Manfred Harrer, who runs research and development for Hyundai Motor Group, was asked whether the industry should still be pouring money into solid-state batteries. His answer, reported by InsideEVs on 27 September 2026, was blunt: "You cannot give up right now on that. That's clear."
He put a timeline on it. Small-volume cars with solid-state cells should reach the market within five years. He also put a limit on it: raw material costs will stay extraordinarily high for many years as the technology scales, which keeps these batteries out of the mass market well beyond that first appearance.
Two numbers that have to be read together
Most solid-state coverage reports the first of those and skips the second. The pairing is the useful part.
| Claim | What Harrer said |
|---|---|
| First cars | small-volume models within five years |
| Mass market | not for many years after, on raw material cost |
| Why bother | smaller pack, better fast charging, longer range |
| Hyundai's position | developing in-house and with partners including Solid Power |
Harrer called solid-state "the big bet in the industry right now," which is accurate and also the reason to treat any single timeline carefully. A bet is not a schedule.
It fits a pattern we have been tracking
Hyundai is not making this claim into a vacuum. Over the past weeks the same technology has produced three different kinds of announcement:
- Mercedes-Benz secured first rights to ProLogium's Gen4 cells and is testing them
- Geely claimed 500 Wh/kg solid-state cells entering pilot deployment, with Volvo and Polestar queued behind it
- Hyundai now commits to a five-year horizon for low-volume cars and says the cost problem outlasts it
Three serious manufacturers, three timelines, no production vehicle. What distinguishes Harrer's version is that it is the least flattering. A supplier claiming an energy density is making a technical claim; an R&D chief conceding that his own technology will stay too expensive for ordinary cars is making a commercial one, and commercial admissions tend to be the more reliable signal.
What it means for a Tesla buyer in Europe
Tesla has no announced solid-state programme. Its battery strategy has run the other way: cheaper chemistry rather than denser chemistry, with LFP in standard-range cars and the 4680 as a manufacturing bet rather than an energy-density one.
Read alongside Harrer's cost warning, that looks less like a gap than a different reading of the same problem. If solid-state arrives first in small-volume, expensive cars and stays there for years, it will not decide what a European buyer pays for a Model 3 or Model Y in that window. Tesla's competitive exposure over the next five years is to cells like CATL's Shenxing generation — cheap chemistry that charges fast — rather than to a premium cell in a halo model.
The thing to watch is not the launch date. It is whether anyone attaches a price to a solid-state car, because that is the number Harrer is warning about and the only one that changes what is on a European forecourt.
A caution on sourcing: this is one executive's assessment, given to reporters and published by a single outlet. Hyundai has not issued a production commitment, a model, or a date, and the five-year figure is a projection rather than a plan of record.
Update: 2026-09-28
BYD has since put the most aggressive timeline in the industry against the five-year horizon above. Executive vice-president Stella Li told Carwow's Spanish outlet in mid-September 2026 that "next year, we have one model that will be the first one with that technology", and InsideEVs reported the claim again on 28 September 2026. The scale attached to it matters more than the date: FinDreams, BYD's battery arm, plans small-batch production of sulfide-based all-solid-state cells covering roughly 1,000 vehicles around 2027, with mass production targeted around 2030, and early use is expected in Yangwang and flagship Denza models. That is a fourth timeline for the same technology, and it does not contradict Harrer's warning so much as illustrate it: a first car in 2027 built in the hundreds, and affordable cells at the end of the decade. Sources: BYD Will Put Solid-State Batteries In An EV Next Year: Executive, BYD to put solid-state battery technology into a vehicle next year, executive confirms.