Lithium or Vanadium: In Energy Storage, It's No Contest

Abstract

Vanadium vs LithiumIntroduction Already 25,000 home storage systems were installed in Germany until August 2015 due to German Solar Association (BSW Solar). Also in 2015, two German manufactures (Schmid Energy Solutions and Volterion) introduced home storage solutions using vanadium redox flow cells. So far, this battery type is not deployed for home storage. The question is how this technology will compete against more established ones. Flow batteries are expected to have very low variable costs (€/kWh). Furthermore they use a wider SOC range. On the other hand, efficiency is lower than for Lithium-based systems and fixed costs (€/kW) are rather high.

In this work, we examine how those properties influence the cost effectiveness for the use case of home storage. Therefore, we compare the performance of a Lithium and an allvanadium redox flow battery in a household simulation framework. A unique approach of combining a sophisticated multi-physic flow battery model with an advanced method of evaluating the economic contribution of a PV-home storage system is applied.

Uhrig Koenig Full PaperMethodology

The additional benefit of increased self-consumption by a battery system is determined over a period of 20 years using a temporal resolution of 15 minutes. Simulated households are characterized by their individual annual energy demand (1,000 to 10,000 kWh) and energy generation by rooftop PV-plants (500 to 15,000 kWh). For Lithium batteries, these simulations were carried out already. Here, a multi-physic model of a vanadium redox flow battery is additionally incorporated into the simulation framework. The model delivers SOC and power dependent efficiency as well as viable SOC and power limits. Obtained results are compared to the simulation run of Lithium-based systems in terms of optimal dimensioning and costs. Based on these results we evaluate the prospects of vanadium flow batteries in the home storage market.

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