The solid-state transformer: 98% efficient, a tenth of the core

The wait for a large grid transformer now runs to five years, and without one neither a new power plant nor a data centre can be connected. In August 2026 the New York Power Authority and EPRI tested a one-megawatt solid-state transformer under realistic utility conditions at EPRI's test site. The prototype reached roughly 98% efficiency with a magnetic core an order of magnitude smaller than a conventional one.

Key takeaways

• The 1 MW prototype: around 98% efficiency against about 96% for a conventional transformer plus rectifier
• The magnetic core can be roughly ten times smaller at the same capacity
• The device was built in Srdjan Lukic's lab at North Carolina State University
• The prototype runs at about 15,000 volts, while transmission lines run at hundreds of thousands
• On 21 October 2026 Vantage reserved more than 1 GW of Heron Link manufacturing capacity for its data centre campuses

Let us picture a situation

Power from a US solar farm leaves the inverter at around 480 volts, enters the transmission line at 115,000 volts to cross hundreds of kilometres, and must finally feed an outlet at 120 and 240 volts.

That is four or more voltage changes on one route, each needing a separate, heavy device with a special-steel core and miles of copper wire.

But here is the problem: the wait for such a device now runs up to five years.

It is that queue the solid-state transformer is stepping into.

How does a conventional transformer work?

Moving power is not perfectly efficient — some is lost as heat in the lines. The higher the voltage, the lower the current and the smaller the losses. Stepping voltage up and down is therefore a core function of the grid.

A conventional transformer's core is grain-oriented electrical steel, with copper coils at either end. The number of turns on each side sets the voltage: more turns on the secondary steps it up, fewer steps it down.

Current in the input coil creates a magnetic field in the core, which induces a voltage in the coil on the other side — the phenomenon is called magnetic induction. Galvanic isolation comes with it: no direct electrical path runs through the device, which limits how far disturbances spread.

Transformers form the backbone of electricity transmission and distribution.

Srdjan Lukic, professor of electrical and computer engineering at North Carolina State University, speaking to MIT Technology Review.

The problem, as Lukic notes, is that today's transformers are big and bulky, and replacing them is difficult and expensive.

What does the solid-state version change?

A solid-state transformer adds power electronics to that layout — semiconductors that convert and control current. The key difference is frequency: a conventional device runs at the frequency of the grid it is attached to, while a solid-state one sets that frequency itself.

This is a simplified chain for a typical design, not a schematic of one specific device.

Why can the core be smaller? Because the semiconductors give such control over frequency and stability that the magnetic stage need not be massive. Per Lukic, some designs come in at one-tenth the size of a conventional equivalent at the same capacity.

The second gain is systemic. Many transformers today do only one thing: change voltage. A solid-state one also absorbs the jobs of rectifiers and inverters, which convert AC to DC and back. Fewer devices means less floor space and fewer losses.

What do these names mean?

A few terms in this account decide what is actually new here.

• Grain-oriented electrical steel — steel processed to channel a magnetic field in one direction. A supply bottleneck.
• Magnetic induction — energy transfer through a magnetic field, with no electrical connection between coils.
• Galvanic isolation — no direct current path between input and output. A fuse against disturbances.
• Power electronics — semiconductor circuits controlling large power flows. Here they take over part of the core's work.
• Silicon carbide (SiC) — a semiconductor withstanding higher voltages and temperatures than silicon. The switch material here.
• 800 VDC — 800 volts direct current, the emerging distribution standard in new AI server racks.

Together these terms show the real trade: mass of copper and steel for silicon and control.

Why not simply build more conventional transformers?

The money has already gone in. Per Benjamin Boucher, a supply chain analyst at Wood Mackenzie, grid-equipment makers have put $1.7 billion into the US supply chain for high-voltage power transformers and $1.3 billion for distribution transformers.

That is not keeping pace with the grid's growth, because standing up new production is highly technical and needs specialised labour — facilities announced years ago are still years from opening. Wait times for large conventional transformers — those needed to connect new power plants, transmission lines and high-demand sites including data centres — stretch as long as five years.

Transformers have become one of the biggest bottlenecks for utilities, generation developers, and even data centers.

Benjamin Boucher, supply chain analyst at Wood Mackenzie, speaking to MIT Technology Review.

There is a second problem production scale does not solve: power electronics have more failure modes than a conventional core. In a traditional device a failure usually means taking the whole unit offline. So Heron Power designs modularly — many small devices working together, and one failing does not stop the rest.

Is it live yet?

This is a tested prototype and first manufacturing agreements, not hardware swapped into the grid. The 1 MW test was, per Lukic, the first of its kind at that capacity. The prototype runs at about 15,000 volts — larger data centres need more, transmission lines hundreds of thousands.

The efficiency difference looks modest but matters: the prototype lost 2% of the energy fed in, against around 4% for a conventional transformer plus rectifier — half the losses.

First agreements

The most concrete commercial move is an agreement dated 21 October 2026. Vantage reserved more than 1 GW of Heron Link capacity for its data centre campuses. Heron Link converts medium-voltage grid power directly to 800 VDC with integrated storage, targeting over 98.5% efficiency. The company participates in NVIDIA's 800 VDC MGX ecosystem.

By partnering with Vantage to deploy more than a gigawatt of Heron Links in data centers, we will move 800 VDC from a reference architecture concept to a repeatable, deployed platform.

Drew Baglino, founder and CEO of Heron Power, in the company's press release.

Heron Power is building a $100 million factory in California, due to start production in 2027 and reach 40 gigawatts of transformers per year in 2029.

Why does it matter?

What limits AI's build-out today is not only the number of accelerators but the number of devices delivering power to them. The solid-state version changes the nature of that limit: instead of a queue for steel and copper, there is a dependence on the supply of power semiconductors, whose production ramps on a different timescale.

What comes next?

• The California factory reaches full rate only in 2029 — until then the supply of solid-state transformers stays a fraction of what the grid needs.
• Ten megawatt-hours of batteries at the Scotts Valley headquarters are to be tested with Heron transformers soon, with a pilot at a nearby solar farm also planned.
• High-voltage devices for power plants and transmission lines are, per Lukic, this technology's "holy grail" — they cannot be built without new materials and designs.

Sources

• MIT Technology Review — How solid-state transformers could help power the AI boom
• Heron Power Electronics — Vantage and Heron Power Electronics Announce Gigawatt-Scale 800 VDC Agreement to Accelerate AI Infrastructure Delivery