SST's Qualification Race Begins: First National Certificate, GW-Scale Orders and Carrier Pilots Land in One Week

Between 20 and 24 October, the solid-state transformer (SST) segment delivered four rule-changing events in five days: China's CAICT/Tairer lab issued the country's first SST product test report and certificate; China Mobile's CMCC Energy opened bidding on its SST-AIDC 800V DC supply prototype, with Goldpark first; data-center operator Vantage signed the world's first gigawatt-scale SST supply agreement with Heron Power; and TBEA launched its Roy Sync SST series in Tianjin with mass production announced the same day. All four point to one judgement: the SST competition has shifted from 'can you build it' to 'can you win the bid'. This article breaks down each event and translates the 49-item certification checklist into a spec sheet the high-frequency transformer engineer already knows.

1. Four events in seven days: the tickets arrive in one week

On 20 October, Hefei Sungrow (Yuanzhi) EnerNeo received the first SST product test report and certificate in China, issued by CAICT's Tairer System Lab together with Tairer Certification. The weight of this certificate lies in its '49 tests on the full unit' - covering system electrical performance, system functions, protection functions, insulation safety and operation reliability, down to system efficiency, dynamic voltage transients, overload capability, fault bypass, DCDC backup management and output short-circuit protection; type testing and initial factory inspection were completed together. Combined with the UL/IEC/EN/2 PfG system-level and component-level certification TÜV Rheinland granted during OCP (the core HF isolation transformer passing the 13.8kV reinforced-insulation special item), Sungrow became the only domestic SST vendor holding both 'China's first certificate' and 'EU/US dual-standard system-level certification'.

On the same day, CMCC Energy's 'SST-based AIDC 800V DC high-efficiency supply prototype' procurement completed its bid evaluation: Goldpark ranked first in package 1 with a proposed 100% share, Sungrow second, with the publicity period running to 26 October. The project is a 10kV-input, 800V-DC-output prototype and the first SST + 800V HVDC prototype validation inside China's operator system. For Goldpark this fills a key gap in its two-route map - an overseas 13.8kV line plus a domestic 10kV/800V line. Its 2025 10kV/2.4MW SST prototype for 800V HVDC had self-designed power units and HF isolation transformers, used SiC devices and modular integration, and cut footprint by over 60% versus conventional schemes; the company's Q3 new data-center orders reached 5.678 billion yuan, up 472% year-on-year.

On 21 October, data-center operator Vantage and Heron Power announced they had locked in more than 1GW of Heron Link SST capacity. Heron Link is a 5MW modular converter built on wide-bandgap semiconductors that converts medium-voltage grid power directly to 800VDC and integrates storage, with a target efficiency above 98.5% (a target, not a measured value). Heron was founded in 2024 by former Tesla executive Drew Baglino; its Morgan Hill, California plant is planned at 10,000 units/year, about 40GW, with mass production by end-2027 and total funding of 183 million USD; it had already signed a letter of intent with Crusoe for the Stargate Texas site. For context: before this, publicly traceable SST orders were all in the hundreds of MW - Delta around 500MW cumulative, Sungrow about 130MW framework. One GW is a step change in magnitude.

On 24 October, TBEA launched its Roy Sync SST series in Tianjin and simultaneously announced mass production at its Tianjin manufacturing base; the outdoor unit is already live at a Sichuan heavy-truck megawatt-charger pilot. On the same day, a committee of 96 academicians and experts certified 29 of TBEA's power-equipment products in one pass, 18 of them at internationally leading level.

2. From a 'prototype race' to a 'qualification race': three signals

Reading the four events together carries more information than any single order. Three signals stand out.

Certification is the ticket. For a year the industry compared who showed a prototype first and whose numbers looked better; but what actually blocks the bidder is compliance. SST long had 'no standard to follow, no certificate to test against', which is why Tairer's first certificate is repeated - it gives the AIDC bidding table a citable third-party credential. Note the shift in test focus: dynamic voltage transients, fault bypass and output short-circuit protection are now on the list, meaning the assessment is moving from 'how high is the efficiency' to 'can it survive a fault'. SST is being examined as a grid-connected device, not just a power supply.

The procurement unit jumped from 'units' to 'GW'. This change of unit is the key turn in the commercial story. When it moves from 'placing an order' to 'reserving capacity', what gets locked is not one device but the delivery window for years ahead - directly tied to the 24-48 month lead times of large Western transformers. Whoever puts capacity on the table first takes the hyperscaler's roadmap first.

Carriers entered the field, extending the scene from cloud to state-owned. Until now SST demand was driven almost entirely by cloud vendors and overseas CSPs, with operators mostly observers. China Mobile is among the largest AIDC players in China; once the prototype passes, it can be replicated across Suzhou, Zhejiang and Guangdong AI parks. The demand base is being made real: GCC 2026 has issued first-batch AIDC certifications to 14 data centers operated by 7 entities, totaling 1.4498GW; GTC Berlin's DSX Pod, with 800VDC plus liquid cooling and factory prefabrication, compresses 'arrival-to-token' from 4-5 months to about 1 month.

