A data monitoring device that plugs externally into the bottom of the inverter. The logger relays information from the inverter to the Solis monitoring platform, SolisCloud. It can connect to a local router through Wi-Fi or to a 4G cellular network. If the Wi-Fi network goes down, the logger automatically switches to using the cellular network to limit the loss of data. There are two versions of the logger, USB for S6 hybrid inverter models and 4-pin for all other Solis inverter models.