Is it possible to set the opacity of the tiles in google maps v3?
I have see in done for overlays but I want to make the actual map tiles slightly transparent.
Why would you make the tiles transparent, if they'll always be base "layer" for the map? Are you trying to somehow add an overlay behind the map tiles?
You can adjust the map tiles using the style feature of the Google Maps API:
https://developers.google.com/maps/documentation/javascript/cloud-customization