Comment by malfist

Comment by malfist 19 hours ago

2 replies

Sure, you absolutely can do it. But material science quickly becomes a major limit.

For something 15% efficient like a high quality PV cell, for every 100 watts you want to be usable on the receiving side, the receiver has to bleed off 566 watts of heat. And that's 566 watts of waste heat that is highly concentrated.

Consider a single residental power circuit. 12A maximum, 120v, that's 1440 watts at delivery. For PV power delivery via laser, that PV would need to dissipate 8 kilowatts of waste heat. One a very small surface

ben_w 16 hours ago

It sounds like you're mistaking PV for a thermal system.

In a PV cell, you have a semiconductor. Semiconductors have this thing called a "band gap", which is the energy needed to get an electron from the valence band to the conduction band: https://en.wikipedia.org/wiki/Band_gap

The limits to efficiency of a solar panel is that sunlight has photons of many energy levels; the photons with energy less than the band gap do nothing, those with more, waste the excess.

A laser can have energy tuned to this band gap, at which point the PV part becomes ~99.9% efficient. (The laser part is not close to that efficiency).

  • malfist 11 hours ago

    I'm not talking about a thermal system, I'm talking about having to deal with the thermals of your inefficiencies. That energy that doesn't get converted to electricity is converted to heat. And you have to deal with it.

    The type of laser based PV that you're taking about that's highly tuned is at maximum 27% efficient. Not 99%.

    That's a 73% waste you have to manage