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Aquion Salt Water Batteries
Salt water batteries? It sounds kind of crazy, doesn't it? But Aquion Energy, a US-based manufacturer, has created a special kind of battery technology that they call 'Aqueous Hybrid Ion (AHI)'. Their S30 battery stack is pictured.
Salt water batteries are inherently safe due to their chemistry, and they boast a 100% depth-of-discharge capability, with a life cycle of around 3,000 cycles.
This isn't as much as lithium-ion batteries can boast – around 5,000-6,000 cycles with an 80% depth-of-discharge – but the technology behind Aquion batteries gives them a number of advantages over their lithium-ion counterparts.
For one, saltwater batteries are non-flammable and non-explosive, require no maintenance, and are built entirely from non-toxic materials. In fact, they are the only batteries in the world to achieve 'Cradle to Cradle' certification.
Aquion's S30 batteries are optimized for long-duration daily cycling, which means 4 to 20+ hour charge and discharge cycles, which is ideal for solar. They are abuse tolerant and do not degrade from partial state of charge cycling, which is typical of solar applications.
They can also have individual modules replaced/expanded without any detriment to the rest of the battery setup. It is much harder to scale lithium-ion battery banks compared to the Aquion Energy banks.
The main drawbacks are the slightly lower life cycle compared to lithium-ion and a 5-year warranty (as opposed to Tesla's 10-year warranty for the Powerwall). They also have a low power output per stack – about 0.68kW of steady power – which means that you need to buy at least 5 stacks (0.68kW x 5 = 3.4 kW steady power) to get enough power output to power an average Aussie home.
The low power capability means that you have to be careful when designing your system. High power loads can overwhelm these batteries and trip the battery inverter making for an unreliable system. A clued up system designer is especially important when implementing these batteries to avoid this issue.
Aquion batteries are suitable for both hybrid and off-grid solar setups.
How much will an Aquion battery + solar setup cost?
The Aquion Aspen 48S, a 2.5 kWh battery stack, costs roughly $2,200. A high quality 5kW solar system costs about $8,000.
So, 10kWh of Aquion energy storage (a good amount for the average Aussie home) with a 5kW solar system will set you back roughly $18,000.
Combining that price with its modular scaleability, the Aquion battery represents a cost-competitive battery storage option compared to lithium-ion. However, the company's salt water technology is new, and with all new technologies there are risks.
Speaking of risks, on March 8, 2017 Aquion filed a voluntary petition under Chapter 11 of the United States Bankruptcy Code. Aquion Energy emerged from Chapter 11 bankruptcy status with new owners at the helm in July 2017.
As for availability, Aquion has established dealers and distributors in the Australian market.