SMA Clears Germany's Grid-Forming Bar for Inertia First

SMA Solar Technology has become the first inverter manufacturer to receive grid-forming certification for the German inertia market, making its battery inverter the first unit certified as capable of supplying inertia to Germany's grid.

Inertia used to be a by-product. For a century it came free with the way electricity was made: heavy turbine shafts spinning in step with the grid, storing kinetic energy that resisted any sudden change in frequency. Now Germany is buying it as a service — and SMA Solar Technology has become the first inverter manufacturer whose battery inverter is certified to sell it.

The certification, reported by Energy Storage News, covers grid-forming capability for the German inertia market. In plain terms, SMA's unit has been assessed and approved as able to do something inverters historically were not asked to do: set the grid's voltage and frequency reference itself, rather than measure what the grid is already doing and follow along.

Why Germany Started Paying for a Physical Property

Every coal, gas, nuclear and hydro plant that closes takes its rotating mass with it. Wind and solar arrive through power electronics, which by default are grid-following: they lock onto the frequency they detect and inject current in time with it. That works beautifully while enough synchronous machines are still turning. It works much less well when they are not, because a grid with little inertia changes frequency faster after a fault — and fast frequency change is what trips protection relays and cascades outages.

Germany has pushed further and faster into inverter-based generation than almost any large industrial grid, which is precisely why the inertia question landed there first as a procurement problem rather than a research paper. The answer regulators and system operators have converged on is to define inertia as a deliverable product, write technical requirements for it, and certify equipment against those requirements. A battery inverter that passes can be paid for behaving, electrically, like a flywheel.

What Grid-Forming Certification Actually Demands

Grid-forming is a harder engineering problem than it sounds, because the inverter has to commit to a voltage waveform before it knows what the grid will ask of it. A grid-following inverter can hedge; a grid-forming one cannot. Broadly, certification regimes of this type test whether a unit can:

• Maintain an internal voltage and frequency reference independent of the surrounding network
• Respond to a frequency disturbance within milliseconds, in the same direction and on the same timescale a spinning mass would
• Ride through faults without disconnecting, while continuing to support voltage
• Do all of the above repeatably, verifiably, and without damaging itself or the battery behind it

That last point is the commercial catch. Synthetic inertia is delivered in short, violent bursts of power. The inverter has to survive them and the battery has to tolerate them, which means the certification is really a statement about the whole power-conversion chain, not a firmware feature you switch on.

The Advantage of Being First on the List

First-mover certification in a regulated technical market is worth more than the headline suggests, for three reasons.

The first is procurement mechanics. Developers building battery storage in Germany who want to bid inertia revenue into their project models need equipment that is already approved. A certified inverter removes a financing risk — the risk that the revenue line disappears because the hardware never passes. Until rivals clear the same bar, SMA is the path of least resistance for anyone underwriting an inertia-earning asset.

The second is that certification is a moving reference point. The first product through a new conformity process tends to shape how the process is interpreted: which test sequences count, how edge cases are treated, what documentation satisfies the assessor. Competitors follow a trail that has already been walked.

The third is reputational, and it travels. Grid-forming requirements are being drafted or tightened in Britain, Australia, Ireland, Spain and across the United States as inverter-based resources displace thermal plant. A manufacturer that can point to a completed German certification arrives in those conversations with evidence rather than a datasheet claim. Germany's rules are widely treated as a demanding template.

Batteries Move From Energy Trading to Grid Services

The wider trend here matters more than one certificate. Grid-scale batteries were first justified on arbitrage — buy cheap, sell dear — and then on frequency response. Inertia is a step further along the same path: a service that used to be a physical inevitability becoming a contracted product with technical qualification attached.

For battery developers, that means an additional revenue stack on assets they are already building, without additional megawatt-hours. For grid operators, it means the retirement of synchronous generation stops being a stability cliff. For the supply chain — cells, cathode material, lithium, the inverters that sit between the battery and the wires — it means storage demand is being pulled by system reliability requirements rather than by energy prices alone, which is a steadier driver.

