The production of enough solar electricity to cover all needs of our modern society, requires large areas of land that are not always available. One solution is to use houses top roofs and building facades. A more recent alternative is to use roads. This idea is backed by the observation that a given road section is occupied by vehicles only 10% of the time. This means that 90% of the time, roads are unexploited and hence exposed to the sun.

The Solar Roadways Project

The idea of turning roads and parking lots into solar farms has been adopted by Solar Roadways (see Video 1). This US project from Idaho has been funded in 2014 through an Indiegogo campaign. The least we can say is that Solar Roadways attracted a lot of attention. It raised 220% of the amount requested reaching a total of $2,273,553 USD! The proposed solution relies on hexagonal tiles that collect electricity through photovoltaic cells. Solar Roadways tiles also include LEDs. Thus, they allow for displaying information directly on the roads. Moreover, they contribute more actively to safety, since they embed a system to melt ice and snow in winter. The first pilot installation has been made public on September 2016.

Criticism of Photovoltaic Roads

Although available for sale, the technology for solar roads is still at its infancy. Some folks even believe that it’s a bad idea (see Video 4) and favor instead solar panels on rooftops that are currently 6 to 8 times better. Solar panels for rooftops are about 3 to 4 times cheaper than Wattways. The other issue is the amount of generated electricity. A comparison of the yearly electricity production of the dutch solar bike road and three houses with photovoltaic rooftops shows that we get twice as much electricity per square meter from a solar rooftop than from a solar road.

Sure we should not expect a major improvement of solar roads productivity. They quickly get dirty, and they cannot be tilted to maximize the amount of received light. Besides, photovoltaic roads have to withstand the weight of cars and tracks, as well as the scraping of dust and wheels. Photovoltaic roads will then obviously stay more expensive to produce than solar panels for rooftops, although the difference in price is likely to drop. By discarding the idea of solar roads, don’t we throw the baby out with the bathwater? Shouldn’t we have both solar rooftops and solar roads? Shouldn’t we consider other potential benefits of solar roads such as information display, and snow melting as introduced by the Solar Roadways project?