Electricity Storage Systems in Medium- and Low-Voltage Networks

This paper presents the results of the ETG (Energietechnische Gesellschaft) Task Force "Energy Storage in Distribution Networks". The principle result of the former ETG study "Energy Storage for the Energiewende - Need for Storage Systems and Impacts on the Transmission Network in Different Scenarios until the Year 2050" is, that due to energy economic reasons, storage systems are only needed in the transmission system for a very high penetration of renewable energy sources. The research - and therefore the mentioned conclusion - is limited to the application field of balancing the fluctuating power feed-in from renewables and demand. Other fields of application for electricity storage systems, such as the provision of ancillary services or services for private and commercial customers, have not been analyzed. Therefore, the ETG Task Force "Energy Storage in Distribution Networks", which started working in March 2013, was dealing with the arising new questions and challenges. The final report has been published in June 2015. Some of the main results are presented in this paper.