The Feasibility of Solar Roads in America

May 21, 2014

There have been multiple videos floating around the internet for the past few years positing the concept of solar roadways in the USA. The idea is that if the US could replace all the concrete on interstate highways with solar panels, these panels could be used to fuel vehicles on the road and nearby energy consumption (rather than fossil fuels) and potentially thaw ice and snow in order to reduce plowing and salting.

My colleagues and I in Nexant's London office chatted about this today and while this is great in concept, why would the US (or any country) spend major investments in re-vamping roads/infrastructure when there is existing idle land and space (e.g. deserts, rooftops, etc.) that could be filled with solar technology first?  Surely, it’s cheaper to build a solar farm + electrical grid tie-ins – in idle land where the solar panels would not be subject to high levels of use/abuse/coverage as found on roads – than to dig up these roads and put the technology in place. 

The limited areas where this might remotely be applicable are enclosed housing complexes where the roads are already maintained privately and cleaned regularly, as well as limited road traffic – possibly extending the lifespan of these solar panels.  For example, a typical American suburban housing complex:

Then, let’s say (an extreme example) all roads are paved with these purpose built solar panels. In terms of the capacity required to this:

  • One panel is around 350W and 1050mm x 1550mm in dimensions (source: Sunpower)
  • A typical, mid-range wafer plant output is 280MW and is enough to produce roughly 800 thousand of these panels at 1.6275 square meters each per year.
  • It would take 123 thousand years for such a wafer plant to produce enough panels to pave the US roads. Or around 470 years for current global PV supply (73GW) to do this.

 

Once the roads are paved, there would be further challenges - maintenance and clarity of these paved roads would be essential for efficiency and therefore costs – the roads would need to be kept spotless and free of dust in order for the panels to work optimally. Furthermore, the optical clarity required for the panel surface does not go hand in hand with toughness/stiffness – unless panels can be designed that do not require cover.

As a wide-scale infrastructure program this one has many challenges to overcome. The best option currently would be to put these panels on every roof (which is being undertaken). It would also be interesting to compare this technology against kinetic energy capturing technology that doesn’t require as much maintenance and is a lot cheaper to produce and implement, especially in walk ways.