I wouldn't argue that buying electricity from the grid is cheaper, but folks generally go to PV when it's too expensive to run power lines, or when their grid service is unreliable. I agree that it would be more cost-effective to add insulation and switch to energy efficient lights and appliances, but what do you do after you've done that? I also agree that you'll probably get a bigger return on your investment with mutual funds, but what fun is that? If you continue to burn fossil fuels you are contributing to several problems; global warming, the destruction of mountains in Appalachia, poisoning of rivers, streams, and air, etc. So why not try this:

Once you've completed your energy efficiency upgrades, and have secured your retirement with a significant investment portfolio, why not do something that will benefit your children and future generations.

And by the way, not everyone lies about the economics of solar power. The folks on the discussion forums I visit always try to avoid overstating the capabilities of the systems being discussed. I typically get more from my system than it is supposed to produce. Additionally, it really came in handy on several occasions when the grid power failed for extended periods of time.

John
http://solarjohn.blogspot.com