On the thermodynamics of the difference between energy transfer rate and heat engine efficiency.

We study the difference between the energy transfer rate and the engine efficiency with a microscopic model, widely used in the theoretical description of solar cells, as well as in light-harvesting systems. We show no violation of the second law of thermodynamics by correctly assessing the useful output work, even with the simple model treating the later work conversion as a simple "sink". [ABSTRACT FROM AUTHOR]