So I built a copper heat exchanger and mounted 2 flat plate collectors on the roof, plumed it all in and insulated.
The Solar panel in the middle runs the Glycol pump, when the sun shines the pump runs, when a cloud comes over the pump slows down and in the evening the pump stops completely.
When the glycol temp reaches 5 degrees above the hot water tank the flow valve opens and the system begins to heat the DHW .
Works fantastic !
So far in testing the system will heat 350 liters of water to +60c even in winter with an outside temp of - 30c
