Ciao 

The connection between the Powerchute application, the ESXi host (or the vCenter) and the UPS takes place via the network (therefore the UPS must have the management network card installed, it is not always included in the UPS).

You can also manage individual ESXi nodes (I've always used it for managing infrastructures with vCenter) and communication takes place by creating users on ESXi with specific permissions (ssh is not necessary).