Will electric cars soon have solar roofs? Toyota and Tesla say yes.

Advanced Panasonic solar modules triple the output of Toyota’s previous solar roof.

CREDIT: Panasonic via NewAtlas.com
CREDIT: Panasonic via NewAtlas.com

Last week, Panasonic announced an advanced solar panel system that will debut on the 2017 model Toyota Prius plug-in hybrid in Japan (the Prius Prime).

It is “the first commercially available, mass-produced passenger car to feature an optional solar charging system,” PV magazine explained.

Panasonic notes that, previously, rooftop solar cells had outputs of only “several tens of watts.” So they were used only for ventilating parked cars and “auxiliary charging” of the standard 12-Volt lead-acid battery.

But improvements in solar efficiency combined with advanced design and “technologies to laminate three-dimensional curved glass” have allowed a high output — some 180 watts, which is more than triple the output of the previous solar roof.

As a result, this battery can charge the lithium-ion powertrain batteries, providing up to an additional 3.7 miles of range on a sunny day. That may not seem like a lot, but it is a large fraction of the daily commute of a great many people, which could result in a big boost for fuel efficiency.

And as solar panels and electric vehicles get cheaper and more efficient, the potential range boost from a solar roof is likely to grow.

The 2017 Prius Prime is a plug-in hybrid with some 25 miles of range available on a fully charged battery before it needs to burn gasoline. Running on gas, it gets 54 miles per gallon (combined city-highway EPA estimate). It’s EPA-estimated electric mileage is 133 mpg-e.

The solar roof option will initially only be offered on Japanese models until Toyota and Panasonic develop an improvement to the reinforced curved glass panels, which would not pass U.S. rollover standards.

Finally, Tesla CEO Elon Musk tweeted in November that he wanted a solar roof option for the Model 3, Tesla’s affordable long-range electric car that had record pre-sales:

Since Panasonic has famously partnered with Tesla on its Gigafactory — and since Tesla has already developed an all-glass roof for its Model S that gets a five star rating in rollover testing — advanced solar-roof technology may make it into U.S. showrooms quite sooner.