Two years ago, YouTube phenomenon "Solar Freakin’ Roadways" garnered 21 million views as part of an Indiegogo campaign, leading 50,000 backers to pledge a total of more than $2 million to help a burgeoning startup to develop road-integrated photovoltaics.

Despite skepticism from many experts, parent company Solar Roadways has persevered, winning a two-year, $750,000 contract from the U.S. Department of Transportation last November to pursue its vision.

But what if the solar industry is already realizing Solar Roadways’ dream, without the added engineering challenges and costs of designing load-bearing structures which meet regulatory requirements?


About 25.6 gigawatts of solar photovoltaics had been deployed across America through the end of 2015. GTM Research and the Solar Energy Industries Association forecast a further 16 gigawatts of deployment by year’s end, bringing cumulative photovoltaic capacity to 41.6 gigawatts of installed capacity.

Assuming an average panel rating of 150 watts/m2, this equates to 280 million square meters of photovoltaics being deployed across the country by the end of 2016 (41.6 billion watts / 150 watts/m2 = 280 million m2).

And although 150 watts/m2 is on the low side of current photovoltaic offerings, it’s probably in the mid-range of the American PV fleet average, as panel efficiencies have steadily improved in recent years.

The United States has almost 48,000 miles of interstate highways, with a standard lane width of 12 feet. Applying the necessary unit conversions, it would coincidentally take about 280 million square meters of solar panels to cover one lane (in one direction) of every interstate highway with photovoltaics.

That’s quite the happy coincidence -- a synchronicity, to borrow a term from Jungian psychology.

...And railways

Casting our contextual nets further, the U.S. freight rail network is the largest in the world, with a length of about 140,000 miles (225,000 kilometers). Amtrak’s passenger rail network adds another 20,000 miles (32,000 kilometers), with its inclusion or exclusion explaining the discrepancy in online estimates for the size of the country’s rail network.

The distance between U.S. railway tracks -- or “track gauge” -- is 4 feet and 8.5 inches, or 1.4351 meters. (Outside North America, so-called standard gauge has been defined in metric terms as exactly 1.435 meters.)

Laying photovoltaics between the rails of the American freight rail network would then require about 320 million m2 of solar panels. An additional 45 million m2 of panels would be required in order to add in the passenger rail network. While that’s out of reach for the 2016 presidential elections, both should be achievable by the 2018 mid-term campaigns.

On-ramp to the “solar singularity”

Returning to America’s highways, even after pushing our timelines out to allow for calculation uncertainties, we can still confidently claim that by the time the 45th U.S. president is sworn in on January 20, 2017, America will have deployed enough solar to have covered one lane on its entire interstate highway network in photovoltaics.

In viral video terms, that’s one lane of Solar Freakin’ Highways.

And by Inauguration Day 2021, GTM Research’s projections further suggest the United States will have deployed enough additional solar to cover one lane in each direction. (Even assuming a probably-optimistic average panel output of 195 watts/m2, the roughly 55 gigawatts of projected solar deployment from 2017 through 2020 will involve an additional 280 million m2 of photovoltaics.)

In grid edge community terms, while the solar singularity needs more time, the solar synchronicity will arrive imminently.

Matthew Klippenstein (@EclecticLip) is a professional engineer and co-host of the EV-centric CleanTech Talk podcast. He has chronicled the Canadian electric-vehicle market for Green Car Reports since 2013. In his role with a leading renewable energy consultancy, he evaluates the wind energy potential of prospective wind farms. 

Interested in how the U.S. solar market will continue to evolve? Join leaders from across the solar value chain at GTM's Solar Summit taking place May 11-12, 2016 in Scottsdale, Ariz. Register here.