Pie in the sky?

Numbers. Just numbers, for now. The Earth receives around 12.2 million watt-hours per square mile per year. This equates, worldwide, to 274,000,000 gigawatt years. Another way of putting that is that we receive 8.2 million quads (quadrillion Btu). With me so far? Now, the earth's population, use around 400 quads to serve all our energy needs. So, is it possible that we could eventually serve all our energy needs from solar radiation alone? Yup.

It's not easy. We're up against lots of problems. There are definitely some huge technological hurdles to be overcome, but we are a race which managed to put men on the moon using technology less powerful than your mobile phone. Of course it's possible and if we all want it badly enough, it's likely. Don't let anyone tell you it can't be done.