This is what some people have been saying for over a decade.
I've worked in many schools and lots of them get snakeoil salesmen for everything from solar power to "power conditioners" (that "save money on running your flourescent lights!") and all sorts. The ones who have been approached for solar panels on roofs (and they have a LOT of roof space) have either refused it, or regretted it later.
One school I know has panels that barely pull in enough to run one of their on-site servers. They have it "because it looks good", green credentials and all that.
But while you are subsidising something, it usually means it's not a viable business model on its own. Look at all the other green energy methods and they all have huge subsidies. We are burning cash instead of coal to reduce carbon emissions, not generate power efficiently.
All the large solar panels that I price up for my area are useless and barely pay for themselves within their lifetime. You can't sell that. Not once you include problems with ownership of the roof (is it part of the mortgaged property or not), electrical connection, and so forth.
Sure, I can run a few lightbulbs in a shed from a panel on its roof, for a hundred GBP or so. But apart from that, it's not anywhere near as good as people make out. Even if the technology exists, the commercialised versions on small home scales aren't viable in much of the world.
I once priced up a HUGE wind turbine sold for home use in my local DIY store. If a force-nine gale blew for 5 years straight and it never needed installation, planning permission, maintenance or anything doing to it, it might just pay for its purchase cost before the warranty expired.
People loved it, everyone looked at it, a few talked about buying it. Nobody did. They took it away after a few years and I asked - they sold basically zero of them from that store.
Solar is the same. While subsidies and selling crappy, unreliable, variable, low-voltage, low-power back to the grid exist, they are okay. Just okay. As soon as those things disappear, it's game over. But, hey, "the next generation" will be more efficient, cheaper, etc. etc. etc. as always. Just replace everything you buy every few years.
I'm sure it's possible to live off the grid, to have solar power be "the thing" that you live from. But it's far from easy, not cheap, requires a lot of work, investment and surface area, and involves a lot of sacrifices.
Solar roofs? Only selling to people who happen to be changing the entire roof (which they likely want done quite quickly and cheaply), rather than selling to everyone who already HAS a roof? That just seems suicidal. Solar panels are identical, modular, and can be put onto anything. A solar roof would have to be bespoke, supplied quickly, and be inside the cost of a roof plus a handful of panels. And you can spread the cost of the roof and panels quite simply by buying modules as you can afford them. An all-or-nothing roof would only be put on new-builds, and likely would have to be designed for.