Apparently, the Netherlands has run out of rooftops, as it is currently installing solar panels in bike paths. The cost for a pilot project is 3 million euros (about $3.7 million) for 70 meters (230 feet) of bike path. That’s equal to $85 million per mile.
The article doesn’t say, but the Antiplanner estimates from the photos that the path is four meters wide. That means it is costing more than $13,200 per square meter or about $1,225 per square foot.