What an SST is
A solid-state transformer (SST) replaces the conventional 50 Hz transformer with silicon carbide power electronics. It takes 10-35 kV grid voltage, converts it at high frequency and delivers 800 V direct current straight to the hall bus. Instead of a bulky copper core, the work is done by a compact high-frequency transformer and several converter stages.
Why it matters for AI data centers
A conventional site power chain has five stages: the grid, a transformer, the main switchboard, a double-conversion UPS and the rack power supplies. Each stage loses energy and takes up space. An accelerator rack draws 120-140 kW, and at that density the copper of 0.4 kV busbars and the size of the electrical room become as much of a constraint as cooling.
Accelerator manufacturers have announced a move to 800 V DC rack power from 2027. High-voltage direct current cuts currents and busbar cross-sections several times over, and an SST naturally delivers exactly this kind of bus.
Power chain today
- 10-35 kV grid
- 50 Hz transformer
- 0.4 kV main switchboard
- Double-conversion UPS
- Rack power supplies
Power chain tomorrow
- 10-35 kV grid
- Solid-state transformer
- 800 V DC bus
- Racks
What it delivers
According to estimates from early projects, an SST saves up to half of the electrical room floor space and 3-5 percent of energy compared with a "transformer - UPS" chain. Power electronics are also controllable: they limit the rate of power change, compensate reactive power and work directly with storage on the DC bus.
Where the technology stands today
The first commercial units rated at 2-3 MW appeared in 2025-2026. Safety and grid connection standards are still taking shape, operating experience is measured in months, and the price is still 2-3 times higher than the familiar transformer and UPS combination. For a customer who needs a site this year, this is a technology risk not worth taking on.
The OS Power position
We design sites ready for 800 V DC and SST: we reserve space, cable routes and busbars so that the transition does not require replacing transformers and switchboards. Today we install proven solutions: dry-type transformers, storage on the bus and a supercapacitor buffer in front of the racks. We will offer solid-state transformers to customers once the technology is certified and in volume production.
OS Power storage on the bus already handles some of the tasks SST is being developed for: it shaves peaks, absorbs GPU load pulses and, with a variable load profile, reduces the required grid connection capacity by 20-50 percent (for training clusters the effect is determined by calculation on the hourly load profile). How site power is designed.