The azure photovoltaic modules may hold a cherished place in America's collective memory since the widely televised broadcasts of NASA's Apollo space program and Skylab in the 1970s.

Meanwhile, thermal solar power, which uses an array of mirrors to magnify the heat of the sun and produce steam to drive electric generators, has been on the job around the world for decades.

Thermal solar holds a longer track record with utility companies, despite its less-visible position in the alternative-energy world, according to Santiago Seage, chief executive of Abengoa Solar.

Santiago Seage, CEO of Abengoa Solar, talks about how thermal solar harvests the sun's rays to turn water into steam, driving a turbine and creating electricity, even at night."From a 'number of systems' perspective, photovoltaics caught on earlier (as used in homes and commercial buildings), but from a 'electricity generated'view, concentrated solar power caught on earlier," he commented in an interview with MarketWatch.