900-V GaN Enters 1.25-MW Solid-State Transformer Development

Enphase Energy says one IQ solid-state transformer rack can deliver up to 1.25 MW from a 34.5-kV AC input, with 342 power modules built around Infineon Technologies' 900-V gallium-nitride bidirectional switches.

Why does Enphase trust GaN at megawatt scale?

Enphase already partnered with Infineon on 650-V GaN bidirectional-switch technology for its IQ9 microinverters. The 900-V GaN has now passed testing and entered integration into Enphase's IQ SST product development, with production qualification to follow closely.

Enphase CTO Hans van Antwerpen said: "GaN is not new to us. It has been running in Enphase’s IQ9 microinverters in the field, and that experience has given us confidence in deploying the technology in megawatt-scale systems." That field history provides the basis for Enphase's larger SST design.

He added: "Moving to 900 V gives us more voltage headroom while retaining the benefits of high-frequency switching. It allows us to remove converter stages from the system and reduce the number of components in the power path, which translates to higher efficiency, higher power density, and improved system reliability."

The mechanism is direct: more voltage per device can remove converter stages and reduce parts in the power path. Enphase is moving GaN experience from microinverters into a claimed 1.25-MW rack architecture, making production qualification the next commercial gate.

How does a solid-state transformer serve an AI data center?

Like conventional transformers, solid-state transformers sit at the front of a facility's power distribution system. They convert medium-voltage grid electricity, typically 13.2 or 34.5 kV, into low-voltage power, generally 480-V AC. Their role is therefore familiar, even when their internal operation is not.

Instead of massive iron cores and copper windings, solid-state transformers use power semiconductors and digital control. This lets them supply the ±400- to 800-V DC bus increasingly favored by AI server racks.

Silicon-carbide or gallium-nitride devices allow high-frequency switching, which can make an SST more efficient and compact than a line-frequency transformer. That operation also supports faster responses to changing loads and more precise regulation of power flow. In short, an SST replaces a large passive transformer with controlled semiconductor conversion.

Why do SiC and GaN play different roles?

Silicon carbide has emerged as the leading technology in multilevel power converters because it can handle higher voltages. That voltage capability reduces the number of conversion stages inside an SST.

GaN offers faster switching speeds and higher efficiency, but most GaN power ICs have significantly lower breakdown voltages than SiC. SST designers therefore spread the grid voltage across many smaller converter cells connected in series.

That arrangement creates a modular architecture, but it can also increase system cost and control complexity. Device performance therefore matters alongside the number of stages and the complexity of controlling them. GaN improves switching, while its voltage limit shapes the system around it.

What does Infineon's 900-V switch change?

Infineon will supply the first 900-V GaN-based bidirectional switches to Enphase for use in solid-state transformer power modules. The monolithic devices extend GaN's operating range from 650 to 900 V while retaining high-frequency switching.

Enphase will deploy the devices in its IQ Solid-State Transformer product for AI data centers. Each rack-shaped unit contains 342 modules, whose high switching frequency and control bandwidth support fast, precise load management.

A single rack accepts input voltages as high as 34.5-kV AC and can deliver up to 1.25 MW. Its DC output supports NVIDIA's 800-V DC architecture and the OCP ±400-V DC standard, linking the module to two rack-power formats.

Unlike a standard power switch, a GaN bidirectional switch integrates bidirectional voltage blocking and current conduction in a single device. Combining those functions in one device simplifies power stages and reduces component count while supporting the high-frequency operation needed for greater power density and smaller magnetic components.

The higher blocking voltage lets engineers reach higher system voltages with fewer converter stages. It therefore supports the shift toward 800-V DC distribution in AI centers, where removing conversion steps can simplify the power path. The device turns higher voltage into a system-level reduction in parts.

Can the same devices serve solar installations?

The 900-V technology could also apply to commercial solar inverters. It supports three-phase, line-to-line designs for 480-V applications in the United States, reducing switch count, power losses and bill-of-materials costs.

That route gives Infineon and Enphase a potential application beyond AI data centers. The same voltage gain can reduce parts in both data-center converters and 480-V solar inverters.

What remains unproven before deployment?

The announcement establishes successful 900-V device testing, product integration and a stated rack capacity of up to 1.25 MW. It does not specify shipment volumes, customer commitments, pricing or revenue, and the 1.25 MW figure describes capacity rather than announced production output.

Production qualification must still confirm that the devices work reliably at scale. If that step succeeds, the commercial test will be whether GaN's efficiency and component savings can offset the modular design's higher system cost and control complexity, particularly against SiC-based converters.