Massive fields of solar panels are centralized in their infrastructure - they have a single outlet onto the electrical grid, they are all maintained and administered in the same way, etc. - so they fit well into a centralized social power structure.

Same as farms for the past 5,000 years.

Decentralization would mean something like rooftop solar and household batteries. But even then the manufacturers could hold centralized power; you would have to be able to mix-and-match between manufacturers in usage and repair.