Redflow Introduces Its 10kWh ZCell Battery Storage System In Australia

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Originally published on RenewEconomy.

Australian battery storage developer Redflow on Wednesday launched its household battery storage product – dubbed the “ZCell” – which it expects to take on Tesla and other high profile international brand names in what is expected to be the first mass market for battery storage in the world.

redflow-logo-zcell-284x300The 10kWh ZCell will sell for between $17,500 and $19,500, pricey by comparison with its competitors. But Redflow says its ability to discharge 100 per cent of its power, and its longer life, and its greater size, means that its delivered cost of energy will match its rivals.


“ZCell breaks many of the rules that apply to legacy batteries, making it ideal for the home market,” said Simon Hackett, the IT guru who has emerged as executive chairman of Redflow and its largest shareholders, and who has taken responsibility for writing in the “smarts” that will enable the battery to integrate with home energy systems.

“ZCell lets you discharge 100 per cent of its total stored energy every day, whereas other battery types can require a significant amount of their underlying storage capacity to be locked out to prevent battery damage and to extend battery life. ZCell is a unique flow battery that loves to be fully charged and discharged daily.”

Hackett expects the market for battery storage to “explode” – due to a combination of Australia’s high electricity prices, its high level of rooftop solar installations, a desire for more “independence” from utilities, and because people care about the environment.

Hackett says he is the biggest fan of the Tesla brand in Australia – having bought its $250,000 roadster and several models of its Model S electric vehicles. And he says that Tesla’s marketing success for its Powerwalls has been a “catalyst” rather than the cause of huge consumer interest.

But he says that Redflow has a better battery storage product for households.

“We have got a better technology for stationary storage,” Hackett told RenewEconomy in an interview. “Tesla will sell a hell of a lot of Powerwalls. But it’s not a matter for them to lose or for us to win.”

Hackett says the reason for his optimism is the “durability” of the Redflow battery. Unlike competitor batteries, it can fully discharge, is long-lasting, and does not have overheating issues.

Residential installations for the ZCell battery will start mid year, initially via an introductory rebate offer to eligible shareholders in the ASX-listed company. Full details of ZCell and the opportunity to reserve a ZCell battery are available at

Redflow says its battery storage product, using zinc bromine flow battery technology developed at the University of Queensland, and then later through the company, will allow people to ‘timeshift’ solar power from day to night, store off-peak power for peak demand periods and support off-grid systems.

The Australian company is playing hard on its durability, emphasising the fact that ZCell is “warranted to deliver its full 10kWh of stored energy each day for as long as 10 years.” During that period, it says, rival lead acid and lithium batteries can lose a significant portion of their storage capacity.

It is also emphasising the fact that the materials in the battery – mostly plastic, aluminium and steel – are easily recycled. Its fluid electrolyte, less environmental benign, can be re-used or repurposed. And there is no risk of explosion or “thermal runaway” that can afflict other products.

Redflow says the core of ZCell is a Redflow ZBM2 flow battery, which will sit in a “custom-designed outdoor-rated enclosure” that sits on the ground, connecting to a battery inverter/charger unit that delivers stored energy to the home.

redflow-launch-590x371The battery is managed and protected by a sophisticated on-board computer control system, written and developed by Hackett’s IT team at his company Base64.

Hackett expects the first large batch of systems to arrive in the country mid-year.

“Redflow does not set the total installed system price as we supply only part of the overall system,” he said in a statement.

“Final system cost will be set by your system installer, depending on your requirements and upon any additional items, such as solar panels, you may elect to include. We expect the fully installed cost of a 10 kWh ZCell-based energy storage system will start from $17,500 – $19,500 including GST.”

He said it was easy to construct larger systems that use multiple ZCells where more energy is required, such as in larger homes or commercial installations. The ZBM2 core battery is already delivered in systems all the way up to Redflow’s grid-scale Large Scale Battery (LSB), which features as many as 60 batteries in a single LSB.”

Redflow is installing some exemplar ZCell systems between now and June and is also inviting energy storage system designers and installers to register their interest to become a qualified installation partner at It is also offering eligible Redflow shareholders a $1000 rebate for installation of a ZCell-based energy storage system.

Reprinted with permission.

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Giles Parkinson

is the founding editor of, an Australian-based website that provides news and analysis on cleantech, carbon, and climate issues. Giles is based in Sydney and is watching the (slow, but quickening) transformation of Australia's energy grid with great interest.

