Here's someone who knows more about the subject than I do. From Scientific American:
The founder and chief scientific officer of Ausra weighs in on the hurdles facing his industry
What technical obstacles currently most curtail the growth of solar power (particularly solar thermal)? What are the prospects for overcoming them in the near future and the longer-term?
The biggest obstacles are ability to scale, long-term reliability and interruptibility due to clouds and the daily solar cycle. Ausra's core technology, the Compact Linear Fresnel Reflector (CLFR) system, is simple and robust. We are optimizing for the lowest cost of energy, not highest technical sophistication. This combination results in the best value to our customers and high reliability.
CLFR uses an array of relatively flat mirrors that reflect sunlight to boil water in elevated tubes, producing steam that drives turbines to generate electricity. CLFR is also the most land-efficient solar technology. By using nearly flat mirrors, water/steam heat transfer, and commodity materials, we are also able to achieve significant cost savings and rapid deployment. Additionally, by using our special reflector geometry, we are able to have a greater density of reflectors in the area and use about half of the ground area of competing technologies. Our systems produce steam for stand-alone, large-scale solar power plants as well as to augment energy output and reduce emissions at existing conventional power plants. The steam can also be used for industrial applications, such as food processing and enhanced oil recovery.
Unlike photovoltaic (PV) or other concentrated solar technologies, which lose output immediately when clouds come over, our technology has 20 to 30 minutes of stored capacity, so it can adjust to weather changes or other factors affecting the electric grid. CLFR hybrid plants (with natural gas boilers) can also provide firm capacity to the grid. We are currently proving our CLFR technology at our five-megawatt demonstration and test facility in Bakersfield, Calif. This is the first of its kind in the U.S. and the first large-scale solar thermal plant to go online in California in nearly 20 years....MORE