sonnen

Who is sonnen?

sonnen is a German battery storage brand, founded in 2010 in the Bavarian village of Wildpoldsried. Two engineers, Christoph Ostermann and Torsten Stiefenhofer, set out to make clean energy affordable for everyone, not just early adopters. The company traded first as PROSOL Invest Deutschland, then as sonnenBatterie, before settling on the simple sonnen name in 2015.

In February 2019, Shell agreed to buy the company outright, taking a 100% stake at an undisclosed price. The deal gave sonnen the backing of a global energy major. However, the brand kept its own engineering team and Bavarian factory. That factory in Wildpoldsried remains sonnen’s headquarters and main production site. A second plant in Atlanta, in the United States, adds further capacity.

Today sonnen sells across Germany, the wider DACH region, Italy, the UK, Spain, Australia and the US. Germany remains its core market by a clear margin. However, the brand has steadily expanded its European and transatlantic footprint. In other words, sonnen is a European pioneer with genuinely international reach.

The sonnenBatterie eco product range

sonnen’s current flagship range is the sonnenBatterie eco, offered across a ladder of capacity tiers. Usable storage runs from around 5 kWh up to about 20 kWh. As a result, it stretches from a small flat to a large family home. Power output scales with size too. It runs from around 3 kW on the smallest unit up to about 8 kW. That top figure is the continuous AC output on the larger eco models.

Typical usable capacity tiers in the eco range include, approximately:

• eco 5 – about 5 kWh usable
• eco 10 – about 10 kWh usable
• eco 15 – about 15 kWh usable
• eco 20 – about 20 kWh usable

Every eco unit is a fully integrated system. It bundles the battery cells, inverter, power management electronics and smart software into one indoor cabinet. In other words, installers do not need to source and wire separate components. As a result, installation tends to be more standardised than with some modular rivals.

sonnen also sells the ecoLinx, a higher-specification variant aimed at larger homes and added smart-home control. In addition, there is the sonnenCore, a simpler, lower-cost entry point built for faster, more predictable installs. Meanwhile, sonnen Inc. in the US runs its own eco line-up tailored to American grid codes and incentive schemes. Model names and specifications can change by region and over time. So always check sonnen’s own site or an accredited installer for the exact figures for your postcode.

Key technology and the sonnenCommunity

At the heart of sonnen’s technology is lithium iron phosphate, or LFP, battery chemistry. LFP is prized for safety and long cycle life, rather than squeezing in the highest possible energy density. Combined with sonnen’s own battery management software, this is said to give each eco unit a long working life. In practice, that means well over a decade of service. That said, the feature that most sets sonnen apart is not the hardware at all. It is the sonnenCommunity, the company’s long-running energy-sharing network, together with the sonnenVPP, its virtual power plant.

How the sonnenCommunity works

Every household that buys a sonnen battery can join the sonnenCommunity. Members share surplus solar power with each other rather than simply exporting it to the grid at a low rate. In return, members can buy community power at prices below what a typical energy supplier charges. sonnen manages the trading, metering and billing behind the scenes, so the experience for a member stays simple. This model has also evolved to include electric vehicle charging. In some markets, it now extends to flat-rate electricity tariffs built around a sonnen battery. Terms vary noticeably by country though, so a UK buyer should check what is actually on offer locally.

The sonnenVPP and grid services

Launched in 2018, the sonnenVPP aggregates thousands of individual batteries into one large, flexible resource for grid operators. By early 2024, reporting suggested the network spanned more than 125,000 households across six countries on three continents. In practice, this means idle battery capacity can help balance the grid. It also smooths renewable output and avoids costly peaker-plant generation. sonnen has also piloted blockchain-based trading with grid operators such as Germany’s TenneT, aimed at cutting grid-stabilisation costs. For homeowners, the appeal is a sense that their battery is doing more than sitting in a cupboard. Beyond that, some markets offer financial rewards for enrolling, though these vary and are worth confirming before you buy.

Strengths and limitations

sonnen’s reputation rests on long-standing German engineering and one of the industry’s most developed energy-sharing concepts. That said, no brand suits every household equally well. So it is worth weighing the trade-offs before choosing a system. The points below summarise what tends to work in sonnen’s favour, and where buyers most often raise questions.

How sonnen compares to rivals

sonnen sits firmly in the premium tier of the home battery market, alongside German rival E3/DC. In a different way, so does Tesla Powerwall. Compared with E3/DC, sonnen leans harder into its community and VPP story. By contrast, E3/DC is often chosen for home-automation integration and hybrid inverter flexibility. Both brands share a reputation for German build quality and strong local installer networks.

Against Tesla Powerwall, the contrast is sharper. Powerwall is produced at far higher volumes, which tends to keep its price more competitive. In addition, Tesla’s app is widely praised for its simplicity. sonnen, by contrast, positions itself on bespoke service and a longer track record in the European market. Beyond that, there is the sonnenCommunity’s energy-sharing model, something Tesla does not offer in the same form. In practice, sonnen tends to suit buyers who value a specialist, European-engineered system with a community dimension. They are not simply chasing the lowest upfront price.

Within the UK specifically, sonnen is a smaller but well-regarded presence. It competes with better-known names such as Tesla, GivEnergy and Growatt. For buyers weighing the UK’s wider options, our other brand guides are a good next step. So is the HomeBattery.com calculator, for comparing real-world costs.

Common questions about sonnen