Toyota Gets Serious About Solar Power

Published 05 July 2019

Hot on the heels of Lightening One, the World's first practical solar powered car, Toyota is getting deeper into solar assisted PHEVs. Unlike plug-in electric cars, solar power has the potential to provide greater range with smaller batteries so could be the breakthrough to free fuel for every car on the roads.

Toyota Motor Corporation in collaboration with NEDO, Sharp Corporation today announced a plan to start public road trials from late July 2019 to assess improvements in the cruising range and fuel efficiency of electrified vehicles equipped with high-efficiency solar batteries.

To enable the trial, Sharp has modularised its world-class, high-efficiency solar battery cells1 (conversion efficiency of 34 per cent-plus2), previously developed for a NEDO-led project3, to create an onboard solar battery panel. Toyota has installed this panel not just on the roof, but also on the bonnet, tailgate and other parts of its Prius Plug-in Hybrid to produce a demonstration car for trials on pubblic roads. By enhancing the efficiency of the solar battery panel and expanding its onboard area, Toyota was able to achieve a rated generation output of around 860W4, a figure around 4.8 times higher compared to the production Prius Plug-in equipped with a solar charging.

In addition to substantially boosting its power generation output, the demo car employs a system that charges the driving battery while the vehicle is parked, as well as when it’s being driven. This development is expected to lead to huge improvements in electric-powered cruising range and fuel efficiency.

Toyota plans to conduct the trials in various driving conditions in Toyota City, Aichi Prefecture, Tokyo and other areas. Data, including the solar battery panel’s power generation and the amount the drive battery is charged, will be gathered and verified, and used in the development of an on-board solar recharging system. Toyota plans to share a selection of trial data results with NEDO and Sharp.

The PV-powered (pohotovoltaic) Vehicle Strategy Committee5, sponsored by NEDO and others, will evaluate the benefits based on improvements in CO2 emissions reductions and convenience, such as the number of times a vehicle needs recharging. The goal is to contribute to the creation of a new solar battery panel market, including the transport sector, and find new solutions for energy and environmental issues.

Performance comparison



Performance items

Prius Plug-in Hybrid


(with solar charging system)

Demo car
Solar battery cell conversion efficiency 22.5% 34%-plus
Rated power generation output 180W approx. 860W
Maximum charge to the driving battery while the vehicle is parked (per day)* BEV**-mode cruising range equivalent to 6.1km BEV-mode cruising range equivalent to 44.5km
Maximum charge and power supply to the drivng and auxiliary battery while the vehicle is being driven (per day)* Supplies power only to auxiliary battery, which powers the car navigation system, etc. BEV-mode cruising range equivalent to 56.3km

* Maximum amount of charge generated by the solar charging system while the vehicle is parked or being driven, converted into travelling distance according to the JC08 Japan test cycle. Calculation based on the Japan Photovoltaic Energy Association Labelling Guidelines (FY2016), taking into account the various losses incurred in onboard systems. Solar radiation amount calculated based on the daily data of the average year between 1990 and 2009 in the Nagoya district (source: NEDO). ** Battery Electric Vehicle.

In April 2016, NEDO, a national research and development organisation in Japan, set up the PV-powered Vehicle Strategy Committee, which comprises members from industry and academia. With the goal of finding solutions to energy and environmental issues in the transport sector, the committee’s research focuses on solar power systems. Sharp and Toyota are active committee members. The committee’s achievements thus far include estimates6 of the potential to achieve an output of 1kW in vehicles, in spite of the limited space available to install power systems, by using a solar battery module with a conversion efficiency of 30 per cent-plus, zero annual recharging (depending on usage patterns) and estimates of the benefits from a reduction in CO2 emissions.

More at:

Toyota NEXO Solar Powered Prius Top


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