An Overview of a Solar Water Heater System

An Overview of a Solar Water Heater System
July 15, 2011 Lorelie

Water heaters are without doubt an essential part of any home especially if the home is located on cold regions. If you want to take a shower, want to wash your hands, or when washing laundry and kitchenware, there are times that hot water is far better to use as it does not only provide more comfort, but it is also more convenient to use. However, the use of hot water does have its drawbacks, and this is mostly exhibited in the monthly utility bills. This is because in order to heat water, you will need some sort of energy to heat it with such as electricity or gasoline. The use of such energy resources will surely add expenses to the household, not to mention the upkeep they sometimes need.

The truth is not all water heating equipments can add to the monthly utility expenses. Solar water heaters use the sun’s energy to generate heat, which of course is not only free, but is also a clean and renewable form of energy. Solar water heater systems don’t just heat water, they are also capable of heating living spaces, floors, towels, pools, and spas.

Solar water heater systems are very cost effective equipments and can provide up to 70% of the hot water needs of a typical household and the return of investment can occur in just 5 to 7 years.  Basically, a solar water heater system works by using solar energy through its solar panels or collector to heat the water, and storing the heated water onto insulated storage tanks. There are some systems or models however that simply preheat water and are used in conjunction with tankless water heaters.

A solar water heater system generally works by circulating glycol through the system – between the solar collector and the heat exchanger. The heat exchanger is typically placed inside a specialized solar hot water tank or adjacent to a more traditional hot water tank. Nevertheless, both types make use of hot glycol which flows through the heat exchanger which heats the water inside the tank. This tank is typically connected to the water supply of the household, such as on showers and sinks. If the system will be used for spaced heating, the need for a second heat exchanger is a must to provide heating for radiators, floors, and heat pumps.

There are generally two types of solar water heaters – Active and Passive. Active solar water heater systems have controls over the circulating pumps, while passive systems do not. They are more simpler in design and are more reliable.

 

Active Solar Water Heating Systems:
- Indirect Circulation System – these systems are ideal for climates with freezing temperature. They use heat-transfer fluid and pumps to circulate the fluid on the collector and heat exchanger. Upon reaching that point, the heated fluid goes through heating coils towards the storage tank.
- Direct Circulation System – this is a more direct approach as it eliminates the use of a heat-transfer fluid. The water here circulates directly through the collector and heat exchanger.

Passive Solar Water Heating System:
- Thermosyphon Models – this model has a storage tank with a collector situated at its bottom. This heat water at the bottom. The heated water rises from tank while the cold water goes to the bottom which will then be heated.
- Integral Collector-Storage Passive Models – these models are used in combination with instant water heaters.

There are actually several types of solar collectors – the evacuated-tube solar collector, the flat plate collector, and the integral collector storage.

- Evacuated-Tube Solar Collectors – this type of solar collector use an array of transparent glass tubes arranged in rows. These types of arrangements are found mostly on commercial systems but are also found on some homes. Within each glass tube is a metal absorber tube that has a fin.
- Flat-Plate Collectors – these are dark-colored plate absorbers that are under a glass or polymer cover.
- Integral Collector Storage – this type of collector use either black tubes or tanks that are enveloped in a glazed insulated box. Their purpose is for preheating cold water and passed onto more conventional water heaters.

When people think of solar collectors, or more commonly solar panels, they immediately think of photo-voltaic panels which are able to generate electricity using the light energy from the sun. Solar water heater systems are not able to generate electricity. Instead, of electricity, their solar panels generate heat. The heating capability of this type of solar system is beneficial as it can be used to heat water that can be used for showers, dishwashing, and laundry.

We all know that heat generation use a lot of energy. If you are heating water using electricity or gasoline, you will without doubt consume a lot of energy which in turn adds to your utility bill. However, if you replace this type of heating with solar heating, you will considerably save a lot of money.

Depending on their application, a solar water heating system will cost less and is more economical in the long run. In fact, they even require less space for collectors as compared to photo-voltaic systems.

The control of solar water heater systems vary, although they all have a series of sensors and pumps that control the glycol which circulates throughout the system. They have a heat sensor switch that can be adjusted as needed. This switch controls the glycol pump when the temperature is higher at the solar collector than its return temperature. It will circulate the glycol from the collector to the heat exchanger and will continue to do so until it reaches its predetermined temperature. It will then automatically switch off once its preset temperature has been reached. If the temperature falls below the preset minimum temperature, the cycle will start again. Most solar water heater systems have a backup system. They are either connected to an electric heating element or a gas-fired heating system. This will help the household have hot water even when it is being used for prolonged periods, or when there is rain or thick clouds outside.

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