"A" writes:

I photographed this on 01/04/2006 in mid morning as I was hauling the first panel up to the roof. It was new out of its cardboard box. The shadow on it is from the lines and pegs on the clothes dryer behind the camera. Note the orange cord. It was a loop across the protruding pipe ends at the top end. The loop provided an attachment for the hauling line which passed through a pulley which itself was slung on a cord looped around an access hatch on the roof. I was concerned that by applying strain to the pipe end I could have damaged the internal structure; it was your web site information that relieved me of this doubt. You can just see the pipes inside.

This is how it looked yesterday afternoon 25/08/2007. Comparing the two pics, the same digital camera and settings were used, there is a difference in colour. The earlier one was strong deep blue, this is middling strong brown. The angle to the horizontal is nearly the same and the time is roughly four hours later. The glass looks less opaque. The sun has traveled further west. I couldn’t see the ribs in the panel in 2006 as clearly as I can now. Allowing for small differences it looks as though there has been a change in the internal conditions in the panel.

Note from Gary: the left hand panel may be more affected because the frost protection function may be reducing the amount of condensation in the right panel more than the other.
Is that down to damp affecting the flexible mask overlying the pipes? I say flexible because after contacting the supplier he said that there are four holes on the underside, so I explored with a piece of stiff wire and poked it up and felt and saw the overlay material deflected up toward the glass. I did that to prove that there was a hole and that there was nothing blocking it. Before I drilled the half inch
It took sheer determination to first drill a 1/16 hole as a leader followed by the half inch bit. Then I realised that the 20mm dia pipe inside allowed a fair bit of space around it above and below, probably 25mm top and bottom. Then I drilled a half inch hole top side just under the glass. That way I realised that I could suck saturated air out and replace it with dry air through the top hole.