Lots and lots of land. Now, we've got to manufacture a whole mess of solar cells. Too bad, progress is progress. Let's not forget that semi-scarce materials have to be mined.
More demand means new supplies have to be found.
Now we've got to do the same thing with electronic equipment to convert the direct current of the cells to alternating current. They're big, ugly, noisy, and difficult to work on. Of course, we have to dispose of the batteries when they wear out. Since this power station is probably in a hot desert, we'll need major air conditioning to cool the electronics. Hope this station will generate enough juice to power the electronics, air conditioners, and still have some left over to distribute.