The Panasonic EverVolt: fifty years of HJT, and the structural economics that ended them.
On 28 April 2025, Panasonic discontinued every EverVolt solar and storage product, ending a heterojunction programme that had run for fifty years under two company names. The technology held world records to the end. What killed it was the economics of building at boutique scale in a market that had gone commodity.
Panasonic inherited a technology it didn't invent, and a decade-long patent moat that came with it.
The heterojunction concept was developed at Sanyo Electric, not Panasonic. Sanyo entered solar research in 1975, commercialised amorphous silicon cells by 1980, and filed the foundational HIT patents through the 1990s; commercial mass production of HIT modules began in 1997 at a first module efficiency of 14.4%, competitive with the best standard crystalline products of the time and already carrying a measurably better temperature coefficient in warm climates. Sanyo's core HIT patents held competitors out of the heterojunction space for roughly a decade: no other manufacturer had meaningful commercial HJT volume until those patents began expiring around 2010 to 2011.
Panasonic acquired a controlling stake in Sanyo in 2009 and began trading solar panels under the Panasonic HIT brand from April 2012, with the technology, factories and engineering teams transferring intact. The records were real and peer-verified, not marketing claims: a temperature coefficient of −0.258%/°C, a back-contact HIT cell at 25.6% in 2014 (then a world record for non-concentrated crystalline silicon), and the world module-efficiency record of 23.8% in 2016, with a degradation profile that outperformed every major P-type architecture of the period. By 2017, Panasonic had shipped over 18 million HIT modules and produced more than 1 billion HIT cells cumulatively. The product earned DNV GL Top Performer status in 2018. For a manufacturer operating at approximately 1 GW annual capacity, that was a genuinely strong record.
The technology survived five decades; the manufacturing model did not
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Sanyo research beginsThe programme starts in amorphous silicon before the HIT architecture is commercialised.
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HIT enters productionCommercial mass production begins at 14.4% module efficiency.
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Panasonic takes overPanasonic acquires Sanyo and moves the technology under the Panasonic HIT brand.
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Patent moat expiresCompetitors gain access to an architecture previously protected from meaningful volume competition.
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Manufacturing endsPanasonic closes its own factories and moves the panel business to an OEM model.
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EverVolt discontinuedSolar and residential storage products exit while the parent continues other battery businesses.
When Sanyo's HIT patents expired in 2010, the protected advantage that had funded the business dissolved with them.
Chinese manufacturers entered once the moat lifted. By 2023, over 24 manufacturers were beginning or augmenting HJT capacity; by January 2025, Huasun alone had shipped 10 GW of HJT modules cumulatively. Mass-production HJT efficiencies from Chinese manufacturers reached 24.0% to 24.8%, not far behind Panasonic's laboratory records and at a fraction of the equivalent manufacturing cost. The technology Panasonic had developed over thirty years was being manufactured at Chinese commodity scale within fifteen years of patent expiry, and the efficiency premium that had been the primary commercial justification for Panasonic's pricing compressed toward zero.
Two failed pivotsTwo major strategic partnerships collapsed within twelve months, and both failures pointed the same direction.
Recognising the trajectory, Panasonic attempted two partnerships to alter its cost and distribution position. In 2016, Panasonic and Tesla announced a joint manufacturing arrangement at the former SolarCity facility in Buffalo, New York, to produce solar cells for Tesla's Solar Roof product. Panasonic began manufacturing at Buffalo in 2017; by 2020, Tesla had pivoted to sourcing solar cells from Chinese manufacturers, and Panasonic announced it would cease Buffalo solar production by May 2020, with a full exit by September. The arrangement had produced limited commercial volume.
Concurrently, Panasonic announced in May 2019 a collaboration with Fujian-based GS-Solar (China) Company Ltd, intending to transfer its Malaysian manufacturing subsidiary and establish joint R&D. GS-Solar failed to meet contractual requirements by the agreed deadline; an extension granted for COVID-19 disruption was also missed. In July 2020, Panasonic cancelled the arrangement and reserved the right to pursue legal remedies.
Two major strategic partnerships abandoned within twelve months. In February 2021, Panasonic announced it would exit panel manufacturing entirely, closing its Malaysian and Shimane factories by March 2022, and pivot to an OEM model selling third-party-manufactured panels under the Panasonic brand. A company spokesperson stated at the time: "Panasonic is of the opinion that cost competitiveness cannot be maintained."
