AABC Europe 2015 - SESSTAM Symposium: Stationary Energy Storage System Technology, Application and Market - Session 3

Distributed Energy-Storage Systems

Session Chairman:

Dr. Michael Danzer studied electrical and energy engineering at Ulm University, Germany, and at Cardiff University, U.K. He received the Dipl.-Ing. and Dr.-Ing. (Ph.D.) degrees both in electrical engineering from Ulm University, in 2003 and 2009, respectively. His doctoral thesis was focused on the dynamics and efficiency of proton exchange membrane fuel cell systems. From 2009 to 2010, he was at A123 Systems, Inc., Boston, MA, USA, as a research scientist and validation engineer, where he worked in the field of battery characterization and fundamentals of battery operation. Since 2011, he is the Deputy Head of the Accumulator Department at the Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg (ZSW) in Ulm, Germany, where he leads the Battery System Engineering Group. Since 2011, he is also a Principal Investigator of the System Group at the Helmholtz-Institute Ulm for Electrochemical Energy Storage (HIU), Germany.

1. Residential Battery Systems - Operating Control Strategies Beyond Self-Consumption
   Matthias Vetter, Head of Department, PV Off-Grid Solutions and Battery System Technology, Fraunhofer Institute for Solar Energy Systems (ISE)
   

   The accumulated installed PV power in Germany reached end of 2013 a level of 36 GWp. This is a significant number as the load curve in Germany varies only between approximately 45 GW and 85 GW. These values show the demand for electrical storages, besides demand-side measures and grid extension. In Germany most of the PV systems are in the small and medium power range, are installed on buildings and are feeding into distribution grids, which are operated in certain regions already today at their limits. Integration of decentralized battery storages, e.g. lithium-ion batteries, is considered as a solution to solve this problem. Furthermore the gap between end-user electricity tariffs and the feed-in tariff is increasing year by year and is already above 12 €-Cents/kWh. Taking into account price reduction forecasts for advanced battery technologies like lithium-ion, the increase of self consumption of PV energy by integrating battery storages becomes a very interesting economic option in the near future.

   However, this presentation will show that the integration of battery storages in decentralized PV systems with the only optimization target “increase of self consumption” does not solve the problem of distribution grids with high solar shares. Advanced operating control strategies are needed to cover also grid issues and allow DSOs the access to flexibility options, which are enabled by the combination of PV systems with batteries. Within this presentation a selection of such approaches from different research projects will be described and evaluated.
   Furthermore the economics of battery storages can be improved when using battery storages for multiple purposes and therefore this presentation will conclude with a consideration of such options.

2. Experience with ESS Systems in the Field
   Andreas Piepenbrink, CEO and Managing Partner, E3/DC GmbH
   

   State-of-the-art battery performance and the innovative design of power electronics have created commercially viable storage systems. Combined with PV or co-generation at home, E3/DC has created significant volume of more than 1500 units in Germany based on professional, industrial production and a new product architecture within two years of series production in Germany.

   Combined with intelligent charging E3/DC has developed  technology to increase self consumption and to maximize autonomy.

   In this presentation E3/DC will show very good correlation between simulation and customer data with respect to annual time frames, load profiles, regional influences and solar performance. The simulation is based on VDI4655 including heat and electric power.

   The influence and impact of electric heating based on CHP (Co-Generation) and heat pumps will be presented as well as the impact of intelligent charging of electrical vehicle to maximize solar direct self consumption.

   Within the presentation the following practical design issues will be addressed:

   • Safety design with respect to ease of operation for installator and customer
   • Effect of multiphase systems versus single phase systems
   • First two year results of life time and efficiency of lithium battery systems
   • Anti deep discharge methods used by E3/DC
   • Solutions for island operation within grid based homes
   • Hybrid and farming field results of small and medium businesses

   Based on high quality, sound experience and excellent design of electric home storage systems
   including annual data and various sizes, types and architectures, E3/DC will give a practical survey on useability of electric home storage in the bandwidth up to 15000kWh consumption and up to 15000kWh production in the small power range of family homes and small businesses.
3. Lead-Acid Battery for Small Decentralized Energy-Storage Systems
   Bernhard Riegel, Head of Research and Development, Hoppecke GmbH & Co. KG
   

   Since its introduction early in 2013, the energy storage subsidy of the German government has encouraged many private householders to install battery storage systems. The objective of the energy storage law (EEG) is to increase the self-consumption of stored electrical energy from household owned PV Systems.
   For the traditional electrochemical storage industry this renewable energy regulation work was the starting point for a formidable expansion in the electrochemical storage business, not only in terms of sales, but also providing new impulses for R&D work. These included not only design and testing for new more effective cells types, but also the development of sophisticated cabinets and smarter battery managements systems.
   On the other hand these new promising home storage applications posed new challenges to the industrial battery manufacturers and retailers, now dealing with more customers in a manifold of applications with complex service requirements.
   In this context even traditional concepts like energy throughput and the well -known factors affecting performance and cell ageing, are to updated and optimized to achieve the expected service life of home storage (>10 years).
   Until now industrial batteries were usually owned and maintained by more or less skilled personnel. As a fact in the next future public knowledge on batteries is going to increase but there will be also more cases of faulty operations.
   The difference between today and the past is the diversity of the nowadays available electrical storage systems which range from conventional a flooded lead acid, VRLA advanced batteries up to novel Lithium storage chemistries. In our presentation we will compare the different VRLA systems on the European market and give some recommendations about important issues to be considered (battery management, life time, performance, and recycling) from a battery manufacturer´s perspective.
4. Modular Scalable Storage Solutions Based on LFP Technology
   Alexander Hirnet, Technical Director, Varta Storage
   

   Battery storage systems went more and more into the focus of interest in the last years. The propagation of renewable energy sources had increased the interest additionally. People are discussing how to increase the self-consumption of solar electricity by using a battery system. But a battery storage system is able to support many more applications like frequency control or stabilizing a low voltage grid. A battery storage system may be considered as a swiss army knife. To improve the profitability of such systems it makes sense to combine two or more application in one system. From application to application the requirements for a battery storage system can differ enormous. Also within one single application the requirements can differ from operation mode to operation mode. Considering a battery storage system used to increase the self-consumption of solar electricity one can observe a much higher charging power during day compared to the average discharging power over night. This fact has an enormous impact for e.g. to the efficiency of a battery storage system. The technical university of Munich (TUM) and VARTA Storage GmbH started a research project (EEBatt) to find answers for such questions. This presentation shows an system approach which is flexible adaptable to the customer needs and to the requirements of different applications.
5. Distributed Energy Storage to Maximize Self-Consumption of PV
   Matthias Hermes, Director of European Sales, Aquion Energy
   

   As distributed solar generation becomes increasingly commonplace around the world, there is a growing value proposition to store the excess power generated and dispatch it intelligently from at times of highest value. For this application, pairing energy storage that is tailored for high efficiency, long duration discharges offers the most flexibility to the application. Energy storage, as compared to PV, can be dispatched on demand to cover peak loads, in times when the grid is unavailable, or if sized properly, to fully island an entire home or installation without the need for traditional generators. Aquion Energy has been developing and has launched a novel aqueous hybrid ion energy storage system that is optimized for long duration applications such as maximizing the self-consumption of PV in locations around the world from Hawaii to Europe to Australia. This presentation will focus on the value that long duration energy storage can provide in these distributed applications when paired with PV and common installations in the field.