TL;DR
- The solid-state transformer (SST) replaces the iron-and-oil core with high-frequency power electronics — routing power bidirectionally, regulating voltage in milliseconds, and converting 10 kV AC to 800 V DC in a single stage.
- In one week of August 2026, Weiguang Energy closed a heavily oversubscribed Series B for SST scale-up and Zhiguang Electric energized Guangdong’s first fully proprietary SST demonstration base. Weeks earlier, Sungrow launched its EnerNeo SST with 130 MW of framework orders and immediate deliveries.
- Field data presented at SST China 2026: at the same 2.4 MW rating, an SST uses over 50% less copper, saves about 560,000 kWh per year, and occupies less than half the floor space.
- SSTs will not displace the conventional transformer fleet for years — but every insulation and component supplier should understand where the architecture is heading.
A century ago, two electrical titans fought a war over a single question: should the world’s power be delivered as direct current or alternating current? AC won, and its victory became the architecture we still live inside. From generator to socket, power flows through a chain of iron-core transformers that step voltage up for transmission and down for use — machines that would look familiar to the engineers who built them in 1920.
That hundred-year-old design finally has a challenger. The solid-state transformer, or SST, replaces the iron-and-oil core with power electronics — semiconductors switching at high frequency to change voltage directly. It does everything a conventional transformer does, plus things a transformer never could: it routes power in both directions, regulates voltage in milliseconds, and connects AC and DC worlds without extra conversion stages. As Tsinghua University professor Li Yongdong put it at the SST China 2026 conference: “A traditional transformer is a lump of iron that only transforms voltage. An SST is not even in the same category — it is an energy router.”
The Week the SST Went Commercial
In 2026, the SST crossed from laboratory to commercial projects at unusual speed. Consider what happened in China in a single week of August:
- August 4 — Weiguang Energy, a Xi’an-based SST pure-play founded by a Xi’an Jiaotong University power-electronics team, announced a Series B round of several hundred million yuan. More than 160 investment institutions competed for allocation; only about a dozen got in. The funds go primarily to SST product iteration and scale-up.
- August 7 — Zhiguang Electric energized its Coota SST demonstration base in Guangzhou’s Huangpu district, Guangdong’s first fully proprietary SST project. The installation hangs a 4.2 MW SST directly on the 10 kV AC grid and runs a public 800 V DC bus feeding a “PV + storage + ultra-fast charging” scenario. Seven companies signed intent-to-purchase agreements at the ceremony.
And a few weeks earlier, on July 9, Sungrow launched its EnerNeo SST — “available at launch,” with framework purchase agreements for over 130 MW signed the same day with East Sunshine and Zhonglian Data. By early September the company had already delivered its first units to customers, including two 2.5 MW EnerNeo SSTs for a major Chinese computing center, with energization expected within weeks. The EnerNeo converts 10–13.8 kV AC directly to 800 V DC at a rated 98.5% system efficiency and 312 kW/m² power density. Industry observers now describe 2026 as the SST’s first year of commercialization.
Why DC Is Coming Back
The driving force behind the SST is not nostalgia for Edison. It is efficiency — measured in the harshest currency the industry knows: electricity bills.
AI data centers expose the problem clearly. A server hall needs power delivered as DC, but the grid speaks AC. Getting from a 10 kV AC feeder down to 380 V AC at rack level, then converting to DC for the servers, can take nine or more transformation and conversion stages — and every stage wastes energy. Xu Chongfu, deputy chief engineer at XD Power Electronics, cited national project data at the conference: the average PUE of Chinese data centers reached 1.46 in 2024, with nearly 40% of losses occurring in multi-stage transformation and cooling. Electricity already accounts for 50–80% of a compute campus’s operating cost — and over 80% in high-density AI facilities.
The SST collapses this chain: one unit takes 10 kV AC in and delivers 800 V DC out. Huang Lang, chief engineer at Weiguang Energy, presented field measurements comparing an SST against a conventional transformer at the same 2.4 MW rating:
- More than 50% less copper
- About 560,000 kWh saved per unit per year
- Less than half the floor space
Renewables push in the same direction. Solar and storage produce DC natively; connecting them to an AC grid requires inverters at every node, with conversion losses and limited bidirectional capability. An SST-based architecture removes whole layers of conversion — which is why the technology is increasingly described not as a better transformer but as an energy router for a mixed AC/DC world.
Three Markets, One Technology
The commercial pull is coming from three directions at once.
AI data centers. Rack power density has jumped from single-digit kilowatts in legacy CPU halls to 250 kW-class GPU racks, with NVIDIA’s 2027 platforms targeting 1 MW per rack. Dense racks make every percent of conversion loss expensive, which is why NVIDIA, Google, and Microsoft are driving 800 VDC distribution standards through the Open Compute Project — with an LVDC solid-state transformer specification already at v0.3 and more than 80 equipment and infrastructure companies participating. We covered the demand side of this buildout in our analysis of the global transformer shortage.
