Redflow takes on home storage market with ZCell flow battery system


Source: Featured in EcoGeneration Wednesday 30/03/2016

Australian battery storage company Redflow today launched its first residential battery solution, the ZCell, a compact, modular 10 kWh energy storage system based on its zinc bromide flow battery technology.

In a statement, Redflow hailed the versatility, safety and robustness of its product, saying the ZCell delivers the proven performance of its industrial-scale ZBM2 battery in an attractive, easy-to-install enclosure.

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The product is designed to support daily cycling, time-shifting of solar power and off-grid applications.

Redflow says the first Australian installations of the ZCell will start mid-year, with international availability to be announced in coming months. The company 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

Redflow Executive Chairman Simon Hackett described ZCell as a breakthrough for energy storage. “ZCell breaks many of the rules that apply to legacy batteries, making it ideal for the home market,” he said.

 “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.”

Mr Hackett said ZCell is warranted to deliver its full 10 kWh of stored energy each day for as long as 10 years. He also highlighted the highly recyclable nature of the technology.

“ZCell is primarily made of plastic, aluminium and steel, elements that are easily recycled, while its fluid electrolyte can be reused or repurposed,” he said.

Redflow has previously focused its flow battery technology at the large-scale market, as well as niche applications such as off-grid telecoms towers.

 Up to now, the main perceived limitation of flow batteries has been their low energy and power density compared to lithium-ion (Li-ion) and lead-acid, along with the need for large storage tanks for the liquid electrolytes. This has so far restricted their use to grid-scale and industrial storage projects, mostly in the 100 kW to 10 MW range.

However, Redflow is challenging that perception with the launch of the ZCell, which puts its zinc bromide flow battery technology up against residential Li-ion solutions such as the Tesla Powerwall and Enphase AC Battery.

How much is it?

In terms of pricing, Mr Hackett said he expects the fully installed cost of a ZCell-based storage system would start from $17,500 to $19,500 including GST, with the caveat that the final cost would depend on the installer and the specifics of the job.

While this is high compared to many Li-ion home storage systems, Mr Hackett said the longer lifespan and other benefits of the ZCell would compensate.

“Due to ZCell’s sustainable 10 kWh energy discharge capability, the cost per installed kWh – that is, the purchase cost divided by output capacity in kWh – is highly competitive with other systems on the market, while offering superior technical features,” he said.

He added that the technology is highly scalable, saying it is easy to construct larger systems that use multiple ZCells where more energy is required, such as in larger homes or commercial installations.

Full details of ZCell are available here.

About ZCell

The core of ZCell is a Redflow ZBM2 battery, a zinc bromide flow battery developed by Redflow that is operating at sites worldwide, including Australia, Africa, Asia, America and Europe.

ZCell uses the Redflow ZBM2 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.

ZCell comprises a smart battery, managed and protected by an on-board computer control system, with an integrated ZCell Battery Management System (BMS) which enables on-site battery commissioning, monitoring and control using a smartphone-compatible Wi-Fi interface.

Redflow cites ZCell’s key benefits as follows:

  • large capacity with daily delivery of 10 kWh of energy at a 100 per cent depth of discharge
  • greater safety inherent in ZCell’s flow battery design: mechanical damage does not risk explosion, dangerously high current output from short-circuit or ‘thermal runaway’
  • robust performance in even hot and demanding remote locations without the need for external cooling until an ambient outside temperature of at least 45 degrees Celsius
  • highly recyclable: most components, including plastic, aluminium, steel and ZCell’s electrolyte, are recyclable or reusable.