Why are they illegal? What is your source?

Homeowners can’t put solar panels on their roof to use the produced electricity?

Nope, because of laws written by energy company lobbyists for the "safety" of consumers, so if you're mixing grid and solar on the same site (even if completely isolated circuits) you have to get all kinds of certifications and permits for inverters and breakers installed by certified technicians that make it cost prohibitive.

Also, many HOAs and local governments place ridiculous restrictions of their own right

I posted more on the other branch of this thread. But cost prohibitive is about all I can find about this and not illegal. Which for some people might be the same result of course.

As I understand it. They banned solar inverters as well as severely tariffing the panels. In some places it's also illegal not to get your electricity from the grid.

From what I can find online that doesn’t seem true. There are import restrictions and various other restrictions, but they don’t seem to be illegal.

Then again I don’t live in Texas let alone the US so i might not know where to look and I don’t care enough to truly find out.

I was just surprised that they were supposedly illegal. Which seems untrue.