Sonnen launches trade-in program for old solar battery storage systems regardless of condition or manufacturer

Sonnen is launching what it claims is Germany’s first battery storage exchange program. The company is offering households that installed a photovoltaic storage system by December 31, 2020, the opportunity to replace their old systems with a new Sonnen Battery – regardless of the condition or manufacturer of the existing unit.

Under the initiative, Sonnen is introducing a trade-in bonus modeled on the automotive scrappage scheme. Households can receive a credit of up to €2,800 toward the purchase of a new Sonnen storage system. The minimum bonus is €500 for a Sonnen Battery with a 5.5 kWh capacity, increasing in tiers up to €2,800 for systems with 33 kWh of capacity.

The promotion is initially set to run until the end of the year, but a repeat in 2026 is possible if demand is strong, a Sonnen spokesperson told pv magazine. According to the company, the program targets around 270,000 existing storage owners. Replacing and networking these systems could add roughly 2.7 GW of additional flexible capacity to Germany’s electricity grid.

“A huge, untapped power plant potential lies dormant in Germany’s basements,” said Sonnen CEO Oliver Koch. “Even today, networked home storage systems have proven their ability to stabilize grids and prices. The prerequisite, of course, is that the bureaucratic hurdles still slowing down grid-friendly use of storage systems are removed.”

The exchange program allows early adopters of home storage to upgrade to devices with higher capacity and advanced smart features that were not available before 2020.

When asked about costs, Sonnen declined to provide specific pricing. “Since we don’t sell directly to end customers and prices are set by our partners, we cannot give a specific figure,” a company spokesperson said. “End customers can contact our partners for pricing details. In most cases, the new storage systems will be cheaper than older ones, while offering significantly better performance and more features.”

“No warehouse clearance sale”

Sonnen emphasized that the initiative is not about reducing inventory but expanding its virtual power plant (VPP). “From the perspective of the electricity grid, we are transforming previously unavailable power into grid-supporting power,” the spokesperson explained.

Although 2025 was not a strong year for residential PV, Sonnen said its storage sales met expectations and have been rising again since early 2025, signaling a “stable recovery” after the 2024 slowdown.

“This promotion is therefore not a clearance sale, but a targeted growth initiative in a new market segment that has now reached a significant size,” the spokesperson added. “We aim to attract new customer groups and strengthen our growth. Retrofitting battery storage systems to existing PV installations is becoming an increasingly interesting market that we are consciously addressing.”

All replaced storage units will be professionally disposed of, with most materials to be recycled, according to the company.