The 23-year-old Londoner signed for league rivals Dagenham & Redbridge in October 2016, although he spent the last months of the season on loan at National League South outfit Bishop`s Stortford.
The 6`5” striker also had a trial with EFL League Two side Cambridge United shortly before joining Dagenham and although the U’s didn’t sign him, they are keen to monitor his progress and development.
A prolific goalscorer in the lower echelons of the non-League Pyramid earlier in his career with the likes of Clapton, Bowers & Pitsea and Romford, Barnwell is keen to prove he can do it at a higher level with The Moors.
Manager Liam McDonald said: "Shomari is a big, strong and quick forward who will add something different to our squad and complement the exciting strikers we already have.
"He's attracted a lot of interest and we're delighted he's chosen Solihull to be his home next season. He's scored goals at lower levels and had a successful loan in the National League South last season - now he's ready to take that on to the next level".