Their documentation is not exactly clear,
but you have a 25A "controller" and a 50A load.
The diversion load is listed as 'optional'. I have to assume that means the PV power goes to the load.
PVs are like a current source. 20A.
The 50A load is about 0.28 ohms.
I^2R=100W in the 600W heater, at the very best. So much for all that bragging about how efficient it is.
With wind, the diversion load is still listed as required. Try to realistically size a suitable load for that. It can't be done.
Especially if you want to efficiently heat water, without destroying the turbine.
That controller does not even have a provision to stop night time discharge through it, like a blocking diode.
350W of PV, wire, brackets, water heater, 12V element, plumbing, etc. to put 100W peak into the water?
For the system to work efficiently, or possibly work at all, need to get a decent controller that functions like a normal controller. And that one sure ain't it.