Giles Parkinson has 596 posts and counting. See all posts by Giles Parkinson

7 thoughts on “Redflow Introduces Its 10kWh ZCell Battery Storage System In Australia

  • More options are better. Hopefully they can continue to bring the cost down. It seems for flow batteries the costs are largely driven by power output – increasing energy storage being a matter of larger tanks and more relatively-inexpensive electrolyte.

  • This one is interesting as the first flow battery aimed for home use. Its pricey and some of the claims don’t add up, like the one about cooling. It does have a fan.
    The thing is so new that the website keeps explaining that they are doing tests and don’t have answers.

    There are references to some of the tech problems like dendrites and solution temperatures, gelling, etc., on many sites. Efficiency is notably absent from the company description, but the paper shows it in the range of about 60 to 70%. ZBr flow batteries have some unique characteristics. They need to do something called a “strip cycle” every 1 to 4 cycles to get them ready for another cycle. It removes excess zinc from the stack and takes 0.5-2 hours. This is probably not a problem for grid tied residential storage.

    Its a typical flow. ZBr flow is expensive.–bromine_battery

    Its output is 48V DC which puts it in a different storage place vis a vis solar. Grid tied solar has gone for higher voltages to avoid heavy cables and cable losses. Its odd that Redflow has a lead acid mimicking mode thats a throwback to parallel off grid systems of long ago. This could be interesting for some off gridders. Vensonata? Anyone?

    Also requires a MPPT. The description shows AC and DC coupling. AC is easy, but may require duplicate inverter function, an extra cost.

    DC coupling is available if the user starts from scratch, but its incompatible with some existing systems.

    Right now there is only one compatible inverter, the Victron. Its interesting and provides multiple outputs so one can do both backup and/or grid tied. I like that.

    As to competing with Tesla, this claim gets old fast. Me2 with a Me2 claim. How dull is that. You would think competitors could spice up their message better than that.

    I don’t think there is a direct comparison. Its more expensive, and has different characteristics. Its certainly heavier at 240kg.

    All in all, an interesting entry, and gives a storage alternative. This might be an interesting option for off grid use that requires frequent deep discharge. Deep discharge is less of an issue for grid tied applications, but it remains to be seen if it justifies the higher cost.

    Redflow has been around a while. This one has the appearance of throwing the hat into the ring since the gauntlet and challenge have been set. Its now or never for competitors. There is a widening market, but competitors need to jump in before the ship sets sail and keep up with technology.

    • 61cents U.S. kwh. A killer. Of course all Australian batteries are at least twice the cost of the U.S. for the same product. Aquion (sodium) is probably a better choice if they have arrived in Aus. The LG RESU (lithium) is one third the price per kwh in the Australian market.

      • I noticed a few more things. Redflow says you have to keep the unit within its operating window or it voids the warranty. There are restrictions. Might not be a problem, but needs to be reckoned with for comparisons. Also, the working fluid is not harmless.

        “3. Regular Maintenance (0.5 hour period from 19.2 to 19.7


         After discharge is completed, excess zinc is stripped

        from the ZBM. The user should allow two hours for a

        full regular maintenance to be performed on a healthy


         When required, the ZBM will automatically prevent

        further charging and only allow discharge to occur. The

        ZBM will then continue to discharge until it is

        sufficiently discharged to engage the strip contactor.’

        That last part is its normal stripping cycle that removes excess zinc. That part is probably OK as it is done automatically.

        Can you give some details on the LG RESU? Sounds like you have analyzed it.

    • eveee, I asked you to stop reading stuff in Wikipedia. The proper name for the Redflow battery is a Hybrid flow battery. It is a not a true flow battery and has had issues in the past and still does. But some of your statements contain outdated information. It doesn’t have to strip the electrode every 1-4 cycles now. But even once a week (which is the case) is enough of an inconvenience and would decrease opportunities for revenue.

      Are you telling me you can couple a lithium battery to a solar array without the use of a inverter, or converter with a MPPT or an optimizer on the panel side?

      I beg to differ

      It also has advantages that Tesla doesn’t that they can take advantage of. Redflow could provide residential support and grid interplay in the ISO markets if the rules allow. they could bid into the CAISO daily ancillary markets to pay for itself

  • I wonder when / if they will get these in the US.

  • I can buy FIVE 7kWh Tesla Powerwall units for the price of a ZCell and have money left over. That’s a total of 35kWh (32 usable) of storage. Let’s pretend the capacity degrades by 20% then I’d only have 28kWh left. hmm last time I checked 28 kWh is far greater than 10kWh.

    The equivalently priced Lithium Ion solution would have to degrade over 70% to equal the capacity of the ZCell. ZCell is simply not cost effective and not a proven technology.

Comments are closed.