Greece has a total highway length of about 2.500km, making it the biggest one in Southeastern Europe and one of the most advanced in Europe [https://en.wikipedia.org/wiki/Highways_in_Greece]. It is also blessed with a lot of sunlight and a high solar irradiance. [https://en.wikipedia.org/wiki/Solar_power_in_Greece]
The above map shows Greece’s photovoltaic power potential. This estimates, how many kWh of electricity can be produced from a 1 kWp free-standing c-Si modules, optimally inclined towards the Equator. Let’s use an average annual sum of 1,400kWh/year per square meter.
So, why not mount an 1 square meter solar panel on top of every highway light in Greece?
Doing the Math
A good rule of thumb is that street lights should be placed apart three times their height. So, for the sake of simplicity, let’s assume the average light height is 10 meters. This means that street lights should be places 30 meters apart. By making a quick division, this gives us about 83,300 lights on each side of the road; times 4 (for each direction) and we get a total amount of 333,200 street lights. Now, multiply that with 1,400kWh and we get a total of 446,480MWh/year. Lastly, getting the power output of this distributed power plant is easy. Given that the year has, 8760 hours, we get a total installed power output of 53.251MW.
This is far greater than any other solar power plant currently operational in Greece. It is also a “distributed” plant, meaning that there is no single point of failure. Furthermore, given the nature of the highways (they span all over Greece), the cost for transporting the energy is greatly reduced. In conclusion, having your highways, and why not the other major roads, also act as a power plant is a non-disruptive way of producing energy. The benefits far outweigh the additional costs and it can lead to a much cleaner and sustainable future.