3. Inside the 49-item checklist: the HF transformer spec sheet

The certification list looks like it is for the system integrator, but item by item the weight lands on the magnetics. Three examples (Figure 2):

Insulation safety -> medium-voltage reinforced insulation and creepage. The primary-secondary withstand of the internal HF isolation transformer is no longer the design margin of a conventional power-frequency transformer; 13.8kV reinforced insulation has been split out by TÜV as a special certification item - meaning inter-turn, inter-layer and winding-to-ground insulation must be rebuilt to grid-equipment standards, not power-supply standards.

Dynamic voltage transients -> tolerance band of leakage and magnetising inductance. Large AI training load steps create voltage sags and surges on the DC bus, and the isolation transformer must hold magnetic balance through the transient. That requires leakage and magnetising inductance controlled to a tolerance band, not 'close enough'.

Output short-circuit protection -> short-circuit impedance and surge margin. On a short circuit, the transformer must limit fault current within milliseconds and coordinate with protection. The short-circuit impedance value directly sets the current-limiting ability and thermal-surge withstand - the hardest line in the design trade-off.

What deserves more attention is the signal of 'component-by-component audit'. TÜV already audits the HF isolation transformer separately; Tairer's 49 items cover the whole unit - the safety evaluation system is moving from 'whole-unit bundle' to 'point-by-point component audit'. For magnetics suppliers, this means the component once hidden in the integrator's BOM and backed by the integrator must now enter the bid with its own component-level certificate. Component-level certification is becoming the magnetics maker's direct ticket.

4. What a GW-scale order really means: from units to GW

Back to the magnitude itself (Figure 3). Delta's ~500MW cumulative and Sungrow's ~130MW framework were the public ceiling before; Vantage's single deal crosses 1GW. At 5MW per Heron Link unit, 1GW is about 200 units - not 'buy a few more', but scheduling delivery by production line rather than by device.

The magnitude leap carries two implications. First, medium-voltage direct-to-800VDC with integrated storage has been adopted by hyperscalers as a standard architecture, not a pilot. Second, reserving capacity replaces placing orders as the way to lock delivery timing. With Western large-transformer lead times already at 24-48 months (over 36 months above 100MVA/230kV), locking a production line two years ahead is the operator's rational hedge against lead-time risk. For domestic magnetics makers the signal is just as clear: when integrators start 'reserving capacity', upstream magnetics must shift from build-to-order to capacity-reserved supply.

5. Carrier pilots and launch-day mass production: two engineering paths

The two seemingly parallel events this week - CMCC's prototype bid and TBEA's launch-day mass production - actually represent two SST engineering paths, with different implications for magnetics suppliers.

One is the 'operator-led prototype-validation path'. Goldpark's CMCC win is contract-manufacturing in nature, closer to a 'sample-bench' qualifier: the industry consensus is still 2026-2027 for prototypes and demonstrations, with scale only after 2028. On this path, magnetics must first prove they 'run stably inside the prototype system', emphasising joint validation with the integrator.

The other is the 'manufacturer-led mass-production path'. TBEA announced launch and mass production on the same day, with the outdoor unit already live at a heavy-truck charger - evidence that the 800V DC supply chain is moving from component sampling to system-level engineering delivery. On this path, magnetics are tested on manufacturability and consistency - can you produce qualified HF isolation transformers stably on a line, not build one beautiful prototype. The two paths in parallel map exactly to the magnetics maker's two capabilities: prototype co-design and scaled delivery.

6. Four audit points for magnetics makers

Following the breakdown above, a magnetics maker - especially suppliers of HF isolation transformers, HF inductors and magnetic-integration devices - can translate this week's four headlines into a self-check list. Miss the last one and you may be out:

• Insulation audit. Do you have 13.8kV-class reinforced-insulation design and process capability? Are inter-turn, inter-layer and winding-to-ground test methods aligned to grid-equipment standards, not power-supply standards?
• Transient audit. Is the tolerance band of leakage and magnetising inductance quantitatively controlled? Facing AI load steps and bus-voltage sags, can the isolation transformer hold magnetic balance and clamp surges within limits?
• Short-circuit audit. Is the short-circuit impedance value back-derived from system-level short-circuit conditions? Are thermal-surge withstand and current-limiting margin sufficient to coordinate with protection?
• Manufacturability audit. When integrators reserve capacity, magnetics move from 'build one prototype' to 'stably produce ten thousand units'. Winding automation, process consistency and batch yield are the core of this gate.

A magnetics maker with engineering samples but no component-level certificate, or with a certificate but no capacity rhythm, now has an exposed weakness after this week. The SST qualification race is essentially testing these four items.

Conclusion

This week's SST shift looks like four news items but is, underneath, a rule change: from a 'prototype race' to a 'qualification race'. For integrators, Tairer's first certificate and a GW-scale order are milestones; for magnetics makers, the real watershed comes earlier - whoever first translates the certification checklist into magnetics specs and aligns capacity rhythm with the integrator's line-reservation plan captures this round of orders.

Among these four audit points, which one is tightest for the SST HF isolation transformer you are evaluating or sampling?