Solid-State Transformers: Measured Progress and Voltage Limits in Addressing AI Data Center Power Bottlenecks
The delivery wait time for large transformers on the U.S. power grid has extended to five years, becoming a critical constraint for connecting AI data centers. MIT Technology Review reports that solid-state transformers achieve approximately 98% efficiency and one-tenth the volume of traditional units through power semiconductors; their first megawatt-scale field test under real grid conditions was completed in August 2026 by the New York Power Authority and the Electric Power Research Institute (EPRI) at an EPRI facility. Heron Power has raised $140 million and is building a factory with an annual capacity of 40 gigawatts. However, current prototypes operate only at 15,000 volts, making them unable to replace high-voltage transformers required for transmission lines operating at hundreds of thousands of volts.
The expansion of AI data centers is encountering a subtle but increasingly urgent hardware bottleneck: transformers. Benjamin Boucher, a supply chain analyst at the energy research firm Wood Mackenzie, notes that the wait time for delivering large traditional transformers—needed to connect new power plants, transmit electricity over long distances, and serve high-demand sites like data centers—has stretched to five years.
The basic design of traditional transformers has remained largely unchanged for nearly a century: the core consists of grain-oriented electrical steel, with copper coils wound on either end, stepping voltage up or down through magnetic induction. Manufacturing these devices requires significant specialized labor and complex processes; even new production facilities announced years ago have struggled to come online. "Transformers have become one of the biggest bottlenecks for utilities, generation developers, and even data centers," Boucher said.
The concept behind solid-state transformers involves adding power semiconductors to the traditional magnetic induction framework. Srdjan Lukic, a professor of electrical and computer engineering at North Carolina State University, explained that solid-state transformers first convert incoming alternating current (AC) into direct current (DC), then use semiconductor switches made of materials like silicon carbide to convert it into high-frequency AC. A smaller magnetic core handles the voltage transformation before converting the power back to the required frequency. Because semiconductors allow precise control over current frequency and stability, the magnetic core can be reduced to about one-tenth the size of a traditional transformer while maintaining the same capacity.