It also raises the technical floor. If inertia provision becomes normal in Germany, grid-forming capability stops being a premium differentiator and becomes table stakes, in the same way that fault ride-through did for wind turbines. Manufacturers who arrive late to that transition sell into a market where the capability is assumed and no longer commands a price.

What to Watch From Here

Three things will determine whether this certification is a milestone or a footnote.

How much inertia Germany actually procures, and on what contract terms, sets the size of the prize. A thin, occasional market rewards nobody. A deep, long-dated one changes how batteries are financed.

How quickly competing inverter makers follow determines how long SMA's exclusivity is worth anything. In power electronics, first-mover windows are usually measured in quarters rather than years, because the underlying control techniques are published and understood — the work is in qualifying them.

And whether other jurisdictions adopt comparable certification decides whether a German approval becomes an export credential or stays a domestic licence.

The Market Backdrop

The news landed on a mixed session in the United States. As of the last trade at 20:00 GMT on 29 September 2026, the S&P 500 tracker SPY was at $764.20, down 0.18% from a prior close of $765.61, with a day range of $762.35 to $766.98. The Nasdaq 100 proxy QQQ was at $737.93, up 0.19% against a $736.53 close. The Dow 30 fund DIA sat at $512.88, off 0.22% from $514.02. Nothing in that tape reflects a single European certification decision — but it is the environment in which storage equipment orders are being underwritten, and a market with no clear direction tends to favour projects whose revenue is contracted and technically qualified over those betting on price spreads.

That, ultimately, is what an inertia certificate buys: a revenue line a lender can understand.

Key facts

• Certification: First grid-forming certification for the German inertia market
• Company: SMA Solar Technology, inverter manufacturer
• Product: Battery inverter certified as capable of providing inertia to the German grid
• Market backdrop: S&P 500 proxy SPY $764.20, -0.18%, as of 20:00 GMT 29 Sep 2026

Frequently asked questions

What is grid inertia?

Inertia is the kinetic energy stored in the spinning mass of conventional power plant turbines. It resists sudden changes in grid frequency, giving operators time to react after a fault. As coal, gas and nuclear plants retire, that rotating mass disappears, and frequency moves faster after disturbances — which is why grids are now buying inertia as a service.

What does grid-forming mean for an inverter?

A grid-following inverter measures the frequency and voltage already present on the network and injects current in step with it. A grid-forming inverter establishes its own voltage and frequency reference instead, behaving more like a synchronous generator. That lets it support a grid with few spinning machines rather than depending on them.

Why does Germany need an inertia market?

Germany has moved further into wind and solar generation, which connects through power electronics rather than rotating turbines, than most large industrial grids. With less synchronous plant online, system stability depends on equipment that can replicate inertia electronically — so operators defined inertia as a procurable product with technical certification requirements attached.

What commercial advantage does SMA get from being first?

Developers financing German battery projects that plan to earn inertia revenue need already-approved hardware, which removes a financing risk. Being first also lets SMA influence how the certification process is interpreted, and provides evidence it can present in other jurisdictions drafting similar grid-forming rules, including Britain, Australia and the United States.

Is grid-forming capability hard to build?

It is harder than grid-following. The inverter must commit to a voltage waveform without knowing what the grid will demand, respond to frequency disturbances within milliseconds, ride through faults while supporting voltage, and survive repeated high-power bursts. Because those bursts stress the battery too, certification effectively tests the whole power-conversion chain.

How does this affect battery storage economics?

Inertia provision adds a revenue line to assets developers are already building, without extra energy capacity. That shifts storage demand toward being driven by system reliability requirements rather than only by electricity price spreads — generally a steadier driver, and one lenders find easier to underwrite than merchant arbitrage income.

Sources

• SMA battery inverter first to win grid-forming certification for German inertia market — Energy Storage News

Photo: qimono · Pixabay Content License — source