I can go to Home Depot or Lowe's, right now, and walk out with a breaker box, conduit, a bag of breakers, a couple hundred pounds of copper, and install my own household 220V/150A electric service. Local codes or the electric company may require an electrician to sign off on my work before I grid tie, but the companies who make the stuff aren't going to refuse to sell to me. Nobody seems to think me killing myself by making mistakes with that would be the fault of Home Depot or the manufacturers, and I'm reasonably confident that is more dangerous than installing a battery box (unless Tesla has built an inherently dangerous device, in which case it won't matter who installs it).

I can also go to the same store and walk out with a roof-sized pile of roofing tiles. No one will stop me from putting on my own roof.

Hell, Tesla sells cars. The single most deadly consumer product, by far, in the world. Admittedly, people have tried to sue them about their autonomous features, but still, cars are really deadly and no one blames manufacturers for those deaths (though, we do, as a nation, impose some safety standards...but, it doesn't stop tens of thousands of deaths every year). Tesla is arguably much better about not killing their customers than some other manufacturers, but they already operate in the most deadly industry (aside from, say, coal or fossil fuels, but the deaths caused by those industries are generally an amorphous statistical blob of health problems rather than distinct deadly events).

My point is: Unless Tesla has built a dangerous product, there's no safety-related reason it should be treated differently than other home improvement items that require the same types of skills to safely install them. Electrical and solar power are well-understood by plenty of non-professionals. I do see the appeal of making it turn-key; they're aiming for average home owners, particularly at the time of construction or roof replacement, when there are already contractors involved and a mortgage to pay for everything. A large-scale solar power installation is expensive, and it makes sense for most people to work it into their mortgage.

But, it's frustrating for me; when I build a house (and I'm kinda shopping for land now in a casual way), I plan to self-fund it and do a lot of the work myself because I enjoy that sort of thing. There won't be a mortgage, and I won't be paying for contractors to do things I can do myself. Electrical work is well within my comfort zone. So, it's frustrating that when I install solar, it'll have to be the somewhat less attractive panels rather than nice-looking tiles.

It's certainly Tesla's right to sell their product however they like. But, I reckon I can complain about it, too.