German non profit BalkonSolar e.V. and more than 500 citizens transformed 600 old solar panels from a tooth brush factory in the Black Forest into 300 new Plug-in-PV systems.
A generous donation of microinverters from Hoymiles and funding by the City of Freiburg’s Solar Summer program ensured that all these systems could be given to citizens free of charge.
„“We are proud to support this initiative for the third consecutive year and to see more citizens take part in giving used solar panels a second life,“ said Hoymiles CEO Dr. Yang Bo. „Renewable energy is not only about generating clean power, but also about using resources responsibly.“https://www.prnewswire.co.uk/news-releases/hoymiles-supports-solar-sustainability-for-third-consecutive-year-with-freiburg-upcycling-world-record-302895688.html
The event took place on Saturday the 26th of September 2026 on the school yard of a local Freiburg secondary school. The panels had operated for 13 years on the roof of the Interbros toothbrush factory in Schönau. This is the second time the BalkonSolar e.V. sets a world record in upcycling, the first was set in 2024 with 100 systems.
Citizens were given a package, made of two PV modules, each with 245 Wp, an inverter and cabling with a standard German Schuko plug to connect to the grid.
“Old solar panels do not have to be thrown away, but can be repurposed once they come down from the roof and easily and safely turned into plug-in-pv systems”, says Sebastian Müller, chair of the BalkonSolar Association. “We tried to adhere as close to the German technical standard, as possible.”, continues Sebastian Müller.
The event was opened by the state secretary in the German ministry for Environment Rita Schwarzlühr-Sutter and Freiburg’s deputy mayor Roland Meder and was under the patronage of Thekla Walker, the state minister for environment in Baden-Württemberg.
„Energy transition in Germany is working and fun”, says Chair of Balkon Solar Association Simone Herpich, “and it saves money and with balcony solar renters can participate in it as well”, she adds.
Many old solar systems are being taken down, either because the roof has to be repaired or they have reached the end of their feed in tariff and are replaced by new solar panels with a higher watt per square meter ratio.
Even old solar panels from the 2000s are still functioning and may have 30 to 40 more years of life in them. Degradation in these solar panels is around 10% of the original power potential. About 8% of the actual panels we used showed defects that made them unusable, some of them corrosion in the MC4 plugs and cables.
Several local organizations, such as Solare Zukunft, fesa and the Energie Agentur Freiburg provided logistical and technical support.
We estimate that there are about 5 Mio plug-in-solar systems in Germany currently in operation.
PIPV is legal in Germany, Austria, Switzerland, the United Kingdom, Poland, the Netherlands, Belgium and Greece, as well as in the US states of California, Utah, Colorado, Virgina, Connecticut, Vermont, New Hampshire and Maine.
We are working together with partners in the US and Europe to make it legal in more places, such as Finland.
The BalkonSolar Verein is a registered non profit, full of passionate Plug-in-PV enthusiasts from the German-speaking region with roots in Freiburg with more than 300 members.
For more Information about the Record in English: https://balkon.solar/worldrecord2026
More Information about DIY plug-in-solar: https://balkon.solar/news/2025/05/28/solar-secondlife-magazine-draft/
Press Release from Hoymiles: https://www.prnewswire.co.uk/news-releases/hoymiles-supports-solar-sustainability-for-third-consecutive-year-with-freiburg-upcycling-world-record-302895688.html