Fraunhofer ISE is exploring medium-voltage technology that it believes can cut cable material by about 75%, lower installation costs, and improve solar PV project economics
It will test 2 pilot plants in Germany with 3 kV DC/1.2 kV AC inverters, including standard and high-voltage prototype modules
Project findings will guide quality assurance and testing concepts for medium-voltage PV systems
Fraunhofer ISE has unveiled the world’s ‘1st’ medium-voltage solar PV power plants with a 3 kV string inverter, as it explores ways to reduce the use of raw materials, including copper and aluminum.
“The move to medium voltage is a key lever for reducing the demand for copper and aluminum in large-scale photovoltaic power plants and thus for the economic viability of the projects,” explains Fraunhofer ISE Project Manager Felix Kulenkampff.
The team explains that large 50 MW solar plants, for instance, require cables in the ‘3-digit kilometer range’, driving up demand for copper, which is expected to be in short supply, pushing up its prices. This, in turn, pushes up project costs. Aluminum is being used as a substitute for copper, but it comes with high carbon emissions.
Switching to medium-voltage systems, it adds, can cut cable material by about 75%, reduce installation costs with thinner cables, and allow doubling of the connected load of transformers and substations with fewer units required, thus improving project economics.
Under its PVgoesMV research project, the German solar PV technology research and development firm will construct and test 2 pilot solar PV plants with 3 kV inverters. Over the next 3 years, it will run these projects in an attempt to demonstrate the technical feasibility and economic viability of medium-voltage technology for large-scale solar power plants.
These projects are planned to come up in Germany’s Baden-Württemberg and Rhineland-Palatinate. Each will have a connected load of approximately 135 kW. The team will operate these projects at 3 kV on the DC side and 1.2 kV on the AC side. The institute plans to use its in-house-developed medium-voltage PV inverter based on high-blocking silicon carbide semiconductors.
For one of these pilots, the team plans to test standard solar modules with 1,500 V and center point grounding. The other will use a 3 kV string with PV module prototypes developed for a higher voltage class. Funded by the German Federal Ministry for Economic Affairs and Energy, the project started in December 2025.
Fraunhofer ISE is working on this pilot with its project partners across the supply chain, including companies such as Hanwha Q CELLS GmbH, Infineon Technologies AG, and Zimmermann PV-Steel Group GmbH, among others.
Findings from these pilots will enable the team in its endeavor to develop a quality assurance and testing concept for medium-voltage PV systems.
Catch Fraunhofer ISE’s Head of Technology, Jochen Rentsch, will be speaking at the TaiyangNews Solar Technology Conference India 2026 (STC.I 2026) on February 5 and 6 in Aerocity, New Delhi. He will share insights on the solar cell research and outlook for solar PV technology, from TOPCon to perovskites, and talk about upstream manufacturing. This 2nd edition of the TaiyangNews physical conference will also have banks, investors, and policymakers in attendance. Register for the event here.