Noak has €5 million and a decade of someone else's research. The Belgian spin-off, formed out of imec and Hasselt University, closed a seed round on 30 October to turn perovskite-silicon tandem solar cells from a laboratory record into a manufacturable product. Its target is 30–35% conversion efficiency. Conventional silicon cells top out around 27–28%.
The gap sounds small. In solar, it decides whether a market grows on cost reductions or on land, glass, and installation labour. Higher efficiency means fewer panels, fewer mounts, and less cable for the same megawatt. The same roof and the same inverter produce more power. That is why every major manufacturer is chasing tandem.
The moat is a 3D-woven back-contact foil and five years of field data across three continents.
Europe has already invented a good part of this technology. The continent hosts the labs, the IP, and the test sites. It manufactures a small share of the panels it installs. Noak is an attempt to keep one more step of that chain onshore.
Five years of outdoor data, then the factory
The technical case rests on a dataset. imec and UHasselt say they have run perovskite-silicon tandems outdoors for five years at more than 10 sites across Asia, Europe, and North America. The cells saw intense sun, heavy rain, extreme heat, and sub-zero cold. Most tandem stability claims come from accelerated lab tests. Field data is harder to produce and harder to argue with.
Noak contributes a perovskite layer stack built from proprietary chemistries and deposition methods that are meant to scale. The company says the next phase will focus on long-term stability and performance at scale. Those are the two numbers that decide whether a bank finances a gigawatt line.
The wiring goes on the back
Standard solar cells collect current on the front. That metal grid shades part of the cell, and silver is expensive. Noak's 3D-woven back-contact foil moves the electrical connections to the rear. The company says this removes front-side metallisation, cuts shading losses, and reduces the use of rare and expensive metals.
The architecture also splits the tandem into smaller sub-cells wired in series and parallel. That gives module designers more freedom and trims metal use further. Noak is working with suppliers on certified recycled metals, and the design is meant to be disassembled at end of life. Those choices matter in a European market that treats raw-material dependence as a strategic risk.
TaiyangNews notes that Noak has not disclosed the foil's construction, its metallisation materials, or the interconnection process. The claims are specific enough to test, not specific enough to replicate.
The competition is not standing still
Oxford PV has shipped tandem modules at 26.9% efficiency. LONGi has reported 34.85% at cell level. Asian manufacturers have the factories, the supply chains, and the balance sheets to move a proven design into production faster than a €5M start-up can.
Noak's answer is partnerships. The seed money is earmarked for work at EnergyVille in Genk and for preparing gigawatt-scale manufacturing deals. That is a realistic plan for a small company. The first demonstration is the easy part. The ten-thousandth module is the hard part.
As we wrote in November, Flexell Space has booked two Falcon 9 launches to test perovskite cells in orbit, where the environment is harsh but the volume is tiny. Noak is chasing the opposite problem: a terrestrial product that has to survive decades on a roof and compete on cents per watt.
Solar installations reached about 3 terawatts in 2026. imec puts the 2050 requirement near 50 terawatts. The world will not get there on silicon alone. Noak's €5 million will not build that industry. It might show whether Europe can own a meaningful slice of it.