Is solitude the only real way to true enlightenment?

You have to see yourself first. Actually see. Yes, this requires separating yourself from the meme soup you are living in and watching how your own body and mind works from moment to moment. It takes a period of silence (and minimal social interaction) to slow down enough to actually see yourself in this intimate fashion. Once you know yourself well, and understand there is no permanence anywhere you look, you will detect some strange stirrings that indicate that underneath the weird conventions of society every sentient thing "out there" is actually you. We are all the same person. It's rather astonishing and the realization takes a few years/decades to emerge as head-smacking obvious.