The problem is that if the rich areas start being able to mostly go off grid, the franchise provider is now screwed having to provide to the high cost areas while still also serving the low cost areas, but receiving much smaller revenue due to the roof top solar/batteries cutting usage of the grid.
If we consider subsidizing power to the poor a valuable social service, then we should state that bluntly and not beat around the bush with regulations technically disconnected from that goal. "Sure, you can go off grid, but you'll still need to pay a $25 a month tax so your neighbors can pay less". Simple as that.
Realistically, though, people already have ways around these regulations. Simplest case, AFAIK nowhere has outright banned solar installations, only either going off-grid or a grid-tie system. A mechanical cutover switch, rather than a grid-tie, satisfies both of those conditions, and counts as pretty common hardware for whole-house generator backup systems. Of course, if you think people resent their electric bills now, wait until they literally have to pay $25 a month, every month, for 0KWH. IMO, you'd find that more palatable as a feel-good tax than as a "fee" paid to companies only slightly less hated than cable and cellular carriers.
Personally, though (and I accept that you may legitimately disagree with me on this), I don't see it as necessarily beneficial to force the poor to pay $100-200 a month just because my standard of living requires electricity. If someone can reasonably live without power and can find a better use for a grand or two per year, hey, more power (no pun intended) to 'em!