How used EV batteries can be recycled for domestic solar use

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The first-generation Nissan Leaf, of which there are close to 10,000 on New Zealand roads, often cops a bad rap for the restrictive range of its weedy 24kWh battery.

However, said battery is increasingly adopting a second life as a viable, more affordable alternative to anyone in need of solar energy storage and offering an insight into the life of used batteries from used and new EVs.

Where a sexy new Tesla Powerwall 15kWh battery will cost nearly $12,000, a used Leaf battery module can cost half as much, yet still, possess enough home serviceability to trump the Tesla by providing increased energy storage.

Often the used Leaf battery is capable of storing 19kWh of energy, enough to keep the average household in spark for two nights or more.

Most Leaf batteries become unsuitable for the car when their efficiency drops to 80 per cent, something that normally happens after about seven years on the road.

The early Leaf model has a workable range of about 130km when new, but the range drops steadily with use, especially if ultra-fast chargers are used.

Even when the car is new, Nissan recommends only charging the battery to 80 per cent to prolong its health, leading to a range of just 100km. When that 80 per cent charge range drops to just 80km, the viability of the battery for EV use becomes questionable.

However, solar energy storage, where electricity flows are tidal rather than the huge surges needed to propel a 1500kg EV, is a lot kinder to battery health. A used Leaf battery can, therefore, provide decades of service as home storage for solar energy.

One New Zealander discovered this, quite literally, by accident. When a Nissan Leaf owned by a Raglan man was a collision and could no longer be used on the road, he pulled the battery out and used it to replace the array of lead-acid batteries that used to store the energy from his home’s solar panels. Such was the increase in the amount of solar energy he could store, that he was immediately able to take his home off the national grid.

Over in California, where solar energy now provides 20 per cent of the state’s needs, used Leaf batteries have become increasingly sought after.

Large solar installations, such as those serving wineries and breweries, will stack the used Leaf battery modules in shipping containers to store the energy generated by their acres of panels, and some of these “container” battery arrays can now store 300kWh of energy.

In a state with such a high level of solar generation, the affordable energy storage solution provided by partially depleted Leaf batteries is as welcome as summer rain. Not only does it negate any need to break down the batteries to recycle their individual components after their use in the cars, it also helps stabilise the electricity grid and peak time prices.

California was in danger of over-generation in afternoons, while night-time electricity prices were skyrocketing.

The trend towards home energy storage, as encouraged by the availability of used

Nissan Leaf batteries as well as more expensive alternatives, has eased both problems to the point where they no longer require state intervention.

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