SST Revolution: From Data Centers to Grids

Abstract: On October 16, 2025, NVIDIA released the white paper "800 VDC Architecture for Next-Generation AI Infrastructure", highlighting that with the rapid advancement of large AI models and continuous iteration of CPU and GPU technologies, the power per rack has increased from 10 kW in 2020 to 150 kW in 2025, and is projected to reach 1 MW per rack by 2028. For such megawatt-level power loads and extreme power densities, traditional low-voltage AC distribution systems are no longer sufficient. Therefore, the white paper proposes upgrading from conventional 415V AC power systems to an 800V DC distribution architecture, sparking significant interest in a key enabling technology—Solid-State Transformers (SST).

Advantages for data center projects: The Solid-State Transformer (SST) can directly convert from grid AC 10 kV to DC 800 V, offering advantages such as compact size, lightweight design, and integrated functions including reactive power compensation and power quality management. HVDC systems can eliminate the need for many intermediate devices, such as UPS units.

From the data center power distribution architecture, it is clear that transitioning to HVDC (High-Voltage Direct Current) offers numerous advantages, including:

• Higher voltage reduces current, directly decreasing the required amount of copper cabling or busbars.

• Significant reduction in distribution equipment, eliminating the need for numerous traditional UPS units.

• Substantial reduction in auxiliary facility space— for megawatt-scale per-rack data centers, conventional electrical rooms would otherwise occupy far more area than the main server rooms.

• Improved conversion efficiency: SSTs themselves are significantly more efficient than traditional transformers, and with far fewer power conversion stages in the overall system architecture, energy losses are considerably reduced.

As shown in the figure above, energy storage battery cabinets can be directly connected to the DC 800V bus ("battery direct-hanging"), thereby reducing intermediate power losses and eliminating the cost of inverters. Similarly, wind and solar power can also be integrated directly via DC/DC converters. This advancement holds significant importance for promoting green data centers.

SSTs Are Not Limited to Data Centers: The "Dual Carbon" goals (carbon peak by 2030, carbon neutrality by 2060) have elevated energy efficiency in industrial and civilian sectors to a new level. In general industrial and commercial buildings, SSTs can also be widely applied. When the secondary output is AC, SSTs can directly upgrade and replace traditional transformers. When the secondary voltage is high-voltage DC, it will be a transformative step for building-level DC power distribution. For example, in the current promotion of "Photovoltaic-Storage-Direct-Flexible" (PSDF) technology, from the transformer to the busbar, centralized or distributed AC/DC bidirectional inverters are no longer needed, enabling seamless building-wide DC power distribution.

Regarding concerns about the maturity of DC-powered end-use equipment, such devices are now increasingly mature, including:

• Electric Vehicles (EVs): EV platforms have evolved from 400VDC to 800VDC and even higher. These systems emphasize fast charging, high power density, reduced copper cabling, and feature efficient rectifiers, high-current portable cables, advanced safety connectors, and fault-tolerant protection schemes. High-voltage DC enables vehicles to charge or even sell power back to the grid (V2G) through bidirectional charging stations.

• Photovoltaics (PV): Large-scale solar farms typically operate at 1000–1500VDC, leveraging mature DC-side switchgear, fuses, and combiner boxes to connect directly to DC distribution systems.

• Energy Storage (ES): Commercial and industrial energy storage systems can be directly connected to DC 800V grids.

• HVAC and other power equipment: Major Chinese HVAC manufacturers have already launched 375V DC-compatible units.

• LED lighting, outlets, and other end devices: Corresponding DC products are now being widely deployed.

• Regarding SST transformers, domestic equipment manufacturers have already launched products, which are being applied and promoted in various scenarios such as data centers and energy-saving retrofits.