The storage tank is typically installed in the basement, garage or utility room and is well insulated. Sensors are used to monitor the temperatures of the anti-freeze solution in the system. A differential control unit attached to the sensors determines when the circulating pump should be activated. If the temperature at the collector is 20 degrees F greater than the temperature at the bottom of the storage tank the solution in the system is circulated in the closed loop. In this way the water in the system is always being heated when the Sun is shining.
Indirect systems are closed loop systems.
There is no contact between the anti-freeze solution and the potable water in the system. A PV panel converts sunlight into electricity. This electricity can be used to power the electrical components in the system. The PV panel or PV system and the components are matched in the design process to optimize overall system performance. The basic components of Indirect Systems are listed below.