While hybrid and electric vehicles are already a common sight in various countries all over the world, the same can't be said about solar-powered vehicles. In fact, there are only a handful of EVs which come with a solar roof as standard or option. Meanwhile, pure solar cars, are often built by university students used during competitions; not for transporting people from one place to another.

Toyota is working on a solar-powered Prius image

Toyota, however, believes that solar power can be incorporated onto hybrids and EVs to maximize efficiency. The Japanese automaker has recently started testing a new solar roof for the Prius PHV (plug-in hybrid), which will supposedly add as much as 44.5 km of range per day. Co-developed with NEDO and Sharp, the new solar battery cells are fitted onto the hood, roof, and other parts of the vehicle and can deliver an additional 860 watts of power.

This isn't the first time Toyota has dealt with solar roofs though. The automaker previous offered a solar roof option for the Prius PHV which only generated 180W and added about 6.1 km of range. The optional solar roof also couldn't charge the batteries while driving, providing power only to the auxiliary battery which powers the car navigation system.

Toyota is working on a solar-powered Prius image

The main difference between the upcoming solar panels being developed is that they are more efficient. Specifically, Toyota claims that the solar cells can convert power at a 34% rate while the previous one only did so at a 22.5% rate. What's more, the new solar cells can even charge the vehicle's batteries while driving, a function that the previous solar roof option couldn't do.

Toyota is working on a solar-powered Prius image

For now, Toyota has not released a timeline as to when we might see the solar roof in production. They do plan to test the vehicle throughout various cities in Japan later this year and share its findings with NEDO and Sharp in order to bring the technology to the market sometime in the future.