Yes, the cost of GENERATING electricity will undoubtedly be cheaper at the industrial scale level than on your rooftop.

But that generated electricity is likely to be a region very far from your (or someone else's) consumption - needing a lot of money to lay transmission and distribution lines to the end consumer.

Co-locating with consumption makes the difference in total costs far closer.

Very location dependent, but please don't dismiss offhand without considering the very real transmission costs.