The diagram below (on the left) represents the first part of the solar thermal storage system that was up and running as of Feb 19, 2010. The storage tank is represented on the left in the image. Water is pulled from the bottom of the tank and pumped through the heat exchanger where it gets very hot. It is then deposited at the top of the tank, where it drips back down to the bottom heating up the sand along the way.
The right side of this diagram shows the solar collector loop where a water/glycol mixture is pumped through the collector where it gathers a lot of heat, and then pumped through the heat exchanger giving that heat to the storage tank.
The graph below (on the right) shows the temperature in the very middle of the storage tank from the time we connected the solar collector and began transferring heat to the tank.
Below are a set of temperature graphs in the months of March and April. The nice high curves occurred on sunny days. This also represents good heat transfer into the storage tank. Jagged red and blue lines represent partly sunny, mostly cloudy days or rainy days.
More data graphs can be created by clicking here.