Looks like you’ve got yours set up - good job! My DHW tank has two ports or “thermowells” which are small tubes that extend a cm or two into the water tank; these designed for measure water temperature with thermocouples. They weren’t being used, so I stuck a DS18B20 into each and packed a little insulation over them.
Here’s my latest chart:
The red line shows the tank upper temperature - the rapid rises are when the boiler kicks on. The blue shows lower tank temperature, which rises when my solar collectors provide some heat (yellow line). (this tank has two heat exchangers - the exchanger for the boiler is in the middle of the tank, the one for the solar input is at the bottom). I like to see that I’m getting some heat from the sun even on cold February days! During the summer, the tank lower temperature will often rise to be equal to the tank upper temperature - this shows I’ve got a fully heated tank. I can go for weeks in the summer with the boiler turned off as long as the sun shines! The graphic widget on the left gives a view of how much heat is in the tank and helps us decide whether to do laundry or wait for a sunnier day.