Do you mean physically or in spiritual principle? Your question is severely vague.
Assuming you're asking here, you mean the latter. It varies considerably by tradition and personal opinion, and all boils down to belief. If you choose to work with so-called solar and lunar energy, I'd suggest researching in whichever specific tradition you're studying now, and use those correspondences. But apply your own experiences to develop your personal knowledge on the topic.
For example, some traditions hold the sun as masculine and the moon feminine, while some hold them both as one or the other, or as the opposite. Some hold them as very similar or different things. So don't trust any one answer as the and all and be all of the solution.