I have a Pyronix Enforcer installed quite recently. The Technician has been back several times to adjust a screw within the siren box but when the Afternoon Sun hits the siren box the Tamper alarm starts.
its a black microswitch. the installer has just moved the Box location from one side to another of the house.
design looks a bit poor as the switch lever can be prevented from fully closing by the mounting shroud.
The alarm did not trigger yesterday. The sun was hot but it's now fitted to a cooler side of the house (earlier sun).
There is now a distinct gap visible behind the box as the switch is fully adjusted out.
It's just poor design, the switch is linked removing the lid, but the activation arm impinges on the switch housing if set low.