Most concept cars never reach a showroom. They exist to prove a direction the maker is willing to fund. The 3 kW bidirectional charger Fraunhofer IAF showed at PCIM Europe 2026 reads the same way.
The power number is almost a distraction. At 3 kW, this off-board, single-phase, 800 V DC charger is slower than the 11 kW and 22 kW on-board chargers already in cars. What makes it worth a second look is the device inside it: a 1200 V-class GaN module aimed at a part of the 800 V battery market that neither today’s GaN nor today’s SiC fits cleanly.
So the question this demo really poses is narrow and concrete: where does 1200 V GaN actually belong?
The awkward middle of 800 V charging
GaN4EmoBiL, the project behind the demo, started in 2023 with a problem most spec sheets hide. For an 800 V battery doing two-way charging, every device choice is a compromise:
• SiC works and is qualified, but it carries a cost premium.
• Silicon is cheap, but efficiency and power density run out early.
• 650 V GaN-on-Si is efficient and affordable, yet too low in voltage for an 800 V bus without cascoding or extra stages that eat the savings.
That leaves an opening between 650 V GaN and 1200 V SiC. The project’s stated goal is to fill it with a low-cost 1200 V device that covers an 800 V bus without those workarounds.
Getting GaN to hold 1200 volts
The harder part is physics. Lateral GaN-on-Si has been in production for years, but the conductive silicon underneath creates a vertical breakdown path that keeps most commercial parts at 650 V.
In 2024 Fraunhofer IAF laid out three routes past that ceiling:
1. GaN-on-Si HEMTs, pushed through material and device optimization to over 1200 V static blocking, with switching demonstrated above 1100 V.
2. GaN-on-insulator HEMTs, the centerpiece – replacing conductive silicon with sapphire, SiC, or GaN carriers to weaken the vertical breakdown path and lift the voltage further.
3. Vertical GaN, a longer-term bet the institute frames on a roughly ten-year horizon.
The insulating-substrate route matters most here, because 650 V parts leave too little voltage margin for an 800 V battery, while 1200 V starts to clear it.
Bidirectional is the harder half
Voltage is only one wall. A two-way charger has to pull energy from the grid and push it back to a home, a battery, or the grid, which means blocking and conducting in both directions, plus the control and protection that come with it.
This is where the monolithic bidirectional switch Fraunhofer IAF disclosed in 2025 fits. Built in GaN-on-insulator with integrated free-wheeling diodes, it blocks and conducts both ways in one device instead of two back-to-back transistors, which can cut chip area and conduction loss.
The contrast with the market is sharp. Commercial bidirectional GaN today still clusters at 650 V. Infineon’s CoolGaN BDS is the clearest example, aimed at solar microinverters and server power. Fraunhofer IAF is reaching straight for 1200 V and an 800 V battery. That is the most distinctive thing about the route, and also the reason it is still in the lab rather than on a shelf.
Why 3 kW, and why now
Seen as a charger, 3 kW looks underpowered. Seen as an interface, it looks deliberate. The demonstrator weighs 5.7 kg, fits in 8.3 liters, spans a 150-920 V battery range, and carries CCS plus Schuko connectors. It is built to sit in a garage or move with you, not to fast-charge.
The timing tracks the market it serves. University of Stuttgart’s part of the project targets a near-product 3.4 kW off-board cable now and an 11 kW three-phase on-board concept later, on a low-cost 1200 V GaN route using sapphire or QST substrates, with V2H and V2G reliability evaluated past 60,000 hours.
And the demand side is arriving. Volkswagen and Elli plan a vehicle-to-grid service for private customers in Germany from Q4 2026, with pre-registration opening in mid-2026. A compact, affordable two-way DC interface has a place in that world that a 22 kW charger does not.
What this does to the SiC line
Putting 1200 V GaN into an 800 V two-way charger invites the obvious framing: GaN coming for SiC. That read is premature.
In fast charging, traction inverters, and storage PCS, SiC keeps a mature module base, automotive qualification history, and customer trust. GaN’s path into those sockets runs through full system validation, well beyond datasheet parameters.
Where the line could actually move is narrower:
• Bidirectional topologies, where one 1200 V monolithic switch can replace two reverse-series SiC devices and save area, loss, and gate-drive complexity.
• System cost, where a single 1200 V GaN stage avoids the cascoding an 800 V bus forces onto 650 V parts.
• The 3-11 kW band, where compact, light, two-way DC interfaces reward GaN’s frequency and density.
The competition is drifting away from raw material comparisons toward a sharper question: in which power and topology window is the system simpler and cheaper?
The line the public record hasn’t drawn
Here is what keeps this from being a finished story. The demo runs a 1200 V GaN module. Fraunhofer IAF has separately built a 1200 V monolithic bidirectional switch. The intuitive move is to assume the second is inside the first.
The public materials do not confirm that. “1200 V” describes the device voltage class of the module; “bidirectional” describes what the system does. Whether the 2025 MBDS actually sits in this 3 kW box is a connection the disclosures stop short of making.
Everything else is still missing too: efficiency curves, thermal data, dynamic Ron, gate reliability, the full 60,000-hour result, BOM comparisons against SiC, a path to volume. The technical direction is legible. Whether 1200 V GaN can carry real energy through an 800 V interface, and whether the switch already exists to do it, is the part the next data release has to answer.
