Oz battery maker Redflow's residential product to land in March

Cue "plucky Aussie versus international juggernaut" tropes

Redflow, which started life building batteries for industrial applications like remote telecommunications facilities, says its first residential offering will land in March.

While it hasn't announced the price of installed end-user units, the company's latest investor update states the upfront battery-only cost is AU$800 per kWh, with the list price for its 8kWh ZBM-1 given as US$7,000.

That's broadly in line with what chairman Simon Hackett told Vulture South in August 2015, when he said that a $15,000 installed cost would be easily recoverable over ten years, since the channel will need a margin for delivery, installation and integration with existing solar kit.

The company's pitch to the residential market is that unlike both lead-acid and lithium ion batteries, Redflow's zinc-bromide kit supports 100 per cent discharge for its whole life. Lead acid batteries die quickly at such a deep discharge, and Li-ions are only good for 75 per cent discharge.

That means residential users – who presumably aren't as clued-up as a telecommunications carrier, for example – aren't in danger of destroying batteries with frequent discharges.

Redflow's explanation of its technology says this: "Since the ZBM is a flow battery, it features approximately 100 litres of water based solution of zinc-bromide salt flowing around in two separate hydraulic circuits. During the charge phase, the zinc is extracted from the liquid phase and plated onto carbon based electrodes. During the discharge phase, the zinc is de-plated and restored inside the solution."

The company says the battery is also safer than lead-acid: separating the fluid from the plates means there's no risk of thermal runaway, and the zinc-bromide solution is a fire retardant.

The company told the Australian Financial Review it's now putting the final design touches on the outdoor enclosure for the battery (sorry, it's not in a cute-and-sexy wall-mount package like the Tesla PowerWall), which it reckons will be about the size of a residential air-conditioning unit.

The AFR says Redflow shareholders will get the first bite of the cherry, and will also get discounts.

As Hackett told The Register in 2015, the company has been working hard to reduce its manufacturing costs. Its market update claims it's cut those costs by 15 per cent in the past year, and the batteries' lifetime cost per kWh has been cut by 50 per cent. ®

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