ADELAIDE, AUSTRALIA — August 21, 2026 — A battery that speaks AC directly. No separate inverter. No external power electronics cabinet. Just a battery that plugs into the grid like a machine.
That is the promise of the AC battery concept — and this week, Relectrify installed its first AC1 inverterless battery storage system in South Australia, moving the idea from prototype to deployed asset.
A conventional BESS is two boxes: a battery that stores DC power, and a separate inverter that converts DC to the AC the grid uses. The two are connected by cables, sized independently, and serviced separately.
An AC battery (also called a battery-integrated inverter system) embeds the inverter inside the battery module itself. Each module produces grid-compatible AC directly:
| Conventional BESS | AC Battery (Relectrify AC1) | |
|---|---|---|
| Inverter location | External, separate cabinet | Integrated into each module |
| Cabling | DC bus, heavy cables, protection gear | AC output, standard wiring |
| Scaling | Add battery + resize inverter | Add modules, each with own converter |
| Installation complexity | High (sizing, coordination) | Lower (modular AC building blocks) |
| Failure isolation | One inverter = single point of failure | Per-module, failures isolated |
The AC1 installation is one installation in one state. But it signals four shifts the broader market should track:
1. Inverter sizing problems disappear. Today's BESS projects spend months matching inverter capacity to battery capacity — and re-engineering when either changes. AC batteries scale module by module, each with its own rated converter, eliminating the matching problem entirely.
2. Efficiency gains at partial load. Large central inverters run inefficiently at low load. AC batteries can shut down individual modules and keep the rest operating near peak efficiency — meaningful for systems that spend most of their life below full power.
3. A new failure-isolation model. When a central inverter fails, the whole system stops. In an AC battery, one module's converter failing takes down only that module — a step-change in availability.
4. Standardization of the battery as a "grid appliance." AC batteries behave more like plug-and-play machines than engineered systems. That is the direction the whole industry is moving — and it will reshape how integrators, installers, and buyers think about BESS procurement.
For context, the AC battery is not new — the concept has been discussed for a decade — but it has never scaled. Reasons include:
- Cost: embedding power electronics in every module adds per-module cost that central inverters amortize better at utility scale
- Efficiency at full load: a large dedicated inverter is more efficient than many small integrated converters running at full output
- Established supply chain: the industry's entire inverter ecosystem, standards, and installer training assume external inverters
This is why the AC battery's first real deployments are appearing in distributed and C&I applications — where modularity, installation speed, and partial-load efficiency matter more than the last half-percent of full-load efficiency — rather than in gigawatt-hour utility projects.
For C&I and residential buyers, the AC battery trend reinforces two procurement principles that are already central:
- Modularity is the direction of travel. Whether inverter is integrated (AC battery) or external (conventional), systems that scale module-by-module and isolate failures are the future.
- Integration compatibility is a buying criterion. As power electronics migrate and modularize, documented inverter compatibility — like EXLIPORC's field-tested Victron integration — becomes a core specification, not a footnote.
EXLIPORC's 16kWh modular platform — field-tested with Victron, Fronius, SMA, Growatt, and Deye ecosystems — was built on the same principle driving the AC battery: the battery should be a clean, standard, plug-and-play building block that works with whichever power electronics architecture the project demands, today's or tomorrow's.
Sources: Relectrify AC1 first installation via Energy-Storage.News (August 17, 2026)
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