Automakers are looking to maximize the driving range of their plug-in hybrid and all-electric vehicles, and solar panels are the hottest solution right now — literally. Toyota is well aware of that and has announced a plan to begin public road trials from late July 2019 with Prius PHV (Prius Prime in the U.S.) vehicles equipped with high-efficiency solar batteries.

The trials will take place in Japan and benefit from the support of Sharp Corporation and the country’s New Energy and Industrial Technology Development Organization (NEDO). As part of the program, Sharp will supply onboard solar battery panels using high-efficiency cells.


According to the automaker, the goal is “to assess the effectiveness of improvements in cruising range and fuel efficiency of electrified vehicles equipped with high-efficiency solar batteries.” Toyota installed the Sharp-supplied solar panels on the roof, hood, rear hatch door, and other parts of the Prius PHV to produce a demo car for public road trials.

Compared to the Prius PHV that’s already available with a solar charging roof system, the demo car is superior in every respect. At 860 W, the rated power generation output is 4.8 times bigger and the solar battery cell conversion efficiency exceeds 34 percent (versus 22.5 percent). Most importantly, the demo car uses a system that charges the driving battery both while the car is parked and when on the move.


This development is expected to lead to “considerable improvements in electric-powered cruising range and fuel efficiency.” More specifically, Toyota claims the experimental vehicle’s daily maximum charge to the battery while the vehicle is parked is equivalent to a driving range of 44.5 km, compared to the production car’s 6.1 km.

Things get better when the car is moving, as the daily maximum charge and power supply to the driving and auxiliary battery amounts to a driving range of 56.3 km. The production Prius PHV’s solar charging system only supplies power on the move to the auxiliary battery, which powers the navigation and other systems.

Toyota will conduct the trials under various driving conditions in Toyota City, Tokyo, and other areas in its homeland. The goal is to use resulting data for the development of an onboard solar recharging system.