I think it's worth taking note of the approach Tesla took in introducing EV's to the market. Start at the high end, use these profits to subsidize the R&D and capital expenditures necessary to work down market. In this context, Tesla solar roof is a best an early model Model S. It is a product that is a work in progress. Available to a few, relatively wealthy consumers, who also happen to be tastemakers. I would expect to see solar roofs move down market over the next decade, just as EVs have this past decade.
I think this is what most people expect... but what I'm suggesting here is that the Model S approach worked really well because there were no other examples of EVs on the market in general.
Tesla solar roof is like a Fiskar Karma- it's just an expensive alternative to a system that already works. There are already solar panels on roofs. And there are already battery backups. Tesla roofs aren't adding anything except aesthetics (and that they force you to buy one if you want a Powerwall, a much superior product IMO).
Edit: (lots of these for me, lol) and much like solar roadways, their roof panels will never be as efficient as straight solar panels due to coloring and texture. Again, this is less of an issue than cost, but I did want to note it. They are limited by physics in this aspect (in the same vein, lithium battery capacity is showing strong signs of reaching maximum density).
I think there is still a market for Tesla-Roof like systems, but the whole idea isn't very scalable. If solar generation is indeed the best way to make energy, then we are going to see more solar farms being built with proper panel angles (or solar tracking) and more easily cleaned. Large scale solar systems producing energy will make utilities less incentivized to have strong net metering payments because they will already be getting energy generation when the sun is out. Right now it is a small population of houses but that power will be less valuable for grid management. It may be beneficial to only have a Powerwall for price arbitrage and let the utilities generate the solar plant (this I think is optimal, but I'm not going to try to crystal ball this one). These are the things that I think will limit the ability for Tesla to scale the same way they are doing with cars. The hurdles on the grid are not the same as the hurdles in automotive.
I have no doubt that Tesla has great minds on this. I do have some doubt that investors do.
First, let me say that I do appreciate you have expertise in this area and your contributions to the discussion. I think nearly all of what you’ve said in this thread is true (as of today). But, as you yourself noted, there were a ton of supposedly super smart auto engineers at the big legacy auto companies and auto analysts on Wall Street that scoffed at Tesla's EV prospects. It can be detrimental being in an entrenched culture that’s always done it a certain way.
For example, you are correct that as of today, it does not make any financial success to install a Tesla solar roof as opposed to conventional panels on an existing roof. However, the goal of solar roof is to reach economies of scale, like they did in autos, such that the cost of installing a new solar roof is the same or comparable to a new asphalt shingle roof. At that point it's game over. Why would anyone install a roof that doesn’t produce “free” electricity for the same price as a conventional roof. Installing a conventional roof and then adding solar panels would look worse and cost more. Added benefits include the solar roof having a lifetime warranty against damage. The solar roof is far more resilient against wind, hail, and fire. No small thing in our era of climate change. I could even see insurance companies offering discounts on home insurance.
You’ve also said that renewables plus batteries aren’t a utility level solution. However, in places like Hawaii, California, and Australia (Hornsdale), we are seeing massive utility scale battery installations, where Tesla Mega Packs are coupled with wind/solar farms to replace NG gas peaker plants. I understand base load is different than peakers, but I wouldn’t bet against Elon/Tesla solving that as well. Transmission is solvable, it really just requires political will and capital, there’s no new technology needed. Placing wind and solar farms adjacent to existing/former power plants and placing Mega Packs at the former power plant locations is another potential solution to transmission. I also understand that sometimes the sun doesn’t shine and wind doesn’t blow. This can be solved by overbuilding wind and solar capacity. If we 2X capacity (shooting from hip) then we’d only need the sun to shine and wind to blow half the time and utility battery storage and Tesla software to smooth out the supply vs demand equation.
I accept that you can (and likely will :) take what I’ve written above and tell me half a dozen ways it won’t or can’t work. My answer would simply be that Elon thinks it can be done and I wouldn’t bet against a guy who figured out how to reuse rockets by landing them vertically. NASA, Boeing, and Lockheed all scoffed at the notion of a private company doing manned space flights, resupply missions to the space station, and the idea of reusable rockets. Elon ate their lunch and did it all at a fraction of previous costs. In comparison, I don’t see how utility scale renewable plus storage is some unsolvable conundrum.