If you point concentrated solar at a vantablack object, heatsinked to this 40% efficient TPV, do you get an easy 39.94% efficiency, easily outpacing mass produced photovoltaic or am I missing a loss?
Such multi-junction photovoltaic cells, but optimized for the higher temperature of the Sun, have existed for many years and efficiencies over 45% are well known.
So there is no point in heating anything, the concentrated solar light must be directed to an appropriate multi-junction photovoltaic cell, for the best efficiency.
Despite their very high efficiency, the multi-junction photovoltaic cells are seldom used for solar energy, because they are expensive, so they can only be used together with light-concentrating mirrors, to achieve a reasonable cost.
Even with mirrors, the price is still much higher than for normal solar panels, so they might be chosen only when space constraints would prohibit the use of a larger area with solar panels.
I can't seem to find any place that sells these with a brief search, so I'm thinking 1000x.
Having more efficient cells would give you a few more miles I presume. Not too useful for the everyday user, but if you're doing an off grid trip it would be very useful if you camp somewhere and let your car charge for a few days. I guess might as well roll out some proper panels in that case though.
Planes do have a reasonably large wing surface area that could be panelled up if they're not too heavy (you can make quite large RC planes fly perpetually in the sun even with regular monocrystalline panels) so there would definitely be some fuel savings from it if you had like a hydrogen powered jet that already uses electric propulsion.
They have been used for solar panels in satellites or space probes, where maximum efficiency is more important than the price, and in experimental solar plants with movable mirrors that concentrate the solar light from a very large area onto a small photovoltaic cell.
In both applications, the complete systems are very expensive and the cost of the photovoltaic cells is a very small part of the total.
However, extracting exergy (electricity is pure exergy) from a flow of energy is the tricky part and will always be associated with efficiencies way below unity, based on fundamental principles.
Also, you don't need Vantablack, a regular cavity absorber would be fine.)
But maybe not, the glowing comes from black body radiation, so the vantablack material would presumably glow as well (ironically). As long as the heatsink coupling did not block the visible "white" light produced, or glowed itself, then at least the photons from the back would get used. I expect that getting a heatsink paste rated for 2200 C is ... challenging, but, conveniently, you'd do better if you just skipped the paste.
Liquid metal is some of the best performing thermal paste around. In computer applications that's normally an alloy made from Gallium, Indium and Tin, but at 2200C the majority of metals should work. Maybe Gold to reduce oxidation.
[0] https://www.sciencedirect.com/topics/engineering/concentrate...