A number of automakers and suppliers have played around with the idea of using solar panels to charge electric vehicles. This makes a lot of sense as cars spend a lot of time outside, where they could be charging underneath the sun.

Nissan seems to agree, as they’ll use the Japan Mobility Show to introduce a Sakura EV equipped with an Ao-Solar Extender. The device takes the form of a roof-mounted box with a 300W solar panel sitting neatly on top.

However, the real coup de grâce is an expandable section that deploys from the front to reveal an additional 200W panel when parked.

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This means you could easily deploy the panel when you arrive at the office, and then retract it when you’re ready to go home.

While the Ao-Solar Extender’s usefulness would vary by location and weather conditions, the company estimates that owners could capture enough solar power to drive 1,864 miles (3,000 km) annually.

That doesn’t sound like much, but the average American drives less than 40 miles (64 km) per day, so you’re looking at more than a month and a half of range from the sun alone.

Nissan said they studied the usage patterns of Sakura drivers and found that many customers only travel short distances. For some, the Ao-Solar Extender would be able to “virtually eliminate the need for external charging.”

That’s pretty nifty, and Nissan noted that when the panel is extended, it effectively acts as a sunshade. This helps to keep the Sakura’s interior cool, which reduces power consumption by the air conditioner when you return.

And in true Japanese fashion, Nissan has given it one more layer of usefulness, allowing the Ao-Solar Extender to function as a backup power source during emergencies.