Fraunhofer ISE completes testing on grid-forming inverters, to publish results next month

Facebook
Twitter
LinkedIn
Reddit
Email
Grid-forming inverter testing at Fraunhofer ISE.
Fraunhofer ISE tested grid-forming inverters, covering a range of sizes, from seven companies. Image: Fraunhofer ISE.

The Fraunhofer Institute for Solar Energy System (Fraunhofer ISE) has completed testing work of grid-forming inverters currently available in the energy industry, and plans to publish the study’s results at the Wind & Solar Integration Workshop next month in Berlin.

The German testing house noted that “customer systems must also contribute to stabilising the power grid” of the future, as conventional grid systems are unlikely to be able to accommodate the volume of new renewable energy capacity planned in many countries. For example, the EU estimates that Europe’s grid systems would require over €1 trillion (US$1.2 trillion) in new investment for distribution and transmission grid developments in the next 15 years.

This article requires Premium SubscriptionBasic (FREE) Subscription

Try Premium for just $1

  • Full premium access for the first month at only $1
  • Converts to an annual rate after 30 days unless cancelled
  • Cancel anytime during the trial period

Premium Benefits

  • Expert industry analysis and interviews
  • Digital access to PV Tech Power journal
  • Exclusive event discounts

Or get the full Premium subscription right away

Or continue reading this article for free

In the solar industry, these “customer systems” would take the form of residential and community solar projects, potentially co-located with battery energy storage systems (BESS).

Whereas California has seen a more adversarial relationship between residential solar and storage operation and traditional grid operators emerge – this week the California Solar & Storage Association (CALSSA) called for utilities to be fined for approving residential projects in the state too slowly – Fraunhofer has worked in collaboration with German transmission system operators (TSOs) to build test criteria by which residential inverters could be assessed.

Fraunhofer and the four TSOs – 50Hertz Transmission, Transnet BW, Amprion and Tennet – assessed inverters supplied by seven companies, with a power range of up to 5MW and including pilot technologies and those in “series production”, against these criteria.

While the testing house did not provide further details on the assessment process, and said that it would provide the full anonymised results at the Berlin event from 7-10 October, it noted that a “willingness and commitment” of original equipment manufacturers (OEMs) to produce grid-forming products is essential.

“The devices exhibited similar behaviour under clearly defined requirements,” said Roland Singer, Fraunhofer ISE project manager of the ‘GFM Benchmark’ test. “In other cases, however, there were major differences, and we were able to provide the manufacturers with suggestions for optimisation for almost every device.”

Earlier this year, Sandy Klengel, group leader at the Fraunhofer IMWS, wrote a piece for PV Tech Power on the importance of effective testing methods for inverters, considering their role in the future of the world’s energy mix, and this week’s Fraunhofer announcement builds on that idea.

Both this article, and the Fraunhofer announcement, come as interest in European solar, and global small-scale solar, is growing; figures from Bloomberg New Energy Finance (BloombergNEF) show that investments into the European solar sector grew by US$30 billion between the second half of 2024 and the first half of 2025, as investors grow cautious about supporting utility-scale projects, and those in the US.

2 December 2025
Málaga, Spain
Understanding PV module supply to the European market in 2026. PV ModuleTech Europe 2025 is a two-day conference that tackles these challenges directly, with an agenda that addresses all aspects of module supplier selection; product availability, technology offerings, traceability of supply-chain, factory auditing, module testing and reliability, and company bankability.
10 March 2026
Frankfurt, Germany
The conference will gather the key stakeholders from PV manufacturing, equipment/materials, policy-making and strategy, capital equipment investment and all interested downstream channels and third-party entities. The goal is simple: to map out PV manufacturing out to 2030 and beyond.

Read Next

September 4, 2025
Gavin Newsom has signed an executive order to accelerate the permitting of energy generation projects that could be set to lose IRA support.
September 4, 2025
The Czech national cybersecurity agency has warned that Chinese solar inverters represent a threat to the country’s data security.
September 3, 2025
Developers Alight Neoen have commissioned the 100MWp Hultsfred Solar Farm in Småland, southern Sweden.
September 3, 2025
Chinese solar manufacturer Trinasolar has signed a patent licence agreement with French module manufacturing startup Holosolis to use its TOPCon solar cell technology.
September 2, 2025
The Fraunhofer Institute for Solar Energy Systems (ISE) will build a pilot solar cell line in Germany to support US manufacturer Talon PV’s efforts to establish solar cell capacity in the US.
September 2, 2025
SMA Solar has forecast financial losses and further restructuring measures in 2025, as it responds to falling sales and a “challenging” market for residential and commercial renewable energy installations.

Subscribe to Newsletter

Upcoming Events

Solar Media Events
September 16, 2025
Athens, Greece
Solar Media Events
September 30, 2025
Seattle, USA
Solar Media Events
October 1, 2025
London, UK
Solar Media Events
October 2, 2025
London,UK
Solar Media Events
October 7, 2025
Manila, Philippines