Solar Hot Water System
From Swikipedia
Introduction
A Solar Water Heater (SWH) is a device that uses solar energy to heat water. It is an energy efficient hot water system.
Solar heating systems are generally composed of solar thermal collectors, a fluid system to move the heat from the collector to its point of usage. The system may use electricity for pumping the fluid, and have a reservoir or tank for heat storage and subsequent use. The systems may be used to heat water for a wide variety of uses, including home, business and industrial uses. Heating swimming pools, underfloor heating or energy input for space heating or cooling are more specific examples.
Brief Description
Types of solar hot water systems:
Solar hot water systems vary a lot. Some are very simple, others much more complex. Some are specially designed for moderate and hot climates and others for colder climates.
The several types of solar hot water systems are:
o Thermosyphon solar systems:
They are simple and reliable and the most common solar water heaters used worldwide. A thermosyphon solar system consists of a solar collector and a cylinder located immediately above it.
o Solar open-active heating systems (moderate and hot climates):
They are simple solar water heating systems with a pump. They provide wider possibilities in terms of location of the collector or the tanks (the collectors do not have to be placed on the roof). Besides this system can also solve problems with extreme temperatures (risk of freezing pipes, too hot water and the danger of burst pipe-work).
o ICS Batch solar systems (a basic system for moderate climates):
In its most simple version, a batch heater is just a water tank within a glazed box, placed in a sun facing surface (facing the south in the northern hemisphere, or facing the north in the southern hemisphere). Batch solar collectors are cheap options, with a low maintenance (in favorable temperatures). And they are a reliable technology when applied in appropriate climate conditions. The system doesn’t demand pumps or specific tanks: batch system just pre-heats the water for existing water heater.
o Drainback systems (cold climates):
Drainback systems use a pump to circulate water in the collector loop, which drops into a reservoir tank when the pump stops. They also use a differential controller to start the pump (or the pumps) and to route the distilled water into the system. This process begins whenever the sensors attached to the collector detect useful sunlight available (which happens when the temperature in the collector is higher than the temperature of the water at the bottom of the storage tank).
o Anti-freezing pressurized systems (cold climates):
Anti-freezing solar heating systems are relatively complex systems. They involve a solar collector, an expansion tank and a storage-backup tank, a pump, a heat-exchanger, a differential controller and some valves and sensors.
Benefits of Using Solar Hot Water System:
Solar Water Heater has several advantages over conventional water heating systems. They are:
o They save electrical energy
o Save interior space (because they are usually located on rooftops)
o Eliminate the risk of accidents in bathrooms due to electrical water heating equipment
o They require little or no care and attention while providing hot water for about 300 days in a year in most parts of India.
o For society at large, they reduce the need for fossil fuels for electrical generation and for fuels such as firewood, coal, furnace oil, etc, that are used in domestic, commercial and industrial boilers. Thereby, they also reduce degradation of the environment.
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