The conclusion seems rather to be “human metabolism is less efficient than solar panels,” which, while perhaps true, has limited bearing on the question of whether or not the brain is thermodynamically efficient as a computer when compared to current or future AI. The latter is the question that recent discussion has been focused on, and to which the “No - ” in the title makes it seem like you’re responding.
Moreover, while a quick Google search turns up 100W as the average resting power output of a person, another search suggests the brain is only responsible for about 20% of energy consumption per time. Adding this to your analysis gives .13% “efficiency” in the sense that you’re using it, so the brain still outperforms AI even on this admittedly rather odd sunlight-to-capability metric.
Sure, one can always embed a game inside another one and so alter the overall expectation values how one likes. That said, we still only want to play the meta-game if it had positive expectation value, no?