What happens after you build a better cell?
In the first OUTFOX webinar, the focus was on scaling solid oxide electrolysis cells to 900 cm² — the materials science, the manufacturing challenges, and why cell size matters for system economics. That session answered an important question: can the cells be made larger?
The second webinar asked the harder follow-on question: what does it actually take to turn those cells into working systems capable of producing hydrogen at industrial scale?
The answer, it turns out, involves a lot more than stacking cells into a box.
The Session
On 13 March 2026, OUTFOX hosted its second public webinar: Powering Up: System Designs to Multiply SOEL Stack Capacity. Three speakers — each approaching the problem from a different angle — shared what they have learned from working at the hardware end of SOEL development.
Jan Gustav Grolig, Chief Technology Officer at Elcogen, spoke about the stack development work carried out within OUTFOX — specifically, how Elcogen scaled its fuel electrode-supported cells from 144 cm² to 361 cm² and what that process revealed about the real constraints on cell scaling.
Tuomas Hakala, co-founder and CTO of Convion, presented the system integration perspective — why efficiency alone does not determine commercial success, how heat integration changes the economics of SOEL, and what a modular architecture from hot box to megawatt-scale unit actually looks like.
Andreas Mai, Technology Manager for SOEC and Power-to-X at Topsoe, shared results from Topsoe’s SOEC development programme — including 11,000 hours of operational experience with their core demonstrator and the thinking behind their 500 MW/year stack manufacturing facility in Herning, Denmark.
What the Speakers Covered
Scaling cells: the yield problem
Jan Gustav Grolig opened by framing the question that underlies the whole session: why does cell and stack size matter at all? The answer is straightforward — the more output you can get from a single stack, the simpler and cheaper the surrounding system becomes. Larger cells mean fewer manufacturing steps per megawatt, lower costs per kilogram of hydrogen, and a cleaner path toward 100+ MW installations.
But scaling is not straightforward. The biggest constraint, Jan explained, is not materials — it is yield. When you make cells larger, they become more susceptible to cracking during processing and sintering. Getting a high proportion of healthy cells out of a production line, consistently, is where most of the manufacturing work lies.
Within OUTFOX, Elcogen has adapted its production process and recipes specifically to address this — adjusting how the support layer is processed, how cells are handled and cut, and how printing parameters are tuned to maintain uniformity across larger surfaces.
Jan also introduced a principle that shaped much of the session: design for manufacturing. The decisions made early in a product development cycle — about tolerances, component interfaces, power electronics, and safety architecture — have an outsized effect on eventual production cost. Getting customers and component suppliers involved early, before design choices are locked in, is not a nice-to-have. It is what determines whether a product ever becomes manufacturable at scale.
System design: why efficiency is only part of the story
Tuomas Hakala brought the system integrator’s perspective — and with it, a useful corrective to discussions that focus too narrowly on cell or stack performance.
Efficiency matters, he argued, but its impact is asymmetric. At high electricity prices, SOEL’s efficiency advantage over low-temperature technologies like PEM or alkaline electrolysis becomes very large. At low electricity prices, the difference narrows. This means that the value of SOEL is most pronounced precisely in the industrial settings where electricity is more expensive — which is also where waste heat is often available.
Heat integration is central to Convion’s approach. When an industrial process provides steam or waste heat, the electrical energy required to produce a kilogram of hydrogen can be reduced by around 30% compared to a system relying on electricity alone. This is not a marginal improvement — it is a fundamental shift in the cost structure of the plant.
Hakala also discussed the 250 kW piloting platform that Convion is using for the OUTFOX system demonstration at VTT’s test site. This platform is specifically designed to allow gradual increases in current density during testing — giving the project the flexibility to push operating conditions and observe where limits actually lie, rather than operating conservatively within known boundaries.
Looking further ahead, Convion is developing a modular architecture centred on a megawatt-scale hot core module, with multiple modules grouped together to form a configurable 45 MW SOEC unit. The goal is a factory-manufactured, standardised system that can be delivered and installed without bespoke engineering on site — the same principle that has made solar and battery storage scalable.
Operational experience: 11,000 hours and dynamic operation
Andreas Mai presented Topsoe’s perspective.
Topsoe has been operating a SOEC core demonstrator at its facility in Denmark, configured to mimic a small green hydrogen unit with 350 kW electrical input. By the time of the webinar, the system had accumulated 11,000 hours of operation — including extended periods of steady-state electrolysis and deliberate dynamic testing.
One result stood out: Topsoe demonstrated that the system can switch from 100% to 0% load and back to 80% load in three minutes each way. This directly addresses one of the most persistent assumptions about solid oxide technology — that it is too thermally sluggish for renewable energy applications where power input varies. The limiting factor in these transitions is not the stack itself, but the balance-of-plant components: heaters, flow controls, and other auxiliaries that cannot respond as quickly as the electrochemistry allows.
On manufacturing, Andreas walked through what a 100 MW plant actually requires in terms of components — from millions of individual electrode layers, through hundreds of thousands of cells, to around 2,000 stacks. Each scale requires a different production philosophy: mass manufacturing at the electrode and cell level, series manufacturing for stacks, and series assembly for modules and cores.
Why This Matters
The OUTFOX project was designed around a specific insight: that solid oxide electrolysis cannot reach industrial deployment without addressing scale at every level simultaneously: cells, stacks, systems, and manufacturing.
The second webinar made that interconnection visible.
Watch the Recording
The full recording of Webinar 2 is now available.
▶ Watch: Powering Up — System Designs to Multiply SOEL Stack Capacity
The third and final webinar — Going Mainstream: Making SOEL a Major Player in Hydrogen Production — is also now available.
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