How I directly wired a hot water heater to solar panels using relays for only $30

This is the solution for how to wire a resistive element hot water tank to a VDC solar panel array for a minimal hardware cost. The two relays are SS 220 VDC 20 amp load side with a 3VDC-32VDC 30mW control side. Major lessons learned was to wire both top and bottom thermostats in series on the control side otherwise you'll pop your overpressure valve.

[@JR-xw5dk]

Do you have a pressure tank in the system? Too high pressure may pop a hole of pop a fitting in the future.
I have a small pressure tank(expansion tank)for our water heater. I wish there was a very cheap pressure logger. I have grandkids and maybe they can build me one.
Thanks for sharing
😮

[@opera5714]

Definitely that tank needs an expansion tank, a tank that size will expand over a pint. That doesn't sound like much but that can over pressure the tank and blow the pressure relief. In solar this is even a greater problem because the temperature swings are so great. That tank is not going over temp.
In PV water heating systems, the upper over temp thermostat should always be wired in series with the PV array power. Contacts may not like repeated openings, but they will always work once. Not doing this is dangerous.