I had this idea to rent roofs to install solar panels, building a kind of decentralized power plants. I live in the sunny southern France where summer are starting to become unbearably hot, but at least this comes with a lot of sunpower. There are plenty roofs but sadly we install solar plants in spaces that compete with forest/fertile soil. I am not an energy engineer so that's not a realistic project for me, but are there similar projects around?

There is a similar idea called "community solar" in the US. It allows electric customers to subscribe to the output of solar panels on someone else's roof. This allows a developer to build a solar array on a large commercial building's roof that they rent.

This model has actually taken off in rural China. Salespeople will tell you, "You only need to lend us your roof for 20 to 30 years,and in return, you'll receive a sum of money." Many people in rural China readily agree to this deal. I'm not entirely sure what these solar panel companies get out of the arrangement. Perhaps they sell the generated electricity for a profit, or supply it to factories with high energy demands.