The relaunch that didn't recover the shareEverVolt was a credible product. It did not stop the share collapse.
The EverVolt line launched in 2021 to 2022 as a re-engineered HJT range: larger half-cut cells, updated module architecture, compatibility with prevailing inverter standards. The flagship HK2 delivered approximately 22.2% module efficiency at 420 to 430W, with a 25-year TripleGuard warranty covering product, performance, parts and labour. On technical merit, it was a credible product.
The marketplace data did not reflect that credibility.
In the same period, Panasonic Group committed to a US$4 billion EV battery cell manufacturing facility in Kansas, targeting Tesla and other automotive customers. Inside a diversified conglomerate, capital allocation is a competitive process: a residential solar business contributing a small and declining share of group revenue, competing against Chinese manufacturers at a structural cost disadvantage, was not positioned to win that competition against a $4 billion EV battery anchor programme. The April 2025 exit followed.
Not an isolated caseLG exited in 2022. Kyocera pulled back regionally. Meyer Burger chose to fight, and filed for bankruptcy instead.
Panasonic's arc is the second iteration of the same story in three years. LG Electronics exited solar in February 2022, citing rising material and logistics costs, supply chain constraints and intensified price competition, with reporting attributing the underlying driver to Chinese rivalry; solar had represented approximately 1.5% of LG Electronics' total revenue across twelve years in the market, and LG honoured its warranties and exited in an orderly fashion. Kyocera followed a regional exit pattern, withdrawing from North and South American operations in 2016 and announcing the permanent closure of its German Solar Technical Service Center in March 2026.
Meyer Burger chose a different path. Rather than managing an exit, the Swiss manufacturer, which had previously supplied HJT manufacturing equipment to others, chose to become an HJT manufacturer itself, opening plants in Germany and Arizona. The business model required Chinese module pricing to remain non-competitive (it did not), US IRA Section 45X manufacturing credits to flow at scale (the plant never reached production volumes sufficient to generate them), and a master supply agreement with developer DESRI to hold (it was terminated in November 2024, eliminating an estimated 90% of projected 2025 to 2026 revenue). Meyer Burger filed for Chapter 11 bankruptcy in the US in June 2025, reporting liabilities estimated at $500 million to $1 billion; factory equipment was later sold to Indian manufacturer Waaree Solar Americas for $18.5 million.
The comparison is instructive. A managed exit by a solvent parent corporation, Panasonic's or LG's, is a materially better outcome for end customers than a financially distressed collapse by a standalone manufacturer.
What this means beyond PanasonicFive structural conditions produced this exit, and they apply to any residential solar manufacturer operating below roughly 5 GW.
Technical quality could not offset five structural pressures
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01
The patent moat expired
HJT became reproducible by competitors with much larger manufacturing economics.
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02
Boutique scale stayed expensive
A roughly 1 GW producer carried fixed costs against competitors operating at tens of gigawatts.
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Capital had better alternatives
Inside Panasonic, residential solar competed with larger EV battery investments for funding.
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Two partner pivots failed
Tesla removed the US production route and GS-Solar failed to deliver the proposed China pathway.
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05
Warranty outlived the product line
The legal promise remains, but replacement supply and claim handling become more complex after exit.
- Patent moats expire. The specific technology a boutique manufacturer uses as a pricing differentiator is, eventually, reproducible by competitors with better manufacturing economics. Sanyo's HIT moat held for roughly fifteen years post-commercialisation, not a long window relative to a 25-year product warranty.
- Boutique-scale unit economics are structurally challenged. Spreading R&D, quality assurance, warranty reserves and fixed manufacturing costs across 1 GW of annual output produces materially higher per-watt costs than spreading equivalent overheads across 50-plus GW. As efficiency gaps compress, the price premium needed to offset that disadvantage gets progressively harder to justify.
- Conglomerate capital allocation is a risk, not a safeguard. A large parent provides warranty backstop, which is real value for end customers, but the solar business also competes internally for capital against divisions with stronger return profiles. When EV batteries or semiconductors offer better returns than a declining-share solar line, the solar line loses that argument.
