Design and Technology – Energy and control systems | e-Consult

The solar water heater system involves a series of energy conversions. The primary energy source is solar radiation, which is a form of radiant energy. This energy is converted into thermal energy when absorbed by the absorber material (typically a dark-colored panel) within the solar collector. The absorber material heats up, transferring thermal energy to a fluid (water or a heat transfer fluid) circulating within the collector.

The heated fluid then transports the thermal energy to a storage tank. Within the tank, the thermal energy is transferred to the water stored inside, raising its temperature. The hot water now possesses both thermal energy and potential energy (due to its height in the tank). When the tap is opened, the thermal energy in the hot water is converted into kinetic energy as the water flows through the pipes. This kinetic energy is what delivers the hot water to the user.

Energy losses occur at each stage of this conversion.

• Radiation losses: Some solar radiation is reflected by the collector surface.

• Convection losses: Heat can be lost from the collector to the surrounding air.

• Conduction losses: Heat can be lost from the collector to the storage tank.

• Pipe insulation losses: Heat can be lost from the storage tank through poorly insulated pipes.

Efficient design considerations, such as using insulated panels and tanks, minimizing pipe lengths, and using reflective surfaces, are crucial to reduce these losses and improve the overall efficiency of the system.