An Australian company is working on a production line of 120kWh batteries suitable for commercial and industrial applications.

Business owners are a studious bunch. If there’s a way to shave away costs they’ll spend hours on their homework before they commit. No-one has the luxury to risk a misallocation of capital.

Rooftop solar is a fairly safe investment in the commercial and industrial sectors, with instant bill savings and revenue from large-scale generation certificates. But batteries have been a harder sell. Until the price comes down, they’re seen by most managers as simply too expensive.

One way around that little problem is to make them using cells from batteries in electric vehicles that have reached the end of the road. The power packs in EVs are generally replaced when they have reached about 80% capacity, which means there is plenty of life left in them for sturdy commercial purposes.

Melbourne-based company Relectrify sees so much potential in the C&I storage market it is working on delivering commercial-scale battery and inverter systems in a modular 36kW/120kWh format, using second-life EV batteries.

The initial production run of 20 units, a project worth about $3.3 million, has attracted $1.49 million in funding from the Australian Renewable Energy Agency. The modular design allows for capacity up to 2.4MWh, or 20 units, using single-cable AC connection.

The right fit

Relectrify decided on a 36kW configuration about a year ago as it was developing and piloting a 18kW/60kWh unit and noticed most inquiries were for batteries around the 100kWh-plus mark. A unit about 120kWh will fit most applications in commercial and industrial, it figures, although the company is considering a scaled-down product into the residential sector.

Businesses will benefit from batteries – if they can be made affordable.

“The economic case for battery storage in the range we’re in – from 100kWh to 1-2MWh – typically does not stack up,” says Relectrify partnerships manager product David Sleightholme.

Solar can pay for itself in as little as five years, but it’s far more difficult to justify the case for battery storage. Sleightholme says the Relectrify technology is about 30-40% cheaper than a new solution, an estimate which factors in the company’s battery management inverter technology alongside the second-hand EV battery packs. “It’s a double benefit,” he says.

A lot of inquiries relate to diesel genset augmentation, Sleightholme says, where a battery can complement a genset running intermittently at high efficiency. “The cost savings there, not just in fuel but transporting the fuel to remote sites, is seeing a payback of less than three years,” he says. “That’s a very popular use case we are seeing.”

Price point

Sleightholme describes a sweet spot for lithium-ion below $US300/kWh before it appeals to buyers in the C&I sector. “Whether it’s new or repurposed, that’s where it can really start to see a lot more take-up.”

Two test units are sitting in the Relectrify factory, awaiting AS4777 certification, and Sleightholme can’t say yet where the other 18 will be deployed although he expects some will be headed into service in off-grid systems, to support peak demands at utility level and in EV charging support to avoid high peak demand charges.

The cells come from Nissan Leafs that have been running about the roads of US cities for the past five to seven years. “We like the Nissan Leaf,” he says. “They’re modular, easy to work on and we’ve got good sources of supply.”

Relectrify’s patented software is a combined battery management system and inverter which operates at the cell level.

“In a second-hand pack you will have a varying degree of degradation of capacity of cells; it’s almost unavoidable,” Sleightholme says.

“Some cells might be down at 70% while others could still be at 85%, but you can’t discharge the pack with traditional technology beyond the weakest series-connected cell. We get over that by orchestrating the discharge so that we take more from those cells that have still got good capacity and less from those that are weaker.”

He says the software unlocks an extra 20-30% cycle life in new and repurposed packs. Relectrify estimates a technical life of 3,000 cycles, which works out close to the 10-year warranty on a new battery.

A unit installed in 2019 with American Electric Power in Ohio has put through more than 25MWh over 500 cycles so far.