On 22/05/2014 13:15, Martin Bonner wrote:
On Thursday, May 22, 2014 11:54:48 AM UTC+1, Martin Brown wrote:
I'm a bit surprised it is always the inside. At a guess the outside
cools faster and the frame is slightly too rigid so that the inner
surface is in tension.

That can't be right Martin. If the outer was cool and shrank faster,
it would put the outer in tension and the inner in compression.

Fair point Martin. That makes it even more surprising that the inner
surface goes pop and consistently at night. I still think is is either
related to differential expansion or mistreatment/abuse of the panels.

--
Regards,
Martin Brown