I saw some at the Build Boston show in November, and that is the number the person in the booth mentioned. I have also heard from any number of sources that solar heat collectors are far more efficient than solar PV -- because PV only uses a small portion of the spectrum, and the mechanism is not as effective. These new (near) vacuum tube systems work very well because virtually all the light enters the tube, and most of the heat that is created (infrared) is kept in because of the vacuum. The heatpipes are efficient because they have a state change material inside. I'm sure that the greatest inefficiency is in the heat exchanger at the top of the tube.
The parabolic solar heat collectors are also very efficient, but they have to do vertical tracking.
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