[clord]

Have to consider the amount of heat moved, too. It's the same difference as between pressure and volume, or volts and amps. Perhaps it can't move a large volume of heat quickly, but can achieve a decent temperature difference given enough time?

[LeifCarrotson]

And even if it can, I am reasonably confident (from my arm chair here) that this combination of relying on a narrow band of passive IR emissions to drive a heat engine will be less effective than a photovoltaic cell generating electricity directly from incoming visible radiation across a relatively broad frequency band.

[photojosh]

Ah, but only one of those still operates in the dark.

[Retric]

50C is not much for heat engines your limited to under 15% effecency in the best theoretical case. So solar + battery is going to be a net win unless your thinking of flipping panels at night for ~1% more power over pure solar panels which is silly from a cost perspective.

[ianai]

I thought solar was widely favored long term, but it's going to be a long time before it establishes that position.