A Solar water heater is also known as ‘solar thermal system’. This device is used for energy dependence as most of our energy is generated from the burning of fossil fuels because of which wide array of environmental issues occur. So, why risk our environment when we can use the sun’s energy which freely falls on Earth?
To utilize solar energy, simple equipment is required to capture the heat of the sun. Solar water systems capture this free energy to heat the water. The heated water can be used for a plethora of purposes such as bathing, cleaning, washing etc. Installing solar water heater provides unlimited clean energy and reduces electricity costs.
Working Principle of Solar Water Heater
The working principle of solar water heater is very simple. The device has collectors which absorb the radiations of sun and converts it into heat. Then, with the help of circulating pumps, this heat is passed to a water tank.
Thermal regulators trigger this exchange only when the collector is hotter than the water inside the tank. In this process, the hot water moves upwards due to its low density and due to gravity head, the cold water with higher density moves down from the water tank.
Generally, collectors are arranged in a series-parallel combination. This helps to get a huge quantity of hot water. At midday, during the summer season, the efficiency of these collectors is at its highest. In addition, the solar water system works great in other seasons as well.
When the sunlight is insufficient, the water in the tanks is pre-heated and then a backup system brings the water to the needed temperature. This way, the solar water heater working is continuous and generates hot water throughout the year.
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Types of Solar Water Heaters
There are different types of solar water heaters which includes the open-loop and the closed-loop systems. The different types of solar water heaters include:
- Drainback Solar Water Heating System:It uses distilled water as the heat transfer fluid. It acts as the medium and flows through the collector loop. The water flows through the collectors with the help of the pump. Drainback Solar Water Heating System is a non-pressurized system. The water flows to the heat exchanger and the storage tank under gravity.The system turns off when the pumps are off. It also has a setting which turns off the system when the water in the storage tank is too hot. Drainback Solar Water Heating System needs installation of the large piping system. However, it is more convenient as it does not need any check valves, pressure gauge, air vents etc.
- Active Open Loop Solar Water Heating System: This is a simple and cheap system which works on the principle of heat transfer through water under standard pressure. The system has a temperature controller at the base of the storage tank.When the water in the storage tank is cold, the differential controller activates the circulating pump. This draws the water from the storage tank to the solar collector where it gets heated up and returns to the top of the tank. Active Open Loop Solar Water Heating System delivers high performance due to low heat loss.
- Passive Solar Water Heating System: It needs an installation on the rooftop which also needs storage tank on the top. The system consists of the collector which takes up the cold water provided by the city supplier. In this collector, the water gets heated.The heated water flows to the storage tank where the water remains for the rest of the day until utilized. The chances of heat loss are more during this storage period. The thermosyphon system is a variation of this system which uses an insulated tank for storage of the heated water.
- Active Closed Loop Solar Water Heating System: The water heating system makes the use of the heat-transfer fluid (HTF) that flows through the heat exchanger and collector. This HTF is non-toxic in nature and help to transfer the heat to the water stored in the tanks. In the majority of the systems, glycol is the HTF which needs replacement every 3-10 years. However, this system is a little complex as the collector remains constantly under pressure.
- Evacuated-Tube Solar Collectors: The system has transparent glass tubes arranged parallel to each other. These tubes have an inner metal absorber tube with a fin. The surface of the fin has a coat which helps to absorb the solar energy. This is the commonly used system for the commercial purpose. The newer modification of this system has tempered glass cover plates. These plates help to enhance the durability of the heaters.
Uses of Solar Water Heater
There are many different purposes for which the solar water heater is the best available option. The different uses of solar water heater include:
- Domestic Use: The solar water heater has an application in domestic use for heating the water in apartments, bungalows, and flats.
- Commercial Use: The solar heaters are commercially used in places like the hostels, hospitals, hotels, dormitories, etc.
- Industrial Use: Many of the industries use these solar water heaters. The industries which need hot water for different purposes like washing, preheating or even different processes have this system.
Construction of Solar Water Heater
Construction of solar water heater is simple. The important parts of a solar water heater include a solar collector, heat transfer system, the heat transfer fluid, storage tank, pressure valve, piping, etc.
- Solar Collector: This is the part of the solar heater which helps to trap the sun’s energy and convert it into heat. Generally, it consists of a metal plate which is black in color and helps to absorb maximum heat. There are pipes below this plate which contain the fluid that gets heated. All these are then connected to the metal plate. The fluid runs through these pipes and gets heated.
- Storage Tank: The storage tank may or may not have the insulation. This helps in storage of water heated by heat transfer process. It has an inlet for the cold water at its base and the outlet for the heated water.
There are pipes below this plate which contain the fluid that gets heated. All these are then connected to the metal plate. The heat transfer fluid runs through these pipes and gets heated. This fluid then transfers the heat to the water. The tank houses the heat transfer system.
- Heat Transfer System: This system has the tubing which carries the heat transfer fluid. This fluid flows through the solar collector and gets heated up. The heated fluid then flows through the pipes to the heat transfer system within the storage tank.
- Pressure Valve and Air Vent: The storage tank also has a pressure valve and a vent. The pressure valve regulates the pressure within the tank and helps in air escape, in case of overpressure caused by steam or air.
Working of The Solar Water Heater
Solar Water Heater Working is not complex. The heat transfer system within the storage tank helps to heat the cooler water which is present at the base of the tank. The heat transfer process takes place and the water in the tank gets heated. This heated water moves upward in the tank and is ready for use. Fresh cool water enters the tank through the cold water inlet at the base.
If you are thinking about how to make a solar water heater, then gather all solar water heater information and build your own for conserving energy and to enjoy financial aids.