Once you’ve installed an OpenSSH server, you also have an SFTP server. In Solaris, you should check if the subsystem is configured properly or not.
Configuration is stored in /etc/ssh/sshd_config
file:
# sftp subsystem
Subsystem sftp internal-sftp
PubkeyAuthentication yes
Restart the service:
svcadm refresh svc:/network/ssh:default