In general yes but due to both taxes/regulations and real issues with the grid it is "easier" to just consume what your produce vs producing and selling to the grid. And since space is limited on most peoples property if you live an urban setting then roof might be the only place to put it. If you got plenty of space though roof is a worse place than the ground from almost every point of view.

Every PV system on a roof means producing and consuming energy directly.

In Germany we already have large distance energy transfer problems.

And PV is so cheap now + battery, you get independence / real freedom out of the box.

If you have valuable space on the ground and want to remove the utilization of it, sure but I prefer it on the roof were it doesn't do that.

But yes next to autobahns or other smart locations yes put it on the ground.

But when I invest in myself I will not sponsor pv somewhere else