How Solar Water Heaters Work?
Solar water heater can be a cost effective solution to generate hot water at home, while making use of a natural free resource, the sun. The solar water heating systems basically include storage tanks and solar collectors. How these two combination work together to heat up and generate hot water at home?
In general, there are two types of solar water heating systems in the market: the active type, which has pumps to circular and control the heat flow; and the passive type, which without the pumps. You can choose to install one-tank system or two-tank system. The key different of extra one tank in two-tank system is the water will be preheated before it enters into the conventional water heater. While one-tank water heating system costs cheaper in set-up and installation, it may not fully utilize the solar power efficiency. For example, if the hot water is being used during the evening and depletes of storage tank of hot water, the system need to use the backup heating system generated from electric or gas to heat up the tank. On the next day, when there is sunshine, the tank is warm and the efficiency of using solar for heating is greatly diminished. Therefore, the two-tank solar water heating system will have higher efficiency to fully utilize the solar power to generate hot water with its preheated tank.
The solar water heating systems use solar thermal collectors to receive heat from the sun. There are 3 types of solar thermal collectors, which are commonly used in residential solar water heating systems:
1. Flat-plate collectors
Flat-plate collector is the key component in active solar heating systems. It best suits for application where the demand temperature is 30 degree to 70 degree such as the water heating systems used for winter months. The function of flat-plate collectors is to circulate fluid to a pre-set temperature.
2. Evacuated-tube solar collectors
This type of solar collectors is commonly used for commercial application or at home that requires a highly reliable source of hot water. It has parallel rows of transparent glass tubes and each tube consist of an outer tube which made from glass and metal absorber tube that is attached to a fin. The fin is coated with materials that is good at absorbing solar energy while inhibiting radioactive heat loss. Therefore, it provides very reliable source of hot water. But, the price of Evacuated-tube solar collectors is more expensive if you compare to other 2 types of solar collectors; that’s why it is more frequently used for commercial applications.
3. Integral collector-storage systems (ICS)
It is a batch system that featured one or more black tanks insulated in a glazed box. The cold water is preheats by the solar collectors and then go into the conventional backup water heater to provide a reliable source of hot water. This system works better in mild freeze climates as the pipes that are installed outside may get freeze in cold whether.
Summary
The solar water heating systems consist of combination of storage tanks and solar collectors that work together to generate hot water using the power from the sun.
Renewable energy from the sun and the wind are very cost effective energy sources, but the installation can be expensive, unless you do-it-yourself. Visit Dave Stilman at http://www.wind-solar-power.info to find the best renewable energy guide with step-by-step guide to build a solar power system or wind power system yourself at a minimum cost.
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