Clean Tech 101

Solar Hot Water System - Using the Sun's Energy to Heat Water

How Does Solar Hot Water Systems Work?
Solar Water Heating for Buildings
Active Solar Hot Water Systems
Passive Solar Hot Water Systems

Using the energy from the sun to heat water reduces household hot water bills by at least 65% per year. This could accumulate to savings of thousands of dollars over the lifetime of the solar hot water system. Solar hot water system also helps the environment by reducing the amount of greenhouse gas emitted into the atmosphere.

How Does Solar Hot Water Systems Work?

In a solar hot water system, the sun's energy is used to directly heat water. This is similar to water in a hose left in the backyard and gets heated up during a sunny day. Water is heated as it travels through flat, glazed panels known as solar collectors, which are normally situated on the roof of a house. The heated water is then stored in an insulated storage tank. An auxiliary heater may be used to increase the water temperature when there is a limited supply of solar energy to meet the hot water requirements.

Solar Water Heating for Buildings

The majority of solar water-heating systems for buildings consists of two main components:

  • A solar collector - Most common type are the flat-plate collector, and
  • A storage tank

Solar water heating systems can be categorized as active or passive solar water heater systems.

Active Solar Hot Water Systems

Active solar water heaters use controllers and electric pumps to circulate water through the solar collectors. These are the two types of active solar water-heating systems: direct-circulation systems and indirect-circulation systems.

Direct-circulation systems employ pumps to circulate pressurized potable water directly through the collectors.

Indirect-circulation systems pump heat-transfer fluids instead of water through solar collectors, where the heat exchangers transfer the heat from the fluid to the potable water. The two most common indirect systems are antifreeze and drainback systems.

(Source: EERE)

Passive Solar Hot Water Systems

Passive solar water heaters use gravity and the likelihood for water to circulate as the water is heated. Since passive solar water heaters contain no electrical components, it is generally easier to maintain and more reliable than active systems. The two most popular types of passive systems are integral-collector storage systems and thermosyphon systems.

(Source: EERE)

Source: AZoCleantech
Last update 20th February 2008

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