts from a single device to a whole coordinated system. Liquid cooling's next growth engine is moving from compute equipment into power-delivery equipment — and suppliers who can define the interface, control boundary and system integration will hold the advantage.
