Ventilation for power supply and controller enclosures is essential in the Australian summer.
These vents (DS-VH-60 available from Switches Plus) require a hole cutout of 62.5mm.
These vents appear to be the same style as the ones organised in an ACL group buy in 2014.
A 60mm fan suits it well (FAN6010C5L for example, available from WES Components).
Secure it to the back of the vent using #4 self tapping screws.
Another possibility is this 90mm rainwater fitting from Bunnings.
This insect screen (also from Bunnings) fits right onto it.
This 50mm vent cowl (again, from Bunnings) may also work when used with a suitable flange.
Click here for more details on the MH1210A unit pictured.