We need large scale coherent perfect absorbers [0] before we can do long distance power beaming. Other than that with a solar pumped laser (spread out over many

We need large scale coherent perfect absorbers [0] before we can do long distance power beaming. Other than that with a solar pumped laser (spread out over many m^2 on the ground to reduce the death-ray-ness) you could get decent efficiency. [0] basically a backwards laser. https://en.m.wikipedia.org/wiki/Coherent_perfect_absorber https://en.m.wikipedia.org/wiki/Coherent_perfect_absorber