The road to high voltage, for more efficient and sustainable photovoltaics, requires technological developments in solar panels. The CEA is a pioneer in this field, with unique results and equipment.
High-voltage photovoltaics, the next step ?
Published on 07/21/2025
Photovoltaics will be the world's leading source of electricity by 2050 (source: IEA). However, even the largest solar power plants of several gigawatts currently operate at low voltage, which limits their power, complicates their design and increases wiring costs. At the same time, the integration of photovoltaics on existing linear infrastructures (roads, railways, canals) is gaining in interest. But these configurations increase the power to be transmitted, and therefore the currents involved. Moving from the usual 1,500 Vdc to 3,000 Vdc reduces losses by 50% and saves 47% in copper and aluminum for decentralized systems (1).
In light of these challenges, a technological evolution towards direct connection to high voltage is necessary for more efficient and durable photovoltaic systems.
The CEA has been a pioneer in this field, with initial work beginning in 2014 under a CRE (French Energy Regulatory Commission) call for projects aimed at developing photovoltaic panel and system designs capable of operating at 3,000 Vdc. A demonstrator was implemented on the roof of INES.
Although the industry showed interest as early as 2016—evidenced by several publications from research centers and industry players—it became clear that the market was not ready. The priority at the time was to deploy large volumes of systems based on proven technologies.
Today, the photovoltaic community appears to have reached a consensus and is ready to move toward high voltage. This is reflected in a forthcoming standard (IEC-63543) addressing panels and systems operating at voltages up to 3,000 Vdc. It is also reflected in research and innovation projects supported by the European Commission and leading industrial players such as Nexans, Schneider Electric, SNCF, and CNR.
For more than 10 years, CEA has reinforced its position as a forerunner and continues its work through projects such as TIGON, Raccor-D, and Medium.
The objective is not only to optimize panel design for 3,000 Vdc operation but also to prepare for even higher voltages—6,000 Vdc and 9,000 Vdc—which SNCF considers optimal for the renovation of regional and secondary rail network lines.
As part of the Raccor-D project with SNCF, CEA has demonstrated a stabilized architecture of photovoltaic panels operating at 3,000 Vdc.
With the increase in applied voltages, modules are exposed to higher risks of degradation related to the PID (Potential Induced Degradation) phenomenon. Selecting the most suitable panel components—such as glass, encapsulants, and cells—requires advanced characterization and the development of dedicated testing equipment.
For example, PID tests conducted at 3,000 Vdc are helping to deepen the understanding of charge movement mechanisms under electric fields, paving the way for more robust and long-lasting photovoltaic systems.
Upstream work is needed to understand the specific degradation mechanisms at these voltage levels, along with the implementation of characterization tools (developed by CEA) for both laboratory and outdoor use.
Eleven photovoltaic panel models—nine commercial products and two prototypes developed by CEA—were subjected to a test sequence that included stabilization under illumination, PID testing at ±3,000 Vdc (-3,000 Vdc then +3,000 Vdc), and PID testing at ±6,000 Vdc (-6,000 Vdc then +6,000 Vdc).
At the end of the testing sequence, heterojunction technology panels and those specifically designed by CEA for high voltage—using carefully selected architectures and materials—showed power losses below -2%, stable electroluminescence images, and the lowest PID sensitivity.
It should be noted that not all heterojunction panel references behaved the same way. Other panel types showed either significant power losses or clear signs of PID-related degradation.
Our laboratories continue to work toward addressing 6,000 and 9,000 Vdc with panels that withstand these high voltages while remaining compliant with IEC standards. This work relies on simulations to help optimize designs while maintaining standard panel dimensions.
When it comes to high voltage, conversion is also a key topic. See related developments in the TIGON project (Lien vers publi du 01/04/2025) and DC-Power project (lien vers publi du 02/08/2024).
- Upcoming System Technology in Medium Voltage for High-Power Charging and Large-Scale PV-Plants, Dirk Kranzer, Henrike Köhler, Andreas Hensel Fraunhofer ISE