Are Solar Roadways the Future? Only At a Very Steep Price
People get excited by solar energy. The Solar Roadways Project, funded on crowdsouring site Indiegogo, claims all the roads in the US could be turned into power generating infrastructure, and has created a working prototype. The estimated 13 trillion kWh of power  generated from these panels could improve road safety, illuminate roads at night to enhance visibility, or melt ice and snow.
While technically feasible, this prospect is economically ridiculous. With 18,000 square miles of paved roads in the US, it would cost roughly $70 quadrillion- yes quadrillion- dollars to implement solar roadways at a cost of $5,500 per kW.  Solar power is simply too expensive to provide base-load power and will remain so without a more momentous fundamental innovation.
This technology could see selective implementation insofar as it provides infrastructure capabilities otherwise impossible or impractical. Dynamically adjusting lane-lines and in-road imbedded signage are potential applications, but those innovations would have to provide benefits sufficient to justify the cost of installation.
There is a reason solar—the purported technology of the future—still only produces 5 out of every 1000 Wh generated in the US over forty years after its invention: it is simply too costly and will likely remain so.
In 2013 the US net electricity generation was about 4 trillion kWh, of which only 21 billion kWh resulted from solar power (0.5%). Moving forward, solar is expected to gain only .05% of share per year.
Though there may be selective applications for which solar roadways make sense, there are not many which make unsubsidized sense. Proponents of roadway solar panels need to put a very high value on road safety, even after capturing the generation of electricity, to justify the cost. The total price tag of $70 quadrillion dollars represents 4,000 times the value of all goods and services produced in the United States (GDP) today. There is no reason to believe we will power our nation through our roadways, nor is there a compelling reason to do so.