In partnership with ADS-TEC, egrid applications & consulting GmbH implemented the "Allgaeu DESS" project in 2017 on behalf of the Allgaeu regional utility company Allgaeuer Ueberlandwerk GmbH.

The Nuertingen-based capacitor specialist had already supplied the first 2.5 megawatt battery storage power plant, which is distributed over five sites in the town of Kempten, and brought many years of experience in the industry to this project. With the addition of a sixth identical station, the power plant has since been expanded to a total of three megawatts.

At peak times, more renewable energy is generated in the Allgaeu region than can be immediately used. As one of the architects of the energy transition, egrid has taken up this challenge in Kempten. CEO Bernhard Rindt explains: "The number of days each year when wind and solar energy production around midday exceeds consumption is steadily increasing. By now the figure has reached 153 days, which is almost half the year." Previously, valuable energy has been sold to other countries and then bought back later at a higher price. The distributed energy resource system, with its high-performance lithium ion batteries from ADS-TEC, is an ideal, tried-and-tested solution to enable the region to use its own electricity and keep the power grids in balance.

The distributed energy storage system was initially distributed over five different sites. Located in the immediate vicinity of transformer stations and substations, the storage systems were installed in small concrete stations, and have successfully been in continuous operation since the start of 2018 at two locations in Kempten, Ursulasried, Nesselwang, Rubi and Dietmannsried. The five stations are an unsubsidised, independent initiative of the Allgaeu regional utility company, and are operated jointly with the power grid operator AllgaeuNetz as part of a multi-purpose application. The project was planned and implemented by egrid, a solution provider for decentralised and renewable energy supply in Kempten. In partnership with ADS-TEC and its many years of experience, the performance and capacities of the individual systems have been successfully optimised.

The main task of the storage system is to stabilise the integrated grid by providing a primary control reserve. Furthermore, the individual storage stations can also be operated as independent systems and perform functions such as supplying emergency power. The network thus provides system services at a local level. In March 2018, like all large-scale batteries from ADS-TEC, the entire system was approved immediately. The system has since been almost continuously popular on the primary control reserve market, and has always generated revenues matching its predicted profitability.

One important factor when integrating battery systems into the municipal infrastructure of Kempten has been the limited construction space. Accordingly, during the design phase, it was important that a solution should be as compact as possible and deliver particularly high performance. ADS-TEC Project Manager Patrick Weiss explains: "The performance and capacities of the individual systems were optimally adapted. Many customers value the compact design of our systems. Here in Kempten, miniature power plants that fit right into the urban landscape and their respective environments were created."

In December 2018, a sixth identical station commenced operation in the district of Oy-Mittelberg, the project planning for which was more cost-efficient and faster thanks to the previous project. In this case, the storage station is owned by an energy cooperative. The marketing and operation are being carried out as a service by Allgaeuer Ueberlandwerk GmbH. It is planned that the distributed energy resource should continue to be steadily expanded in future. The target market includes not only energy suppliers and cooperatives, but also commercial operations. Stationary battery storage stations can be used there for example to reduce the service and energy prices, for marketing control reserves, for improving the performance of an electric vehicle fleet, or in conjunction with emergency power applications. Short payback periods of just a few years can generally be achieved.

At all six locations, each battery storage station consists of three parallel, interconnected StoraXe Rack Storage Systems (SRS0112) from ADS-TEC; each station has a capacity of 112 kilowatt hours and an output of 500 kilowatt. That comes to a total installed capacity of about two megawatt hours, and an output of three megawatt. Each is combined with one 500 kilowatt inverter system (type AIC 500) from Gustav Klein in Schongau and with control technology manufactured by egrid, thus producing a readily scalable energy system.