A high float voltage alarm is displayed when the voltage supplied by the rectifiers is higher than the configurable high float enclosure threshold is set at. The most likely cause of this is the alarm configuration being set wrong.
The threshold for low and high voltage can be set in DCTools. Under Alarms, scroll to the bottom, and expand the Alarm Configuration section. Under that section it is possible to change the values. Default low float is set at 52.8V and high voltage is set at 55.6V.
If the alarm configuration is at default and the alarm is still active, next area to check is the temperature compensation. The temperature compensation is located in DCTools under Control Processes, then Temperature Compensation. The default values for this are for Telect enclosures -4.00 mV/°C/Cell, with a reference temp of 20.0 °C. That means that a low temperature can raise the voltage.
However, by default, the alarm threshold will go up and down with respect to the temperature compensation. However, also under alarm configuration, if Low and High Float tracking is disabled, it will not factor in temperature compensation.