New Toyota Prius has solar roof for Europe, Japan

TOKYO -- The next-generation Toyota Prius plug-in hybrid gets a little greener with a the rooftop solar panel for recharging the batteries.

Sun power only amplifies the eco-car cred of one of the greenest vehicles. The cells charge the car even when it is parked and can boost fuel efficiency by as much as 10 percent by allowing longer electric-only driving times.

The technology will only be offered in the Japan and European versions of the car -- at least initially.

Koji Toyoshima, chief engineer of the Prius plug-in and its standard Prius hybrid sibling, says Toyota aims to introduce the panels in the U.S.

The problem: The Japan market solar panels are laid on reinforced glass sheeting that doesn’t pass America’s more stringent rollover crash tests.

Toyota doesn’t have the technology to laminate the photovoltaic cells in a resin that won’t shatter dangerously during a rollover, Toyoshima said.

But the company is working on a solution so that it can introduce the solar panels to the U.S. version of the car during its lifecycle. Dubbed the Prius Prime in the U.S., the plug-in arrives Stateside this fall.

“We would like to introduce this, at least in the lifetime of the current model,” Toyoshima said Wednesday at the car’s Japan debut. “It should be possible to do a lot of charging this way in places like California or Arizona.”

In Japan, the plug-in Prius will be called the Prius PHV. Toyota has not announced whether the solar panels will be standard or optioned here.

Various uses

Aside from recharging the batteries during a standstill, the solar panels also supply electricity to accessories such as lamps, power windows and air conditioning when the car is running, Toyota says.

They improve the car’s efficiency by up to 10 percent, Toyoshima said.

Longer-term, the solar panels could see wider applications.

As Toyota whittles down their cost, Toyoshima said the company hopes to introduce the solar-powered technology to other hybrids across the lineup.

The automaker has been developing the solar roof technology for several years, with the Nikkei newspaper reporting the secret development in 2009. 

In 2008, General Motors introduced a Saab 9-X BioHybrid concept car with solar roof panels at the Geneva auto show. 

Philip Nussel contributed to this report.