I don't know about wherever applegrove lives, but schools and companies here in Silicon Valley have been doing this with their covered parking lots ("car parks" is Brit-speak, BTW) and buildings for a decade or two. The two issues that limit this here is that many parking lots are not covered, so it's not a simple as, "Slap solar panels on it and you're done." As for buildings, many older buildings roofs were designed before HVAC became common and are fully- or over-loaded with the addition of HVAC on the rooves. My previous employer's roof was so overloaded that it had a partial roof collapse.
But if the Enviros stop hijacking farmland for solar farms, that would be good.
