The Energy Dudget

Superefficient, Cost-Effective Solar Cell Breaks Conversion Records: SCIAM Science News Dec 8, 2006
""We have somewhere between 20 and 30 layers of semiconductor material," explains David Lillington, president of Spectrolab, Inc., . . . The resulting efficiency nearly doubles that of standard silicon solar cells, which hover at 22 percent. That gain requires, however, the use of light-concentrating devices, such as miniature plastic lenses and mirrors. The new solar cell achieved 40.7 percent efficiency under such concentrated light at the testing center at the National Renewable Energy Laboratory in Colorado. One cell of just 0.26685 square centimeter (or roughly 0.04 square inch) pumped out 2.6 watts of electricity when bathed at the maximum light concentration.""Even though installed cells would require concentrators, the fact that fewer cells can produce the same amount of power--and that similar cells are already widely produced--means this system could potentially generate electricity in the range of 8 to 10 cents per kilowatt-hour--roughly equal to consumer electricity prices today." "the record-breaking solar cells are at least 12 months away from full-scale manufacturing, Lillington says. "Before we put this new cell into production it needs to go through a qualification process to make sure it can withstand the rigors of the environment." Of course, its Martian peers have lasted 28 months in that harsh, alien environment.
[NOTE: The Mars rovers worked (and still are) much longer than predicted, with the rooftop collectors  -- surprise! -- getting a brush-off now and then by a passing dust storm. And all this with a solar flux of about 600W/m^2 i.e. only 44% of Earth's.]
And the triple-junction solar cell may not hold the efficiency record for long. "We are also looking at four-, five-, even six-junction solar cells," Lillington notes. "There are at least three or four different approaches to take the efficiency into the 45 percent range."
Based on p.4 of the paper, quoting from
"One of the most efficient crop plants is sugar cane, which has been shown to store UP TO 1% of the incident visible radiation over a perid of one year. . . . . The annual conversion efficiency of corn, wheat, rice, potatoes and soybeans TYPICALLY RANGES from 0.1-0.4% (Odum, 1971)"
I haven't been able to come up with other original data on food crop experiments comparing their photosynthetic efficiency, other than the above quoted book, which is to be found in the BGU library:
Odum, Howard T., 1971. Environment, Power, and Society. John Wiley & Sons. ISBN 047165275X
Copy found: BGU Ben-Gurion U. 004990123 
The nearest, albeit for algae, was the following article:
"The combination of algal and anaerobic waste treatment in a bioregenerative farm system"
Gedaliah Shelef,  Department of Environmental and Water Resources Engineering, Technion - Israel Institute of Technology, Haifa, Israel
SEE TABLE 2. Summary of Algae Production Data Based on Technion Pilot Plant and Field-Scale Pond Operation:
Average daily incident irradiance (total)    450 cal/cm²-day
Average daily incident photosynthetically available irradiance  202 cal/cm² day
Photosynthetic light conversion efficiency (based on total irradiance)  2.96%
Photosynthetic light conversion efficiency (based on photo-  
synthetically available irradiance)     6.59%

Yield Potential, Plant Assimilatory Capacity, and Metabolic Efficiencies
PROBLEM:  Wiki: Earth Energy Budget:
 give estimated world annual energy use as 15tW, when its quoting from
which gives the figure of 446x10^15Btu (= 130x10^15Whrs)    ??????????????