- Single-partner dependency concentrates risk. Both of Panasonic's failed pivots involved one strategic partner. Tesla's manufacturing pivot eliminated the Buffalo revenue channel outright; GS-Solar's contractual failure eliminated the Chinese cost-reduction path. A business whose strategic options depend on one counterparty inherits that counterparty's risk.
- The warranty horizon is a contingent liability, not just a marketing claim. For customers who chose a premium brand specifically for warranty confidence, the brand's exit is a material change in the character of that guarantee, even where the parent commits to honouring it. The warranty stays legally valid; the practical claims process and long-term ability to source replacement modules both get measurably more complex.
This was a managed exit, and it likely came several years later than it should have.
Panasonic's 2025 departure was managed competently given the circumstances: the company stated its position clearly, committed to warranties, established a support channel, and gave the installer channel reasonable notice. That puts it in a different category from an insolvent exit.
The more useful question is whether the exit happened at the right time. The margin trajectory was evident by 2018 to 2019: the HIT patent moat was gone, Chinese scale was beyond any realistic competitive response from a 1 GW producer, and two major strategic partnerships had already shown that no cost-reduction path existed on acceptable terms. A planned exit in 2019, with a three-year channel wind-down, fully-funded warranty reserves and replacement-product recommendations built into the transition, would have been a better outcome for the installer ecosystem than the EverVolt relaunch, the continued share erosion, and a 2025 closure from a position of structural weakness. Knowing when to exit well is a different skill from fighting to sustain a market position past the point where that fight is winnable.
What this means for the panels on this benchmarkreview.solar carries a sourced flag on this product. Here is the warranty position behind it.
The Panasonic EverVolt HK2 carries a red-severity flag on this benchmark: a category exit, not an insolvency, and its score is frozen at the point of exit rather than recomputed against current-generation competitors. Panasonic Group remains a major global manufacturer with ongoing EV battery operations and the financial capacity to honour outstanding obligations, and it has committed to honouring warranties for both installed and uninstalled EverVolt systems. No source located for this piece specifies a registration cutoff date attached to that commitment; one widely-cited figure elsewhere online, 31 December 2025, refers to a solar-warranty administrator's own product-listing window, not to a Panasonic-stated deadline, and is not repeated here.
The practical risk for existing owners is not warranty validity. It is replacement-module availability for defect claims over a 25-year horizon. HJT as an architecture is actively manufactured by multiple producers; any warranty replacement is likely to be sourced from an OEM manufacturer rather than a Panasonic-labelled module, worth factoring into expectations at claim time, though not unusual in a market where module manufacturing regularly changes hands. The HIT/HJT architecture itself remains technically sound. It did not exit the market because it failed. It exited because the business model that sustained it could not.
Full scored record for this product: review.solar/products/panasonic-evervolt-hk2.
Sources19 references
- PV Magazine USA: Panasonic exits solar and battery storage, ending decades-long journey (Apr 2025)
- EnergySage: Panasonic exits solar and energy storage market, marketplace share data (2025)
- PV Tech: Back-contact HIT solar cell from Panasonic pushes efficiency record to 25.6% (2014)
- Panasonic Newsroom: World-record 23.8% module efficiency (2016)
- Panasonic press release: IEEE Corporate Innovation Award citation (2012)
- GP Solar Panels: Sanyo solar panels, company history
- Wikipedia: Heterojunction solar cell
- pv magazine: Panasonic celebrates 20 years manufacturing PV module HIT (2017)
- PV Tech: Huasun reaches 10 GW in cumulative global HJT shipments (Jan 2025)
- Wikipedia: Gigafactory New York
- TechCrunch: Panasonic is ending its solar cell partnership with Tesla (2020)
- Panasonic Holdings: investor document on GS-Solar collaboration (Jul 2020)
- Panasonic press release: GS-Solar arrangement cancellation (Jul 2020)
- pv magazine: Panasonic to exit solar manufacturing (Feb 2021)
- Solar Info Ireland: Panasonic EverVolt HK2 specifications
- LG press release: LG to exit solar panel business (Feb 2022)
- Kyocera Germany: Solar Technical Service Center closure notice
- Reuters: Meyer Burger's largest customer DESRI terminates contract (Nov 2024)
- Electrek: Meyer Burger US solar factory closure, 282 workers laid off (Jun 2025)
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