Caterva, a startup cofounded and partially supported by Siemens, has developed a revolutionary energy management system. The system makes it possible for homes outfitted with photovoltaic systems to rent out part of their battery power to network operators. The operators, in turn, pay the homeowners to temporarily store excess regeneratively-produced energy, which can be used to stabilize the network, thus supporting homeowners, network operators, and, of course, Caterva.
In his rural home in Bavaria, Andreas Seubert has a 1.8-meter high steel cabinet in the basement that houses stacks of lithium-ion batteries on one side, while the other side contains inverters, a smart meter, electronic switchgear, and a card-size circuit board with a processor and a mobile communications unit. Together with a number of solar panels on the roof, the systems provide an impressive example of what experts mean by decentralized power distribution.
If Germany succeeds in its energy transition, energy storage systems (ESS) such as the one in Seubert’s basement will become an important part of a sustainable energy network in the future. That’s because such systems will help keep grid frequency stable and offset power deficits when the sun isn’t shining and the wind isn’t blowing. This task is currently still performed by conventional power plants, such as quick-start gas-fired power plants.
The Caterva solution consists of lithium-ion batteries and a mobile communication network. When linked with units in other buildings, they form a virtual storage system.
However, Caterva, a young Munich-based company, is demonstrating that there is also another way. “Caterva is the Latin word for swarm,” says the company’s managing director, Markus Brehler. The swarm principle is simple, and involves storing the electricity produced by photovoltaic modules such as those on the roof of Seubert’s home in lithium-ion batteries. Each cabinet of batteries has a total output of 20 kilowatts and a capacity of 21 kilowatt-hours (kWh). Cabinets in buildings throughout a region are connected through the grid, creating a swarm or virtual storage system with an output of over one megawatt. The cabinets are controlled via mobile radio, and electronic systems in the cabinets allow a control center to tap or recharge Caterva participants’ batteries. If there is demand for additional electricity in the grid, “the control center draws power from the swarm of batteries” in order to offset fluctuations, Seubert explains.
This innovative concept was originally developed by Siemens Novel Businesses, and then enhanced by various departments at Siemens Corporate Technology until the basic version of the swarm software was completed. Experts at SNB also helped establish Caterva, because it is their job to create new companies whenever a promising business idea cannot be further developed by Siemens AG as well, as quickly, or as flexibly as by an external firm. Before becoming the managing director of Caterva, Brehler gained extensive experience at another Siemens spinoff: EnOcean GmbH. Siemens will continue to support Caterva in many ways in the future. For example, it connects the cabinets to all of the hardware and is also a minority shareholder in the company.