Your first 2 paragraphs have a few holes before they will be adopted as easily as you pretend.

Land for solar installs isn't close to free. My condo HOA won't even consider solar for any homeowner and the HOA won't approve a giant $50k/unit special assessment (we can't even get 40% of homeowners to vote for HOA elections... which are free).

Older buildings not designed for a solar roof aren't too easy to retrofit. My office window overlooks 2 parking lot structures that were recently retrofitted with solar and it took about 6 weeks for a relatively simple install. I'm pretty sure building owners will only install if they get a cut of the solar generation revenue (so the land isn't free) or if they are able to use it to offset tax or utility costs (also not free).

EVs as batteries are neat but... (1) most owners will likely splurge only for the $500 charger station not the complex electronics which allow the EV to charge the house/grid and (2) cars are frequently driven / parked at work during the peak charging time, so they would be unavailable to absorb the majority of the peak solar generation time.

Until there is a solar EV + charging story for dense housing (apartments and condos), I think most users in my area aren't likely to be able to adopt like you seem to think. Community Solar projects seemed nearly non-existent when I searched in 2018-2020.

i thought a balcony solar law just passed in california, might be interesting to see how that goes.

I liked laws like the fcc(?) law years ago that said you could have a satellite dish and an HOA couldn't prevent it. we need more laws like it in favor of common sense/good over HOA nonsense.