The subsidies still exist. And while in absolute numbers they seem low, the reduced costs for solar modules still make them worthwhile.

If you don't feed into the grid as a normal person you're right (that's either "Kleinunternehmerregelung" or, if it's obviously not producing any profit, "Liebhaberei"). But if I built a fictive 500kWp solar plant to power my fictive compute center I would have to pay taxes on the self consumed power. Mind I'm a layman, so I might have gotten that wrong, but I'm 80% sure I got it right.