Have you ever stepped out onto the street barefoot in summer and had your feet scalded? The road is hot! Roads aren't very wide, but they are very long, and the fact that the sun's beating down on all that developed surface area every day gave me an idea -- why not build a very tall canopy over the road, open on the sides and supported at intervals by posts that would double as street lamps, and cover the top with solar panels? The canopy could be shaped to maximize efficiency for the panels on it, depending on the direction of the road. Since roads are land that's already been developed, there's no extra environmental impact of building a new power plant on agricultural or wild land. The access provided by the roads would make it relatively easy to install and maintain it, and it would provide another benefit -- shading the road during the hottest part of the day. Maybe it would be cool enough to occasionally turn off your air conditioner while driving, saving gas, money, and further preventing pollution, and the extra shade might make the city itself a little cooler and more livable at ground level. It probably wouldn't work on all roads, but with the huge amount of road surface area in any city surely there would be enough eligible road to power the city. Additionally, such structures could be installed over parking lots or other public spaces.
Is that a ridiculous idea?