I'm a bit of a skeptic concerning the current economic viability of alternative and renewable energy sources in terms of existing technology, although I believe they're essential in the long term. Nevertheless, the just-completed Topaz Solar Farm in California is pretty impressive. It covers about 4,700 acres and uses 9 million solar panels to produce about 550 megawatts of electricity at full output - enough to power 180,000 homes.
Here it is while still under construction earlier this year. Watch the video in full-screen mode for the best impression.
Even though I don't think this particular exercise in renewable energy will prove self-supporting, financially speaking, I've got to admit . . . at least it looks impressive.