My physics is getting a bit foggy, but I'm pretty sure I remember a lecture in which we were told that 30% transmission efficiency is actually about the best we

My physics is getting a bit foggy, but I'm pretty sure I remember a lecture in which we were told that 30% transmission efficiency is actually about the best we can achieve with current materials science (without going to insanely expensive exotic solutions that don't scale or require non-room-temperature conditions). This is part of why the idea of switching from big centralized power-plants to small localized plants is a big potential win.