[namibj]

Also you can easily put solar over e.g. car parks, in which case you don't even need a proper roof if you funnel water from the panels towards the gutters without splashing the users walking to the cars. The cost should be within 30% of the panel price itself for a decent-size parking lot, less if you can get economies of scale through standardized modules that are placed next to each other to form rows for the cars.

A bonus would be that the cars don't heat up as much/get packed with snow.

And the land isn't wasted, because there is no reason not to have a roof over a paved parking lot other than the fact that a roof costs money to build and maintain, which isn't an issue with solar. You already can't use the land for plants/nature, so you might as well put your solar there instead of some open field/grassland that can be used for something else.

[anoncake]

> You already can't use the land for plants/nature

You can put plants on rooftops, we just don't.

[kalium-xyz]

You ever see those projects where they generate biofuel from algae growing ontop / against building using special build tanks? Its really cool.

[bubblewrap]

Cool, but also energy efficient?

[anoncake]

It certainly beats bare roofs. AFAIK photosynthesis is still more efficient than photovoltaic, too. In any case, it's easier to store biofuel than electricity.