No requirement to install a separate DC isolator for SolarEdge HD Wave single phase inverter
There is no requirement to install an additional DC isolator adjacent to the SolarEdge HD Wave inverter. However sound electrical practices are to be maintained at all times and the replaceable cover is required to be retained to enable the switch box to be sealed if the inverter is removed.
The result of removing the AC from the inverter, triggers the safe mode of the DC optimisers fitted in/to the panels and reduces the DC voltage to approximately one (1) volt per panel. Therefore the voltage presented for a string of 27 panels will be 27 volts DC i.e. ELV (<120 V Ripple Free DC).
The instructions included in the SolarEdge manual for the above device describes the requirements and steps for replacement.