This paper considers a model for the solar cell as a mechanical open-cycle thermodynamic engine where chemical potential is produced in an isochoric process corresponding to the thermalization of electron–hole pairs. Expansion of the beam under one-sun illumination and the current generation are described as lost isothermal work. More generally, voltage produced in an open-cycle process corresponds to availability, leading to a correction to the Shockley–Queisser detailed balance limit.
Tom Markvart (Tue,) studied this question.