What is this for?
This is an American-made frost protection valve, that could save you well over $3000
Yes, the weather is cold, and there is lots of frost about. It just takes ONE frost and your solar panels could be damaged beyond repair.
So, if you live in a frost-prone area, and you have old or leaking frost protection valves, take this opportunity to replace them with the non-failure type.
Get all the information here: https://www.solazone.com.au/solar-hotwater/frost-protection-valves