Households replacing power stations in Germany - sonnen is putting the largest virtual battery of its kind into operation creating the power grid of the future

Households replacing power stations in Germany - sonnen is putting the largest virtual battery of its kind into operation creating the power grid of the future

For the first time, sonnen, an eCAPITAL portfolio company, is providing balancing power for the energy market by means of residential energy storage systems networked across the whole of Germany. The sonnen virtual battery, which is now online, is currently the largest of its kind that is able to compensate for fluctuations in the power grid. As a result, German households are now in a position to take over all the tasks of conventional power stations.

eCAPITAL portfolio company sonnen together with its technology partner, tiko Energy Solutions, has obtained pre-qualification from the transmission system operator TenneT to provide primary balancing power using its Germany-wide network of residential battery storage systems.

In this way, sonnen is providing the energy market with the largest virtual battery currently available consisting exclusively of individual residential energy storage systems. Now along with supplying its customers with clean and locally-generated electricity, sonnen is now able to provide flexibility for the energy markets and expanding its offering to act as the utility of the future. The virtual battery will be used to compensate for fluctuations in the power grid among other services.

“As a young company, we are very proud to be writing energy history. In doing so, we are showing that our customersin Germany can assume all of the functions that were previously reserved for large power stations. They can create and store energy and also ensure the security of supply within the power grid. The shift from the old energy system with central power stations to a new distributed system with the people at its core, is finally coming about as a result", says Jean-Baptiste Cornefert, Managing Director of sonnen eServices.

The sonnen virtual battery takes a unique approach. It consists of thousands of individual energy storage systems installed across the entire country, each of which can be used to manage energy consumption for individual households. In addition, when fluctuations arise in the power grid, these batteries independently arrange themselves into a large-scale virtual battery. Since each sonnenBatterie has a different state of charge the large number of individual batteries will be aggregated into blocks starting at 1 MW, which are then made available to the energy market. During TenneT's certification of the virtual battery, it had to first discharge one megawatt of power to the grid and then re-charge the same amount back from it within 30 seconds. With the passed test, the virtual battery has qualified for participation in the so-called primary operating reserve market.

The power from the virtual battery can be used to rapidly compensate for short-term fluctuations in the power grid within the shortest possible time. If deviations arise in the grid frequency of 50 Hz, the energy storage systems are able to automatically, and in a matter of seconds, either supply energy to the power grid or take energy from it - depending on what is currently required. Until now, it has mainly been CO2-intensive power stations that have been used for this primary balancing power; sonnen’s networked residential energy storage systems are helping accelerate the removal of these power stations from the grid in Germany.

“We are proud of the fact that with sonnen we are now able to implement our virtual power plant technology. This is pioneering work for the German market; it means that energy storage systems are able to deliver the two-fold benefits of managing personal consumption while providing various services to the energy market. With sonnen, we have now been able to show, among other things, that it is also possible to provide primary balancing power in Germany by means of home energy storage systems," says Fréderic Gastaldo, CEO of tiko Energy Solutions.

"The ability of networked battery storages operating as a virtual power plant to stabilize the grid in the event of frequency fluctuations is another step on the way to a greater system integration of renewable energy," said Lex Hartman, CEO of TenneT. System services that serve to stabilize the power supply would previously be provided mainly by conventional power plants. With the increasing share of renewable energies in electricity generation, renewables will need to take on a greater responsibility, Hartman said.

Pre-qualification for the primary balancing power market is subject to the most stringent of requirements in terms of technology and safety in the energy market. By achieving the highest level of certification, sonnen’s network of residential energy storage systems is destined to provide further services within the power grid. In contrast to large stationary storage systems or fixed power stations, sonnen’s flexibly distributed virtual power plant can be deployed in nearly every location in Germany.

With its sonnenFlat offer, sonnen has been providing a specially developed electricity tariff in Europe, whereby energy storage system owners are able to benefit from network services. In exchange providing storage capacity, they receive a certain amount of free electricity. For the owners of sonnenBatteries, the use of renewable energies is therefore more profitable.

sonnen has around 30,000 sonnenBatterie systems in Europe, each with a capacity between 5 to 15 kWh. The total network has a capacity of up to 300 MWh and the potential to supply around 120,000 households with electricity for one hour.

About sonnen
At sonnen, we believe clean, affordable, and reliable energy for all is one of the greatest challenges of our time. sonnen is a proven global leader in intelligent energy management solutions that provide greater energy control for residential customers through increased solar self-consumption, reduced peak energy usage and reliable backup power during outages – contributing to a cleaner and more reliable energy future. sonnen has won several awards for its energy innovations, including the 2018 Fast Company Most Innovative Companies in Energy, 2017 Zayed Future Energy Prize, MIT's Technology Review's 50 Smartest Companies in 2016, Global Cleantech 100 for 2015-2017, Greentech Media's 2016 Grid Edge Award for innovation, and Cleantech's 2015 Company of the Year Award in both Israel and Europe.

About TenneT
TenneT is one of the leading electricity transmission system operators in Europe. With around 23,000 kilometers of high and extra high voltage connections in the Netherlands and Germany, we ensure a secure supply of electricity to 41 million end-users. With around 4,000 employees, TenneT continues to develop the Northwest European energy market as a responsible pioneer and, as part of its sustainable energy supply, is increasingly integrating renewable energies.

eCAPITAL entrepreneurial Partners AG is a Münster-based alternative investment fund manager (AIFM) in accordance with EU-directive EuVECA. As a leading German venture capital firm, eCAPITAL has supported innovative entrepreneurs in future-oriented industries since 1999. The firm focuses on rapidly growing companies in the areas of Software / IT, Cleantech, Industry 4.0 and New Materials. Currently, eCAPITAL manages six funds with a total of 220 million euros under management. Find more information under

sonnen GmbH
Mathias Bloch
Am Riedbach 1
87499 Wildpoldsried, Germany
Tel.: +49 8304 929 33 426
Email: m.bloch(at)

TenneT TSO GmbH
Ulrike Hörchens
Bernecker Str. 70
95448 Bayreuth, Germany
Tel.: +49 921 50 740 4045
Email: Ulrike.Hoerchens(at)

eCAPITAL entrepreneurial Partners AG
Sylvia Richter
Hafenweg 24
48155 Münster, Germany
Tel.: +49 251 703 767 0
Email: info(at)