J3J33J333 said:
I think there are some thermophotovoltaics in the works that reach 40% efficiency. Also seen some people use materials to combine photons into a new wavelength so maybe that'd be a path to convert the IR to near IR, too.
I suspect these are heroic numbers, the kind of thing a grad student does but that you can't buy. For example, this from
Wikipedia:
"The upper limit for efficiency in TPVs (and all systems that convert heat energy to work) is the
Carnot efficiency, that of an ideal
heat engine. This efficiency is given by:
where Tcell is the temperature of the PV converter. Practical systems can achieve Tcell= ~300 K and Temit= ~1800 K, giving a maximum possible efficiency of ~83%. This assumes the PV converts the radiation into electrical energy without losses, such as thermalization or
Joule heating, though in reality the photovoltaic inefficiency is quite significant. In real devices, as of 2021, the maximum demonstrated efficiency in the laboratory was 35% with an emitter temperature of 1,773 K.
[10] This is the efficiency in terms of heat input being converted to electrical power. In complete TPV systems, a necessarily lower total system efficiency may be cited including the source of heat, so for example, fuel-based TPV systems may report efficiencies in terms of fuel-energy to electrical energy, in which case 5% is considered a "world record" level of efficiency.
[11] Real-world efficiencies are reduced by such effects as heat transfer losses, electrical conversion efficiency (TPV voltage outputs are often quite low), and losses due to active cooling of the PV cell."
Can you really heat an object to 1800K with your IR radiation?