There is no “dark side of the moon”. All of the moon gets the same amount of illumination during the 28 day orbit of the earth. There is the “far side of the moon”, which we don’t see from the earth.
I know. I know. I was just making fun of the title. ;)
Still, anywhere on the Moon except the poles gets 14 days of light, followed by 14 days of darkness. A solar powered probe would presumably “sleep” a lot. I would opt for the Seiko Springdrive.