depends where you put them. Ground mount also has the disadvantage of dirt getting on the panels - which reduces yield pretty fast. The higher you are up the cleaner the panels stay. I think ground mount solar farms on bare undisturbed land should be outlawed as long not every parking lot has solar carport on them. Digging up natural land to place solar panel is not very sustainable.Maybe I'm an optimist, but it was interesting to see they were getting gains at only 7cm. With the prices we are seeing for the et solar 410w panels, I thinks it's still worth it for 5-10%.
use already disturbed land - don't use more land.