Alastair Sloane: Solar power for greener Leafs

The hatchback Leaf is on sale in Japan, the US and Europe. Photo / Supplied

Nissan is testing a super-green way to recharge its Leaf electric vehicle using solar power, part of a broader drive to improve electricity storage systems.

The hatchback Leaf is on sale in Japan, the US and Europe and will be in New Zealand next year.

Already the carmaker is looking ahead five years, when aging Leaf vehicles may offer alternative business opportunities in using their lithium-ion batteries as a storage place for electricity.

Nissan acknowledges that, once the Leaf catches on, a flood of used batteries could result as the lifespan of a battery is longer than an electric vehicle's.

In the new charging system, electricity is generated through 488 solar cells on the roof of the Nissan headquarters building in Yokohama and stored in battery packs from the Leaf.

Nissan says the stored electricity generated from the solar cells is enough to fully charge 1800 Leaf vehicles a year.

Although interest is growing in renewable energy, such as solar and wind power, a major challenge is the storage of electricity, which remains expensive without a breakthrough in battery technology.

Such interest is likely to keep growing in Japan because of fears about the safety of nuclear power after the March 11 disaster and the damage to the Fukushima nuclear plant.

Toyota and Honda are working on similar projects, such as linking hybrids with solar-equipped homes as part of energy-efficient communities called "smart grids".

Electric vehicles produce no pollution or global-warming gases, but need electricity, whose production mostly relies on polluting coal or gas.

Even after a Leaf is ready to be scrapped, its battery is likely to have 80 per cent of its capacity.

On the plus side, the Leaf with its high-capacity battery can store the equivalent of two days of household electricity use, Nissan said.

"What's important for Nissan is to show solutions through EVs, step by step," said corporate vice President Hideaki Watanabe.

Nissan also hopes to start selling such storage systems for regular homes by the fiscal year starting in April 2012.

It will carry out field tests from December.

- additional reporting AP