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The Grid of the Future is Here: SMA Achieves First Certification for Grid-Forming Battery Inverters
In a landmark move for the energy transition, German inverter giant SMA has announced it is the first company to receive a unit certificate in Germany for its Sunny Central Storage battery inverter to operate in grid-forming mode with instantaneous reserve. This isn't just a technical milestone; it is the key that unlocks the full potential of renewable energy to not just feed the grid, but to actively stabilize and control it—a function traditionally reserved for large fossil fuel and nuclear power plants.
Alan Zhu
September 26, 2025
This certification paves the way for battery storage projects to participate in Germany's new instantaneous reserve market, set to launch in early 2026, creating a crucial new revenue stream and fundamentally changing the role of inverters in the energy system.
What is Grid-Forming with Instantaneous Reserve? A Primer
To understand why this is a big deal, we must distinguish between traditional and next-generation inverter technology:
Grid-Following Inverters (Traditional): Today's standard. They connect to the grid and inject power, but they require an existing, stable grid signal (voltage and frequency) to "follow" and synchronize with. They are essentially passive contributors. If the grid goes down, they shut off.
Grid-Forming Inverters (Next-Gen): These inverters can create a stable grid signal themselves. They behave like a traditional power plant's rotating generator, providing inertia and stability. They can "black start" a grid and are essential for a network with very high levels of renewables.
Instantaneous Reserve (Momentanreserve): This is the ability to respond within milliseconds to fluctuations in grid frequency (e.g., caused by a power plant tripping offline or a sudden loss of load). It's the "first responder" service that keeps the grid stable at 50 Hz. Historically, this was provided automatically by the kinetic energy stored in the spinning masses of large turbines in coal, gas, and nuclear plants.
SMA's certification proves their inverter can provide this critical service electronically, replacing the need for fossil-fueled spinning reserves.
The Significance of the Certification
This is more than a product launch; it's a regulatory and technical breakthrough.
Market Access: The certification is based on strict German standards (VDE-AR-N 4410-20 and VDE-AR-N 4130). It is the formal approval needed for projects using this inverter to bid into Germany's upcoming instantaneous reserve market, creating a new, high-value revenue stream for battery storage owners.
Technical Validation: It confirms the inverter meets exhaustive technical requirements for overvoltage behavior, settling times, and performance, proving the technology is no longer "immature." This lifts a major barrier to its widespread adoption.
Enabling the 100% Renewable Grid: As Germany shuts down its conventional power plants, it loses the inherent inertia that keeps the grid stable. Grid-forming inverters are the essential technology that fills this void, making a secure, 100% renewable grid technically feasible.
Comparative Analysis: The Evolution of Inverter Capabilities
The following table illustrates the paradigm shift this certification represents.
Feature | Traditional Grid-Following Inverter | SMA's Certified Grid-Forming Inverter | Impact of the Change |
|---|---|---|---|
Core Function | Follows an existing grid signal. | Forms and maintains a stable grid signal. | Enables renewable-dominated grids. |
Provides Inertia | No. Provides zero synthetic inertia. | Yes. Electronically mimics the inertia of spinning turbines. | Replaces retiring thermal power plants. |
Response to Grid Events | Reactive, can be slow. | Proactive, instantaneous (milliseconds). | Dramatically improves grid resilience and stability. |
Operation During Outages | Shuts off (anti-islanding). | Can potentially island and black-start. | Enhances local resilience and reliability. |
Revenue Streams | Energy arbitrage, frequency regulation. | + Instantaneous Reserve, Enhanced Grid Services | Improves battery project economics. |
Grid Requirement | Needs a strong, existing grid. | Can strengthen weak grids or operate independently. | Future-proofs grid infrastructure. |
The Energy Expert's Verdict
SMA's achievement is a watershed moment for the entire energy sector. It signals that the technology to build a resilient, post-fossil-fuel grid is not only available but is now officially certified and bankable.
Implications for the Market:
For Project Developers & Asset Owners: This opens up the instantaneous reserve market as a new, high-value application for large-scale battery storage. It significantly improves the business case for investing in BESS projects by diversifying and enhancing their revenue potential.
For Grid Operators: It provides a certified, scalable tool to manage grid stability as conventional power plants retire. It transforms batteries from simple energy assets into essential grid-stability assets.
For the Energy Transition: It removes a critical technical obstacle. The lack of grid-forming capabilities was a major theoretical limitation to achieving very high renewable penetration. This certification proves that limitation has been overcome.
Final Thought: SMA being first is a competitive win for them, but the real winner is the energy transition itself. This certification validates a technological path forward that is based on power electronics and software, not spinning steel. It marks the beginning of the end of the era where fossil fuels were deemed "necessary" for grid stability. The future grid will be formed and secured by inverters, and this announcement is a definitive step into that future.
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