The requirements to work as a self-employed electrician (AKA electrical contractor) differ greatly fro place to place.
Some states (like mine, California) have statewide licensing requirements that require 4 years of full-time experience in the trade plus passing fairly tough exams on contracting law/business practices and on the technical aspects of the trade. It is illegal to do contract electrical work (except very small jobs, i.s., less than $500) without a state license, and the law is actively enforced.
In other states, including many of the southern states, there are no or only perfunctory statewide or municipal licensing requirements. In some areas, it's just a revenue stream--you pay a fee, and get an electricians license. In other areas, you have to have personal connections to get a local license. I've heard that the small to medium size towns in Colorado are like this.
In California, to get the experience, you either do a union apprenticeship or (more commonly) work for a licensed electrician for 4 years. Ideally this is an apprentice-type experience: first you're a grunt/helper, and are taught on the job how to do progessively more complex tasks, and allowed to do them with less direct supervision.
In contrast, often in tract house building, it's a sink-or-swim sutuation where a new guy is given little instruction and told to go to work. And the quality of the work shows it.
In terms of being able to make a living, I think that the areas with the strictest licensing programs are the best place to make a living wage and do work you can feel good about.
In the areas with no licensing or enforcement (and with no or poor inspections by governement building departments), any goober can call themselves an electrician, turn out poor to dangerous work--and many do.
These hacks aren't businessmen either, so they'll do work at a depressed rate, not even covering their expenses and a decent wage, much less producing a profit. They don't stay in business long, but there's a steady supply of them, so it's difficult for a good tradesman to make a go of it.
As far as RE/PV solar, I've taken a solar electric installer's class sponsored by the California Energy Commission. The PV stuff is different enough from normal grid power installations that I feel you had better take some specialized training or you could get hurt real easy.
As far as a need for PV/RE especialist electricians, I think it'd be difficult to make a living at it. The PV technology is so expensive that even an on-grid PV system has to be heavily subsidized to be affordable. California has had a program to subsidize on-grid PV and so there was some work to be had, but that program ended and so there's little call for PV (except among the dyed-in-the-wool envoronmentalist community, who are usually cash poor, and the very wealthy "wanna-be-green" community.)
Check out Home Power magazine (available on the web as well as a monthly paper mag), and also Real Goods Trading Co., a RE technology retailer in Hopland, Ca. The Real Goods people have a non-profit institute that offers RE/PV and sustainable living classes. They're really good but not cheap.
One way to approach a career change would be to keep a part-time teaching job and work part time as an electrician until you have the knowledge, experience, and business sense to go full time with your own business. Or try to get into a union apprenticeship program. It'd be four hard years (the apprentices are treated pretty poorly, usually), but you'd have a steady job and good pay and benefits as a union journeyman.
Best of luck in whatever you do.