Where are you located? if in the US , a schedule 40 , galvanized, 3/4 inch as called on the shelf, fits perfect. As Canada and the US have used the same standardized pipe size, although converted to metric in Canada , you should be able to pick one up at the local HW store
And is what I use (the 3/4" is the interior dimension (ID), the outside is perfect.
And you can drop the cable (charging cable, if you use it) , straight down and not use the slits, which would be for an exterior mounted cable.