Is solar affordable now? We had it quoted for our home, and to cover 60-75% of our annual usage, the system cost ~ 20x-28x our annual usage depending on which system we chose, with a life-span of, wait for it, 15 years and warranty of 10.
If it wasn't for heavy, heavy government subsidies in this space (some states match 50-75% of the up-front cost over the course of a year or two), I am not convinced it would be popular, at all, for regular Joe Schmoe.
Yes, the effeciency rate of solar is what makes it "worth it" or not, and within the last couple of years it has hit a sweet spot where in many to most cases it is "worth" the investment costs. That said, you need to watch out for unscrupulous installers not installing the latest panel tech, or installers who overcharge, etc, and it is preferable to research and utilize all available subsidies you can get your hands on (tax deductions, insurance, local electricity policies, etc).
The tech itself is at the right level now, it's the middle men and bureaucracies or bad rates that are the main problem. Source: family member who has overseen installation and maintenance of many major solar installations.
