SOLAR+HEATERS+-+Sapphira

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__**How do they Work?** __

Solar water heating systems include storage tanks and solar collectors. There are two types of solar water heating systems: active, which have circulating pumps and controls, and passive, which don't. Passive solar water heating systems are typically less expensive than active systems, but they're usually not as efficient. However, passive systems can be more reliable and may last longer.

__There are two types of active solar water heating systems:__
 * Direct circulation systems**:** Pumps circulate household water through the collectors and into the home. They work well in climates where it rarely freezes.
 * Indirect circulation systems**:** Pumps circulate a non-freezing, heat-transfer fluid [eg: Silicone - it has a low freezing point] through the collectors and a [|heat exchanger] . This heats the water that then flows into the home. They are popular in climates prone to freezing temperatures.

__There are two basic types of passive systems:__    > __**Some diagrams to illustrate this:**__ >  >
 * Integral collector-storage passive systems: These work best in areas where temperatures rarely fall below freezing. They also work well in households with significant daytime and evening hot-water needs.
 * Thermosyphon systems**:** Water flows through the system when warm water rises as cooler water sinks. The collector must be installed below the storage tank so that warm water will rise into the tank. These systems are reliable, but contractors must pay careful attention to the roof design because of the heavy storage tank. They are usually more expensive than integral collector-storage passive systems.

__Energy Transfer Process - __ > "The solar collector is mounted facing south. As the sunlight passes through the collector’s glazing, it strikes an absorbing material which converts the sunlight into heat, and the glazing prevents the heat from escaping. The temperature inside a glazed solar collector on your roof can easily reach 150°C when there is no heat transfer fluid flowing through it. > > The two most common types of solar collectors used in solar water heaters are glazed flat plate and evacuated tube collectors. A glazed flat plate collector consists of a shallow rectangular box with a transparent glass “window” covering a flat black plate. The black plate is attached to a series of parallel tubes or one serpentine tube through which air, water, or other heat transfer fluids pass. > > An evacuated tube collector consists of several individual glass tubes, each containing a black metal pipe through which the heat transfer fluid passes. The space between the pipe and the glass tube is “evacuated,” so the air is removed." - > > Source: http://www.yogisolar.com/how_does_a_solar_water_heater_work.html



**__International Examples + Facts and Figures__** <span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 21px; line-height: 31px;">
 * SWH = Solar Water Heaters

From this table, we can see that Solar water heaters installed in South Africa has the fastest payback period from the cost of installation, while SWHs in the United States take the longest.

<span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 21px; line-height: 31px;">**__Evaluation__**

Advantages: -<span style="color: #555555; font-family: Verdana,'BitStream vera Sans',Helvetica,sans-serif; font-size: 12px; line-height: 17px;">Solar energy is clean, stable and does not emit carbon dioxide, sulfur dioxide and other harmful gases, which are usually electrical generation does. So, it does not contribute to global warming, acid rain or smog. <span style="color: #555555; font-family: Verdana,'BitStream vera Sans',Helvetica,sans-serif; font-size: 12px; line-height: 17px;">-Solar energy does not need fuel, thus saving us money <span style="color: #555555; font-family: Verdana,'BitStream vera Sans',Helvetica,sans-serif; font-size: 12px; line-height: 17px;">-No costs incurred after the initial cost is controlled, it is virtually maintenance free. And its easy expansion, as well as the solar panels may be necessary to add any family or machine. <span style="color: #555555; font-family: Verdana,'BitStream vera Sans',Helvetica,sans-serif; font-size: 12px; line-height: 17px;">-Since solar energy can work completely independently, it does not require any connections or anything that can be used effectively and easily anywhere. The system can be set up anywhere, in remote locations as well. So, these places can rely on solar energy, even if the art does not reach them. So its very pragmatic & cost-effective for the new site.

Disadvantages: <span style="color: #555555; font-family: Verdana,'BitStream vera Sans',Helvetica,sans-serif; font-size: 12px; line-height: 17px;">-The starting price is very high. Tools for installation costs can be expensive, usually due to high expensive semiconductor materials used to build solar power system. <span style="color: #555555; font-family: Verdana,'BitStream vera Sans',Helvetica,sans-serif; font-size: 12px; line-height: 17px;">-may not be available in case of bad weather conditions, or easily influenced by the presence of water vapor, pollution, etc <span style="color: #555555; font-family: Verdana,'BitStream vera Sans',Helvetica,sans-serif; font-size: 12px; line-height: 17px;">-Require a large area for installation to achieve a good level of performance. <span style="color: #555555; font-family: Verdana,'BitStream vera Sans',Helvetica,sans-serif; font-size: 12px; line-height: 17px;">-Looks unattractive; Visually polluting the landscape

To conclude, Solar Water heaters are effective if they're installed in regions with lots of sunshine exposure. If so, the money saved eventually overcomes the installation cost, and will provide free heating for years to come. Since it uses renewable energy, it does not contribute to greenhouse gases that causes global warming.

If you're feeling ambitious, you can make your own solar heater [|Here!]

__**Sources**__
 * http://www.energysavers.gov/ **
 * http://www.yogisolar.com/ **
 * http://en.wikipedia.org/ **