Provide a cylindrical thermal energy storage solar preheat tank with a storage capacity of at least 1.5 gallons per square foot of collector area.  Insulate each tank with fiberglass or foam with a loss coefficient of not more than 0.5 W/m2C.  Protect the insulation by a PVC or steel jacket.  Provide a tank rated at 100 lb/in2 at 190 degrees Fahrenheit.  Provide the interior of each tank with glass lining for potable service.