I’m not sure if this Solar Roadways concept is insane or brilliant, but I think my gut reaction is that this is generally far fetched – at least on the scale these visionaries are thinking about. Having noted that, I also think it might be useful for some specific roadway signage applications in the short run. Regardless of my thoughts, however, the SR idea apparently made enough sense to the U.S. Department of Transportation to get the agency to tentatively agree to give a $100,000 SBIR Phase I grant to the Idaho-based SR group to build a prototype.

Here is SR’s idea: Create full roads out of structurally-engineered solar panels. Yes, they would be driven on! These panels would provide a road surface, and collect and store energy to a LED transportation communications system built into some of the panels. Excess power would be pushed into the grid for residential and commercial use.

SR proposes making three-layered panels:

  • The surface layer: Traction-designed, weatherproof and translucent. High-strength glass?
  • The electronics layer: Primarily the PV layer, but with LEDs for “painting” and signage built into the road surface, and ultracapacitors for energy storage.
  • The base plate layer: This layer insulates the upper layers, and distributes power and data signals.

SR says that it expects that each panel could produce 7600 Wh and 3.344MWhr per lane, per mile of electricity based on 15% efficiency and four hours of sunlight per day (for more details, see their Numbers page).

The issue of glass strength isn’t really addressed head on by SR. An FAQ on SR’s website has some discussion about traction issues, and mentions that presentations have been made at an International Workshop on Scientific Challenges for New Functionalities in Glass workshop and to Penn State’s Materials Research Institute, but fails to making a convincing case about whether current glass materials are up to the task that the SR concept poses.

One of SR’s weaker arguments is that the group envisions these panels as needing little maintenance (“Hey – we can use self-cleaning glass technology!”) and eliminating snow plowing (“Hey – they can heat themselves. No more snow/ice removal and no more school/business closings due to inclement weather!). For a company based in Idaho, they seem oblivious to the notion that state DOTs spend a lot of time and money on snow and ice removal despite (and because of) the fact that current roadways act already as heat sinks. SR panels would also be vulnerable to snow drifting.

Here is Scott Brusaw, one of SR’s key figures, discussion the proposition: