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Vanadium-redox-flow batteries are an ecological alternative to store energy from domestic photovoltaic systems.

The lithium battery is widely used in domestic photovoltaic (PV) systems, but the technology remains problematic in terms of its ecological and humanitarian impact. Fortunately, alternative storage technologies are starting to come onto the market. An award-winning, start-up from Munich called VoltStorage has started selling solar storage systems for private homes that are based on vanadium-redox-flow electrolysis technology or VRF.

The so-called VoltStorage SMART system enables the consumer to store solar energy from their photovoltaic system around the clock, even when the sun isn’t shining, and makes energy self-sufficiency far easier and more attractive.

VRF was developed by the US space agency NASA in the 1970s but up until now has only been used in large-scale storage systems such as those used in solar and wind plants. The VRF battery has several advantages over the lithium battery: it is durable, fully recyclable and highly efficient and, critically, it is free of rare raw and conflict materials.

Vanadium is a readily available chemical element which is created during industrial iron production – it constitutes 25 percent of the smelting residue. And as iron will continue to be a vitally important material for the foreseeable future, vanadium will remain accessible. Lithium batteries on the other hand require not only the mineral lithium (the mining of which has a negative environmental impact) but also cobalt, which has become a source of conflict and humanitarian abuse in the countries where it is mined like the Congo.

VoltStorage has made it to the finals of the Start Up Energy Transition (SET) initiative for pioneers in energy system transformation and climate protection. The SET awards will be presented at the SET Tech festival on March 24th in Berlin. The project is powered by the German Energy Agency (dena) in cooperation with the World Energy Council (WEC).