I have been so obsessed with documenting the system performance that my wife has started teasing me about my "affair" with the water heater.  To which I reply "Yeah, once you've had a water heater baby, you never go back.  They're hot!".

But seriously, when I tire of logging data I will need a conveniently located basic system monitor, or a "dashboard" if you will.  So I put a dual display up next to the kitchen sink which is right above the water heater in the basement.  This unit displays the collector temperature (from the pipe as it enters the Solar Wand just above the tank) and the temperature at the top of the tank.  There are 2 lights, a green one indicates the pump circulation, and a flashing red one that warns of low fluid in the overflow reservoir above the collectors.  I will probably add another over temp sensor that indicates when the pump shuts off due to excess temperature in the tank.

I tucked the collector sensor under a piece of insulation wrapped around the tube that enters the Solar Wand, and the tank sensor I poked deep under the tank insulation at the top of the tank.  All the wires connect to a  terminal strip on the back wall.  The sensors and meters are powered by a wall transformer that provides 12 Volts at 100mA so the gauge will run at night.

At some point in the future I might even build a graphical LCD panel that shows the readings for the last 24 hours.