Solar, storage, and charging. EV fast-charging, battery storage, and distributed solar all live on the DC side of the meter. An SST-based station connects them directly to medium-voltage feeders, eliminates separate conversion stages, and — critically — supports bidirectional flow. That turns charging stations and storage into grid-flexibility resources that can absorb or return power in milliseconds. Zhiguang’s Huangpu demonstration is built around exactly this “PV-storage-charging” flexible DC scheme, supporting V2G vehicle-grid interaction.
Renewable interconnection. Wind and solar farms feed variable power into networks that need voltage stability. An SST’s millisecond-level regulation smooths the interface, improving power quality and supporting higher renewable penetration without expensive grid reinforcement.
What the SST Does — and Doesn’t — Change
For all the excitement, the SST is not an overnight replacement for the transformer fleet. The installed base of conventional transformers is enormous, their cost and reliability are proven over decades, and high-voltage power electronics remain expensive and young in the field. Securities Times reporting noted that nationwide SST pilot installations still number only in the dozens, and conference participants were clear that meaningful deployment will take years. Traditional suppliers face no immediate displacement.
What is changing is the direction of travel. Power electronics are becoming a larger part of electrical infrastructure, and every serious supplier — in transformers and in insulation — needs to understand where the architecture is heading.
For companies that supply the transformer industry itself, the shift carries a quieter signal. The SST’s gains come partly from cutting material: less copper, smaller footprint, and a very different thermal and electrical environment. Conventional oil-paper insulation remains the standard for the vast majority of the fleet and will for decades — and as we covered in our analysis of China’s first fully domestic aramid-paper 110 kV transformer, that conventional fleet is itself still advancing. But the frontier is moving toward higher frequencies, faster voltage edges, and DC bias — stresses that demand insulation systems engineered for power electronics, from high-temperature aramid-based flexible laminates to corona-resistant films. Suppliers who can serve both the legacy fleet and the emerging DC world are positioning themselves for the long arc of the industry.
Frequently Asked Questions
Q: What is a solid-state transformer (SST)?
An SST replaces the conventional iron core and windings with high-frequency power semiconductor stages that convert voltage electronically. It performs the same voltage-stepping function as a conventional transformer while adding bidirectional power flow, millisecond voltage regulation, and native AC/DC conversion.
Q: Are solid-state transformers commercially available now?
Yes, at pilot and early-commercial scale. In 2026, Sungrow’s EnerNeo SST launched with 130 MW of framework orders and began deliveries to computing-center customers; Zhiguang Electric energized a 4.2 MW SST demonstration base in Guangzhou; and SST specialist Weiguang Energy closed a heavily oversubscribed Series B. Industry participants still expect broad deployment to take years.
Q: Why is 800 V DC such a big deal for AI data centers?
Higher voltage means lower current for the same power, cutting resistive losses and copper use. NVIDIA’s 800 VDC architecture — developed with Google and Microsoft through the Open Compute Project — targets 1 MW racks from 2027. An SST converts 10 kV AC grid power directly to 800 V DC in one stage instead of the conventional chain of nine or more transformations.
Q: Will SSTs replace conventional transformers?
Not in the foreseeable future. Conventional transformers dominate on cost, proven reliability, and installed base. SSTs will grow first where their unique capabilities — DC output, bidirectional flow, compact footprint — carry the most value: AI data centers, ultra-fast charging, and renewable-plus-storage nodes.
Summary: Betting With the Current
The new contest between AC and DC is not a rerun of the 1880s — it is an efficiency argument, and the numbers are one-sided. SSTs cut copper use by more than half, save roughly 560,000 kWh per unit per year, and collapse nine conversion stages into one. The three pillars of the modern grid — AI compute, renewables, and electrified transport — all reward that efficiency.
The transformers inside today’s substations will keep working for another generation. The ones ordered after 2030 may look very different. At SIDA, we supply the insulation materials both worlds depend on — from conventional pressboard and flexible laminates to the high-temperature aramid systems that power-electronics-era designs demand. Questions about material selection for next-generation designs? Talk to our engineering team:
📞 +86-15958243831 | 📧 jessie.feng@sidanm.com | 💬 WhatsApp: +86-15958243831 | 🌐 sidanm.com/contact-us
References
- CLS (财联社) — 直流重新走向主流 固态变压器或改变百年交流独大电力格局｜SST产业化元年 (August 2026)
- Securities Times — 智光电气：固态变压器Coota广州黄埔示范基地正式投运 (August 2026)
- Jiemian — 160家机构抢一位博士：为光能源B轮融资数亿元 (August 2026)
- China Securities Journal (中证金牛座) — 阳光电源：公司已向客户交付固态变压器，预计四季度投运 (September 2026)
- NVIDIA Developer Blog — NVIDIA 800 VDC Architecture Will Power the Next Generation of AI Factories
- SIDA — The Global Transformer Shortage: How Chinese Manufacturing Is Closing the Gap (September 2026)
