Solar Water Heating
Hot water is a necessity of modern living. We use hot water for cleaning, cooking and bathing. Traditionally water is heated with an electric immersion heating element. This method is extremely energy intensive and has high inefficiency associated with it. Using solar water heating to augment or replace this system can decrease your energy bills significantly.
Solar thermal heating uses collectors similar to solar panels that sit out in the sun, and are either roof or ground mounted. These collectors can be as simple as a box with a glass top and copper pipe running through them to complex evacuated tube models where the water pipes are enclosed in vacuum tubes. Each of these methods has different efficiency and heating characteristics.
Innovative uses of these systems include swimming pool heating, and Laundromat use. Solar water heating of swimming pools is quite possibly one of the most efficient uses of the technology. Pools have such a large volume of water that when they are heated electrically, they use massive amounts of energy. This can be mitigated substantially by using solar water heating.
Two different technologies are used to move water through the system. Passive systems with no pumps use convection to move water and heat through the solar water heating system. Active systems have pumps which increase the heating efficiency of the system, however they do consume electricity and many people forget this when they are installing a solar water heating system. When determining the overall efficiency of the system, this must be taken into account.
In order to further take advantage of the energy imparted on the earth by the sun, some solar water heating systems use parabolic mirrors to further concentrate the sunlight and heating effect and thus can heat water to higher temperatures. Once heated, water can be stored in outdoor tanks or insulated indoor tanks similar to existing domestic hot water systems.
Solar water heating can also be used to provide heat for radiant floor heating systems. This means that rather than having electric elements provide the heat to the floor, hot water is run through a series of tubes under the floor. When energy is converted from thermal to electric to mechanical, losses are present. Direct solar water heating removes these conversions and thus decreases the amount of losses associated with the heating systems.
Hybrid photovoltaic (solar electric) and solar thermal systems can be combined so that the system can produce both electricity and hot water from co-located panels. In order for this to be efficient, the surface area of each part of the system must not overlap, because covering either of the systems will reduce its efficiency.