Thanks for the feedback Roger - i agree on most fronts, when I state that cost and efficiency are the greatest barriers I'm referring more to barriers of entry into the industry, not so much real-world barriers, but you still bring up a very valid/important point.
A solar cell is almost entrely ineffective when the sun's down right now...and that's not good enough for self-sufficiency. Fair enough - but based on the technological advances I've seen in the industry..even in the last 5 years, I see the nighttime issue as more of a speed bump than an impassable barrier. It's only a matter of time before somebody discovers an effective way to operate the things we use at night with the solar energy that's stored by some sort of a chargable battery system.
In the meantime, even if the solar nighttime issue isn't solved immediately, the option to run a hybrid style system with solar in the day and more conventional energy generation at night is a possibility - if anything, it's nice that an energy option exists nowadays
Plus, in reference to you mentioning how solar energy's not there when we need it most..well it actually is there..because the time of the day the nation sees the most electrical draw is the early afternoon (or in the morning during wintertime in some regions of the US) - this is just the first thing that popped up when i searched, but it's validated by an engineer at a utility on Yahoo Answers http://answers.yahoo.com/question/index?qid=20090123141510AAaHItm
Again, thank you for reaching out Roger