The 19-year-old singer is working on early versions of his songs during numerous visits to the Paramount recording studio in LA, reported Daily Mirror.
"He loves messing around with some of the new songs he's been working on. He's bounced some ideas off his friend Ed Sheeran and has already laid down some vocals.
"Harry's priority is obviously still with 1D. But when he decides the time to go solo has arrived, he's likely to have a project raring to go," a source said.