It depends where you live and the amount of sun you get and the amount of electricity you use.
Also the financial incentives you get to install the system.
For myself, my electricity usage is quite low ($80/mo average) and my geographic location along with surrounding trees is not optimal so it's not worth it.
A system for my house would be $30k+ after incentives. That's a 31 year payback.
Solar, like wind, is really only cost effective in certain geographic areas, otherwise it is not economically worth it.
Hybrid cars don't even make sense for me as I don't drive enough to recover the additional cost of hybrid car vs. gas only car.
The cost recovery on a hybrid car for me would be around 100,000 miles. Then you figure in the time value of money and it is even farther out.
For example, I have a 2008 car with only 110,000 miles on it. Most of those miles (70,000) were in the first 5 years. I might drive it 3,000 miles a year now.
Most people don't analyze the numbers about these things. It's an emotional decision for them.
The government is pushing this agenda and it makes no sense in many cases.