I am considering drain back solar system for domestic hot water, and was wondering about durability of the solar panels (collectors) when used in such system.
This video seems to do good explanation of the Drain Back Solar Systems principle:
http://youtu.be/qOXcbsjUOZw
As I understand the principle of Drain Back Solar Systems, once the set high limit temperature for the drainback tank water/glycol is reached - the controller shuts off the pump and stops the water flow. This stops the tank water from overheating, but then the collector itself is not transferring the collected temperature. Since this can/will happen often (depending of the drainback water tank versus the solar collector ratio), how safe is this prolonged "dry stagnation" for the collector condition and durability?
It seems that solar panels/collectors intended for use with Drain Back Solar Hot Water Systems, should be made with bigger tolerance for high temperatures. Or any collector will do?
Can somebody share some insight or experience, how durable are solar panels/collectors when used in drain back system?
