It's not just the generation; it's also the maintenance. If you own your own rooftop panels and a few go out, it's relatively expensive to bring someone out to replace them...if a mechanically and electrically equivalent replacement exists in 5 years. At utility scale, you're always replacing panels, so you have dedicated staff doing it.
Climbing roofs is in the top 10 deadliest jobs in America. Itβs cheaper to drive out into a field and work on ground level equipment than to climb a height.
Manufacturing defects happen, trees fall, and panels get dusty. They don't merely "sit on a roof." They're anchored, the anchors have spacing and a form factor, and the anchors pierce the roof's waterproofness. They're not electrically equivalent if they output a different voltage range.
