"The current estimate of the earth’s annual photosynthesis (by terrestrial plants and algae in the ocean) is about 200 billion tons of carbon per year."
...
The total energy stored (worldwide) in the sugar produced by photosynthesis is about 2 x 1021 calories per year.

Now all that remains is to take the ratio of energy stored in sugars by photosynthesis to total energy input from the sun. This value comes out to be about 0.2%. "
http://www.ccmr.cornell.edu/education/ask/index.html?quid=1021

When one consider how much solar energy hits this planet, that's a lot of energy.
Does anyone have better numbers than 200 billion tons of CO2 used each year by plant photosynthesis [that would somewhere around 8 times the amount CO2 emission by human activity]. Or the number of 0.2% of all solar energy or somewhere around 2 watts per sq meter on average. Or does anyone know what type of areas with plants use most amount of solar power per square meter?
It says that a leaf has 5% energy efficiency, does mean that is say a rainforest which blocks a lot of sunlight, that these trees would gettting around 50 watts per meter?

Oh,
"Solar radiation striking the earth on an annual basis is equivalent to 178,000 terawatts"
And:
"Only light within the wavelength range of 400 to 700 nm (photosynthetically active radiation, PAR) can be utilized by plants, effectively allowing only 45 % of total solar energy to be utilized for photosynthesis. Furthermore, fixation of one CO2 molecule during photosynthesis, necessitates a quantum requirement of ten (or more), which results in a maximum utilization of only 25% of the PAR absorbed by the photosynthetic system. On the basis of these limitations, the theoretical maximum efficiency of solar energy conversion is approximately 11%. In practice, however, the magnitude of photosynthetic efficiency observed in the field, is further decreased by factors such as poor absorption of sunlight due to its reflection, respiration requirements of photosynthesis and the need for optimal solar radiation levels. The net result being an overall photosynthetic efficiency of between 3 and 6% of total solar radiation."
http://www.fao.org/docrep/w7241e/w7241e05.htm