Even if moonlight could be harvested for energy, the amount of energy is infinitesimal and would have absolutely zero practical use.

The energy of moonlight is only 1 millionth of sun light, and it is very doubtful that solar panels with low enough internal resistance will ever exist to allow any measurable energy output.

The theoretical energy is only 0.003 w/m² with a clear sky at full moon. This is such a small amount of energy that I doubt it will ever be worth pursuing. A similar amount of energy can be picked up from ambient radio waves, that would have the clear advantage of being way more stable working 24/7.

Moonlight can be a nice light source at night, and it can look pretty, but as an energy source it is absolutely useless.