More efficient solar energy

I guess this technology is old, and this article is a few years old, but I recently found out about these things called Stirling Engines.

http://www.wired.com/science/planetearth/news/2005/11/69528

The design dates back to the 1800s, and these engines are approximately 2-3 times more efficient than typical photovoltaic cells (normal solar panels we are used to). Southern California Edison and San Diego Gas & Electric are working with Stirling Energy Systems to build 2 plants that should produce approximately 800 megawatts. To give you an idea, in 2005 the US only had about 400 megawatts of solar capacity. A typical coal or gas power plant delivers 500-1000 megawatts of electricity. Is this the end all solution to renewable energy? Nope, but it is a big step in the right direction.