Photosynthesis vs solar panels
Blankenship and colleagues compared photosynthesis with solar-powered water splitting: photovoltaics are more efficient annually, but photosynthesis comes within a factor of 2–3 under optimal short-term conditions.
As reported in: Blankenship, Tiede, Barber et al. (2011). Comparing Photosynthetic and Photovoltaic Efficiencies and Recognizing the Potential for Improvement. Science. doi:10.1126/science.1200165