$6,900 per panel adds up to about $3 million per lane-mile.

Typical rural highway costs for new highway are $3 - $9 million per lane-mile, with urban highways costing $5 - $20 million per lane-mile. (per http://www.railstotrails.org/resources/documents/whatwedo/po...)

The estimated 7.6 kwh per day per panel mentioned in the article, if you assume it gets that every day, adds up to 3.344 mwh per lane-mile, which at average US retail electric rates, adds up to $120,000 per lane-mile per year. According to their website, these panels will supposedly be designed to last 21 years, vs. the 7 typical for asphalt roadways. That would bring the lifetime electricity production per lane-mile up to $2.5 million. (not accounting for inflation nor electric price changes over 21 years)

Frankly, I find their 21 year projected life absurd, but then again I live in a state with yearly freeze-thaw cycles shortening the life of roadways. Other than that, it seems like if they could meet their claims, it would be financially feasible to build roads using this stuff.

Do we have a lack of unused space, which isn't crossed every day by tons of heavy cars? If we're going to build these panels, there's no need to build them in distant places that often get damaged, like highways - better put them in unused land near a city to minimize power transportation costs.