For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/X11:xfce/openSUSE_Tumbleweed/X11:xfce.repo
zypper refresh
zypper install xfce4-panel
For openSUSE Slowroll run the following as root:
zypper addrepo https://download.opensuse.org/repositories/X11:xfce/openSUSE_Slowroll/X11:xfce.repo
zypper refresh
zypper install xfce4-panel
For openSUSE Factory run the following as root:
zypper addrepo https://download.opensuse.org/repositories/X11:xfce/openSUSE_Factory/X11:xfce.repo
zypper refresh
zypper install xfce4-panel
For 16.0 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/X11:xfce/16.0/X11:xfce.repo
zypper refresh
zypper install xfce4-panel
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/X11:xfce/15.6/X11:xfce.repo
zypper refresh
zypper install xfce4-panel