Sometimes we need solitude to deal privately with pain. It's in the Bible, Matthew 14:13, NIV. "When Jesus heard what had happened, He withdrew by boat privately to a solitary place."
Solitude can be valuable for effective prayer. It's in the Bible, Matthew 14:23-24, TLB. "Then afterwards He went up into the hills to pray." Mark 1:35, NIV says, "Very early in the morning, while it was still dark, Jesus got up. Left the house and went off to a solitary place, where He prayed."
If Jesus needed solitude for quiet reflection, how much more do we? It's in the Bible, Luke 4:42, TLB. "Early the next morning He went out into the desert. The crowds searched everywhere for Him, and when they finally found Him, they begged Him not to leave them but to stay at Capernaum."