• Residential DER
  • Energy Storage
  • Battery Energy Storage

Thanks to sonnen, Large-Scale Residential Flexibility Becomes a Reality in Germany

Roberto Rodriguez Labastida
Dec 21, 2018

Solar 10

The use of residential flexibility (managing residential devices to provide flexibility services to the grid) has been possible in vertically integrated markets for some time. Bring your own thermostat demand response programs are becoming common in the US. New programs using other types of distributed energy resources (DER) like batteries are now operating at a large scale.

The same cannot be said for unbundled markets, at least in Europe. The fragmented nature of the market and the complex regulatory environment have kept residential DER outside the ancillary markets. In most cases, the cost of aggregating these assets is higher than the revenue they can generate.

sonnen Trailblazing

Possibly for the first time in Europe outside subsidized demonstration projects, sonnen, a residential energy storage company, has been granted permission to participate in ancillary markets, specifically the German Primary Control.

sonnen and its technology partner Tiko were pre-qualified by TenneT, one of the German transmission system operators, to aggregate residential customers’ batteries subscribed to its sonnenFlat tariff to create a virtual battery of 1 MW capacity.

Using artificial intelligence, the available capacities of the individual storage devices are recorded and the systems autonomously assign themselves to a virtual battery. With sonnen’s approach, all the approximately 30,000 sonnen residential batteries installed in Germany could be included in the concept. However, the home batteries would be combined into blocks of 1 MW capacity, which could then be used for primary control when there are fluctuations in the power grid. TenneT requires the virtual battery to provide or absorb 1 MW of power within 30 seconds.

What’s Next?

sonnen is proving residential flexibility can become a reality even with the added complexity of unbundled markets. The digitization and interconnection of residential devices with local energy markets creates considerable potential for flexibility from solar inverters, EV chargers, heat pumps, and even fridges, ovens, dishwashers, and more.

While the potential is there, only sonnen seems to be on the right path to tap the opportunity. sonnen has been working on it for some time now.

The company has been moving fast in the German market for residential batteries and including connectivity in battery systems, planting the asset base. By shifting from a pure manufacturer strategy to become an energy service company and specializing its product offering with the addition of sonnenCommunity and sonnenFlat products, sonnen gets the right to operate its customers’ batteries. sonnen has also worked to obtain pre-qualification with TenneT.

In other words, sonnen paved the way for itself, but not necessarily for anyone else in the industry. Its ability to operate different business models to tap into all the revenue streams available to DER is difficult to match. This will be to its competitive advantage as the market continues to develop.