Not really, there is plenty of land which is not suitable for other things. The solar power to cover all the worlds need could fit in a large desert. And it's

Not really, there is plenty of land which is not suitable for other things. The solar power to cover all the worlds need could fit in a large desert. And it's much cheaper and easier to install a ton of panels at once, then one and one on rooftops with varying size and design. It' also easier and cheaper to keep them clean. But one does not rule out the other. The world should probably invest massively in both kinds of solar, since solar at rooftops with battery storage can help reduce the burden on the grid (especially when people start to need electricity to charge cars).