Perhaps I can add to that.
There are both federal and state incentives and programs to encourage energy efficiency and renewables in homes. California has led most of the United States with building codes that require energy-efficient homes, so many of the homes now built require practically no heating or cooling under normal operating systems. Homeowners can also get tax credits for various efficiency measures at both state and federal levels for investing in energy efficiency and solar.
Recently my own town of Berkeley, California, has undertaken a new scheme to help pay for and capitalize solar installations on roofs of homes in such a way that they're carried on your taxes. So if you sell the home the buyer of that home actually has to continue paying for the solar installation. But the result is that the owner of the home can get a very large solar installation for practically no initial capital investment.