That shouldn't be notably more efficient. Sure, solar panels operate at a significantly higher efficiency on the moon due to no atmosphere to diffuse the sun's

That shouldn't be notably more efficient. Sure, solar panels operate at a significantly higher efficiency on the moon due to no atmosphere to diffuse the sun's energy... but then you have to pay the atmosphere cost to get it to Earth. Your suggestion presupposes that we can transfer energy through the atmosphere more efficiently than the energy of the sun is transferred through it. We certainly could do so if we had a space elevator (but at that point just put the solar panels in geostationary orbit with the elevator, not on the moon).