Other Solar Technologies

Solar Cooling

Instead of heating, heat energy captured in the sunlight can be used to produce cooling. Solar cooling can be done by coupling a solar water heating system with an absorption chiller or an adsorption chiller.
 

Solar Absorption Cooling

In an absorption chiller, heat is used to evaporate a refrigerant under pressure from an absorbent/refrigerant mixture. The two most common refrigerant/absorbent mixtures are water/lithium bromide and ammonia/water. Condensation of the evaporated refrigerant provides the cooling effect. Electricity is required to keep the refrigerant running, but the electricity consumption is relatively small compared to conventional electric chillers. Solar absorption cooling systems use hot water from solar thermal collectors as the heat source to evaporate the refrigerant. They are designed to meet the air conditioning load of a building during sunny periods.
 

Solar Adsorption Cooling

Solar cooling can also be done by matching a solar water heating system with an adsorption chiller. An adsorption chiller contains water as a refrigerant and silica gel as an adsorbent. The evaporator section cools the chilled water through the action of the refrigerant (water) being evaporated by adsorption of the silica gel in one of the two adsorbent chambers. For a solar adsorption cooling system, the hot water from solar water heating system regenerates the silica gel in the second of the two adsorbent chambers. The water vapor released from the silica gel by the hot water will be condensed in the condenser section which is cooled by the cooling water, such as from a cooling tower. Electricity is required for the controls and for the pumps. But again, the electricity consumption is low compared to conventional electric chillers.