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Development of a highly efficient electrochemical storage unit for PV systems


The work described in this proposal aims at the development of a comparatively inexpensive storage battery, the vanadium redox flow battery, which is specially adapted to stand-alone PV-systems requiring seasonal energy storage. The availability of such a battery will significantly reduce the currently high overall system cost.
For seasonal energy storage, systems with high capacity are required. Classical secondary batteries, although capable of good energy efficiency in short term applications, suffer from self-discharge, limited system life and high cost. A combination of water electrolysis and fuel cells (hydrogen gas accumulator) suffers from low overall energy efficiency (=36%). Redox flow batteries offer the possibility to design a high capacity storage energy system adapted to the power of a solar home system at high overall energy efficiency (=90%). Furthermore, the cost oi the system is limited, since only the active material and a comparatively inexpensive storage tank is required to provide additional capacity. Fron all possible redox flow batteries, the all vanadium system promises the lowest technical risk in realization.
Within the project, suitable materials for high performance electrodes and low cost separators will be investigated. Furthermore, manufacturing technologies for modules and batteries of size up to 5 kW/100 kWh will be developed. Modules and batteries manufactured during the program will be subjected to bench tests and system tests in an existing PV-system. Optimized layouts for solar home systems will be developed as well. The partners are ZSW, Powercell and F.F. Lda, all of which have existing laboratory and testing infrastructures and long-term experience in the field of PV-systems and electrochemical energy storage technologies. ZSW is involved in several battery development and testing programs.
Particular emphasis is given to battery related materials research. Powercell has long-term experience in design and manufacturing of flow type batteries. F.F. Lda has experience in the layout of PV- and smallscale wind power systems.

Funding Scheme

CSC - Cost-sharing contracts


Zentrum für Sonnenenergie- und Wasserstoff-Forschung,Baden-Württemberg
89081 Ulm

Participants (2)

F.F. Sistemas de Energias Alternativas Portugal Lda.
Mesa Dinis
8670 Aljezur
Powercell GmbH
8680 Mürzzuschlag