Switzerland’s largest battery storage system has gone into action stabilising the electricity network for transmission grid operator Swissgrid, asset operator Alpiq has said.

First developed by NASA, flow batteries are a potential answer to storing solar – and wind – for eight to 10 hours, far beyond what is commonly achieved today with lithium-ion. In the first of a two-part special report, Andy Colthorpe learns what the flow battery industry faces in the fight for commercialisation.