- Magnitude higher number of interconnections which impacts reliability and efficiency
- Uniform roof tile style
- Requires entire roof rebuild which is always more expensive than retrofit of panels on top
- Complex installation resulting in less installers available overall for the market
- Crossing of trades between roofing & electrical
A slightly better solution would have been to make the big traditional solar panels your actual roof panels but really retrofitting them on top of panels solves most of those issues above.
The market pitch is different tho, they are aimed at providing less effective solar for places where you have a hard need to keep the old look, old churches, monumental buildings and such.
The market shrank because standard panels and their mounting techniques got more aesthetically pleasing and cheaper.
On the other hand, Tesla's solar shingles are tiny compared to panels, more in the shape of actual shingle strips, means tons of connectors, wiring losses, dangerous shorts (these things carry 10s of amps) etc. and probably a nightmare to troubleshoot.
I would not get these for any reason other than aesthetics.
IMHO a pergola or carport is going to be better. You lose solar efficiency but gain the benefit of something that provides shade. Especially as solar panels have become an economical roofing option if you don't care about perfect waterproofing.
Multiple tiles also need to be connected in series to get reasonable efficiency, so you get plenty of failure points where one bad connection can cause a significant part of your solar roof to become useless. And you won't be able to easily fix it.
You can obviously fix all these issues, but it makes tiles too expensive.
Essentially, you are adding another zero to the cost to have hidden solar. A 20k solar install becomes a 200k+ solar roof install.
Even if the final result is great, the economics shrink the possible customer base. Basic solar has gotten so cheap that people aren't worrying if the investment increases the value of the house itself. But very few people are willing to pay 10x for a thing that will never pay itself back in energy or home value. It's like putting a pool in your house - a few buyers will want it, but a lot will run from it because they don't know what to do with it.
So as a result, the target market ends up being super rich dudes in gated communities - the same kind of people buying custom 100k hifi systems and home cinema rooms. It becomes an upsell for people with unlimited budgets.
It's just not a mass market product when the competition is 10x cheaper and dropping daily.