Solar water heater advice wanted

[Sprinter 1 cup]

Fill up tank/pipe at 9 am Warm water on roof during day, summer only, drain into . I would call immersion tank like we had befor combi boiler at night so maybe 2 pumps or gravity. Turn element Extra heat on to shower
Some people Carrie a 12 month van all year round. but old British camper vans are good for summer. I don't mind winterizing my van. As I have a toolbox, so adding or removing as and when is about fule.
Humble road Goerge last video post has a heat exchanger but 150 degrees at hot tank.

 

[wildebus]

Fill up tank/pipe at 9 am Warm water on roof during day, summer only, drain into . I would call immersion tank like we had befor combi boiler at night so maybe 2 pumps or gravity. Turn element Extra heat on to shower
Some people Carrie a 12 month van all year round. but old British camper vans are good for summer. I don't mind winterizing my van. As I have a toolbox, so adding or removing as and when is about fule.
Humble road Goerge last video post has a heat exchanger but 150 degrees at hot tank.

The temp at the hot tank doesn't matter if too hot (you actually want it as hot as can be if you are using 'free' power to heat it).
You just fit a TMV (Thermostatic Mixing Valve) set to the appropriate temp and that will automatically mix the hot water with the cold to ensure it is at a safe temperature. On the home solar water system I installed in my house, I installed a TMV for this precise purpose.

PS. There is also the question of protecting against Legionnaires Disease, which can be present in warm water and a hot water supply should be heated above a certain value to prevent/kill it. Too low a temp can be an issue on that front (which is why hot water + TMV is the safest option).
From Wikipedia...
" The bacteria grow best at warm temperatures and thrive at water temperatures between 25 and 45 °C (77 and 113 °F), with an optimum temperature of 35 °C (95 °F). Temperatures above 60 °C (140 °F) kill the bacteria."

 

[Nabsim]

If I ever wire the 1Kw immersion element in it has set points up to 85C, the coolant element will heat to whatever the engine coolant temp gets to. There is a TMV on the outlet of the calorifier

 

[Sprinter 1 cup]

Got you tub and any thing above sixty stopped le gen airs