[JT118]

If you had two options for the solar radiation shield and the temp /hum sensor position, would you put it up on the mast below the wind sensors, in the open weather and sun, or on the southern side (opposite side to the equator - Southern Hemisphere / Aust) of the house, on the wall, in the shade most of the time (approx 11 or 12m cable)..?

In theory in the most open part of the garden or area you are going to put the rest of the kit. Presumably this is also where the anemometer mast will go. One is trying to measure ambient conditions. Therefore if you put it on the wall you are effectively measuring a micro-climate created by the wall. The radiation shield should do the work of reflecting the suns direct energy which you also do not want to measure and the design of the shield will allow a free flow of ambient air (which you are trying to measure ) and stop pockets of hot or cold air stalling next to your sensor.