The 153IR modules draw much less than 1 Amp of current. #20 stranded or solid is more than adequate conductivity-wise. I suggest whichever method is easier for you installation-wise. Likewise, if going with Menards diagram #2, the Menards station also draws much less than 1 Amp of current. Again, if #20 is what you have (stranded or solid) you're good to go.