Home Battery Storage Pioneer Sonnen Files for Insolvency Just Two Months After Shell Sale – Group Revenue Slumps 55 Percent, Heavy Losses
Wildpoldsried (Germany) – German home battery storage pioneer Sonnen has filed for insolvency. Energy group Shell sold the company to investor Tiven only in August.
Sonnen Files for Insolvency – Operations Are to Continue
Sonnen GmbH, based in Wildpoldsried in the Allgäu region, filed for insolvency on Thursday (October 22, 2026). The company is part of an international group with entities in several countries. According to information from Handelsblatt, individual entities are to be wound down, while others are to be restructured through insolvency proceedings under self-administration. According to the same information, only one production site is to be retained going forward.
According to the report, around 400 employees at the company’s headquarters in Wildpoldsried were informed of the filing. Existing business and services are to continue for the more than 150,000 customers. Which parts of the company will be retained in the long term remains open for now.
Heavy Losses Already Under Shell – Financing Has Been an Issue for Years
The Sonnen group’s economic difficulties existed long before Shell sold it to investor Tiven in August 2026. According to information from Handelsblatt, the group’s revenue fell by around 55 percent in 2024 compared with the previous year.
Sonnen GmbH’s 2024 annual financial statements show a net loss for the year of around EUR 106.6 million. The figure relates to the German stand-alone entity, not the entire Sonnen group.
The audited 2023 annual financial statements already pointed to a going-concern risk. According to the statements, the continuation of Sonnen GmbH depended on financial support from its parent company. In June 2024, Sonnen Holding GmbH pledged financing of up to EUR 49.2 million through the end of 2025. It was in turn dependent on financial support from the Shell group.
Under Shell, Sonnen sought to improve its economic situation with the “Sunrise” restructuring programme. Shell had acquired Sonnen in 2019. Since August 2026, the new owner has been Tiven, the family office of Aurelius co-founder Gert Purkert. Aurelius WaterRise supported the restructuring.
Problems in the Home Storage Market: Further Insolvencies and Withdrawal from New Business
Sonnen is not the only German storage manufacturer facing economic difficulties. Konstanz-based home storage and inverter manufacturer RCT Power filed for insolvency in September 2026. At the beginning of October, insolvency proceedings were opened for VARTA Storage GmbH, which offers, among other products, battery storage for private photovoltaic systems. EnBW subsidiary Senec had already announced in July that it would stop taking on new customers after heavy losses and an unsuccessful search for an investor.
The developments come amid shifting competitive conditions in the home storage market. According to an analysis by P3 and RWTH Aachen, the combined share of the five largest manufacturers in newly installed storage capacity in Germany fell from just under 55 percent in 2024 to just over 45 percent in 2025. Sonnen still achieved a market share of 3.3 percent in 2025.
Chinese manufacturers hold a strong position in the German home storage market. BYD remained market leader in 2025 with 16.5 percent, despite a declining market share. While Huawei and Sungrow also lost share, other Asian suppliers such as Anker and Fox ESS gained share.
Sales structures are also changing. Large installation companies such as Enpal and 1Komma5° work with selected storage manufacturers and increasingly offer standardised system solutions. Enpal, for example, cooperates with Chinese manufacturer Fox ESS. 1Komma5° now also relies on its own storage technology while integrating battery systems from other manufacturers into its energy management platform. As a result, procurement decisions by large installers are becoming more important for storage manufacturers’ market positions.
Source: IWR Online, 23 Oct 2026
