I'm helping my son manage his energy bill. One idea I have is to reduce the "head" required by a pump by closing the vacuum break (in summer) at the top of the solar panels (or moving it to a lower point in the panel plumbing network) so that the pump is aided by the siphoning within the solar panel loop. While this will reduce the pressure the pump must overcome by, say 15psi, as discussed on this thread, the gauge pressure would go negative at the top of the solar panels. How can I determine whether the negative pressure will cause flexing and/or collapse of the panels, that could result in increased internal resistance or, worse, physical damage to the panels?
I may or may not be able to identify the manufacturer of the panels, as they were installed before my son bought the house.