If you want a farm, put it on a farm. If you want a solar generator, put it in a clean well-lighted place. All this hybridization (rooftop farming, solar roads etc) is not sound engineering.
We may need to design our buildings to accommodate these kinds of problems, but that doesn't mean they should be dismissed outright -- The potential energy benefits are substantial.
It takes a just a small leap of imagination; we're not talking about magic.
If you take anything away from this discussion, let it be this:
> [Climate change effects] threaten future gains in commodity crop production and put rural livelihoods at risk. Numerous adaptation strategies are available to cope with adverse impacts of climate variability and change on agricultural production. These include altering what is produced, modifying the inputs used for production, adopting new technologies [emphasis mine], and adjusting management strategies. [1]