I can intuitively see why this could work in some closed - canopy, dense forest, perhaps in the tropics, where an individual foliage patch within the canopy might receive direct sunlight only briefly and benefit from increased diffuse light despite a reduction in total solar radiation. (realclimate.org)
[1] Total solar radiation incident upon earth is estimated at 174 PW, [2] for a yearly total of 5,490,905 EJ. (reddit.com)
However, it is also clear that since about 1980, while the total solar radiation, its ultraviolet component, and the cosmic ray intensity all exhibit the 11 - year solar periodicity, there has otherwise been no significant increase in their values. (realclimate.org)