[Gravityloss]

Concentrators have problems.

If you use them with solar panels, then your panel will heat up and its efficiency will drop. Maybe lifetime as well. If you use a thermoelectric generator, you then have wearing mechanical low efficiency systems on board.

In both cases you need to reject heat, which is hard in space.

They also require precise pointing.

There's also the problem of beaming the power to earth. If you're in low orbit, there would have to be lots of receiving stations and the power would be intermittent unless you had a big constellation. And all the problems with inclination and the spinning earth... If you're in geostationary orbit, your sending and receiving antennas would need to grow huge.

What about beaming between satellites? You'd need a laser for that. Maybe they're becoming quite small and efficient with modern semiconductor technology developed for military uses. Still the receiving end might have low efficiency.

[schiffern]

Yep, after writing all that I realized that heat rejection is going to be a problem. Dissipating 8.4 MW is no easy feat in orbit.

At that point the balance of system probably shifts to thin film PV. There would need to be a lot of advancement in that area before such a project becomes practical.

>What about beaming between satellites? You'd need a laser for that.

I was picturing a microwave rectenna, actually.

[Gravityloss]

If you use a laser, the receiving satellite wouldn't need extra hardware, it could use its ordinary solar panels, if they were pointed in the right direction.