More Efficient Energy Consumption and More Stable Power Grids

March 02, 2014 by Jeff Shepard

Germany's Centre for Solar Energy and Hydrogen Research (ZSW) has initiated the research project called Sol-ion+ with seven partners from the fields of research and industry. Sol-ion+ aims to prove that the storage of solar energy offers many benefits not only to the end user but can also contribute to the stabilization of distribution networks. Such storage systems enable the consumer to draw significantly less energy from the public power grid and, instead, to use more electricity from their own photovoltaic system. The scalability of these systems also makes it possible to achieve higher outputs, so that they can absorb power fluctuations when used in the public power supply, thereby increasing the stability of the electricity supply.

The first phase of the project, which runs until the start of 2018, involves plans for the development of a storage system which can also be used in the consumer sector. Bosch Power Tec, as a manufacturer of storage systems for solar energy, is the project coordinator, entrusted with the task of developing this device. "The new generation of storage systems will enable users of the system to actively participate in future energy markets for the first time", says Dr. Armin Schmiegel, Project Manager at Bosch Power Tec. "The systems enable optimal interaction between the network and storage operators so that they can supply their self-produced power to the electricity exchange or, if required, purchase cheap electricity.”

Saft Batterien, the German sales company of the Saft Group, provides the battery technology: "Due to the interaction with the grid, the batteries have to work considerably harder here than in existing storage systems. Sophisticated lithium-ion technology and control engineering are necessary to ensure the highest degree of efficiency and a long service life" explains Holger Schuh, Managing Director of Saft Batterien GmbH in Nuremberg.

Stadtwerke Mainz Netze GmbH and Überlandwerk Groß-Gerau GmbH (ÜWG), two additional project partners, determine the specific demands on a grid-supporting system. A total of 17 storage systems are going to be installed as part of a field test in the ÜWG Stromnetze GmbH & Co. KG grid area in the Groß-Gerau district. "The future lies in innovative storage technology for the power grid. This is what makes our grid intelligent and enables the grid to meet demand for further flexibility" comments Jürgen Schmidt, Technical director of Überlandwerk Groß-Gerau GmbH, explaining the objective of this project. Stadtwerke Mainz AG, as the majority shareholder of ÜWG, supports the project.

"Renewable energy must and can make a significant contribution to system stability. Local storage systems, which can provide energy at any time and are operated by highly efficient power electronics and suitable algorithms, are virtually predestined for the task. The Sol-ion+ project takes up the important task of grid usefulness and implements it for real PV storage systems", says grid expert Lars Nehrkorn of ÃœWG.

The Fraunhofer Institute for Wind Energy and Energy System Technology (IWES), the Centre for Solar Energy and Hydrogen Research Baden-Württemberg (Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg - ZSW) and the ISEA of RWTH Aachen University support the project with the development of battery charging strategies and ageing models, analyses of system performance and grid-supporting management as well as field test supervision. Another important issue is the analysis of cost-efficiency.

In 2016, the field test will begin parallel to the installation of a combination of systems to support the grid and the installation of individual systems at the end user, and will have a runtime of 12 months. The project builds on the successfully completed "Sol-ion" project of 2012 and is also sponsored by the Federal Ministry for the Environment, Nature Conservation, Building and Nuclear Safety (BMUB). The runtime is four years.

The previous "Sol-ion" project ran from 2008 to 2012. The results and experiences gained from this project led to the development of Bosch's BPTS-5 Hybrid which was introduced in 2012. The participants include; Federal Ministry for the Environment, Nature Conservation, Building and Nuclear Safety, Bosch Power Tec GmbH, Saft Batterien, Fraunhofer Institute for Wind Energy and Energy System Technology (IWES), Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg (ZSW), Institut für Stromrichtertechnik und Elektrische Antriebe (ISEA), Stadtwerke Mainz Netze GmbH, and Überlandwerk Groß-Gerau GmbH (ÜWG).