25 June 2011: I notice that the first black panel to receive cold glycol has streams of condensation running down the face after the panels have been working. It's not running down the face of the second panel, presumably because it's warmer than the first panel. The input of cold glycol is from a tee at the centre point between the sunboxes, as in this diagram [__]+[__]
It is definitely not a leak of glycol because the reservoir bottle is at normal levels. the droplets are evenly distributed.
Oh, and there's me at the top of the ladder taking the photograph.