A solar water heater is a way of harnessing solar energy to raise the temperature of the water. This technology, taking advantage of the sun's energy, can help you save on gas or electricity bills and contribute to caring for the environment.
Before choosing which solar water heater fits better with our needs, we need to know what they are, how they work and the differences ot the different types these systems.
What is a solar water heater?
solar water heaters are an efficient and ecological way of harnessing the sun's energy to heat water. It is a simple system consisting of a series of tubes or solar panels placed in a place where they directly receive the sun's rays.
The water circulates inside and heats up because the sun's heat increases its temperature.
A solar heater is made up of two main parts:
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Absorber plates: they capture solar radiation and transfers it to a liquid.
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A storage tank: it is a thermally insulated stainless steel tank where hot water is stored.
Types of solar water heaters: which one is best?
There are different types of solar heaters, from the most straightforward and cheapest to the most complex and expensive. In all of them, their function is to take advantage of solar energy to heat water, but each has a different efficiency and cost. The choice of each of them also depends on the desired temperature of the water.
Below are the three main types of solar water heaters:
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Flat plate collectors: they look like PV panels for power generating. However, inside, the place to contain solar cells, they have a coil through which cold water circulates that is exposed to the sun, whose radiation heats the contained water. With flat heaters, you can reach temperatures between 30 and 70 degrees Celsius.
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Evacuated tube collectors: This solar water heater comprises different glass tubes. Inside of each tube there is a cooper tube where the water circulates. These heaters are slightly more efficient but are more fragile. With them, temperatures between 50° and 190°C can be reached.
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Concentration solar heaters: they are used mainly in industry. They are designed with a concave shape to concentrate solar radiation at a certain point. They are very efficient and usually incorporate solar trackers for greater efficiency and can reach temperatures of up to 4000ºC.
Uses and applications of a solar water heater
solar water heaters, also known as solar hot water systems, are devices that use energy from the Sun to heat water. These systems can heat water for showers, laundry, or household appliances, among others.
This technology is widespread in sports facilities, hotels, and hospitals where hot water consumption is very high, and there are large surfaces to install solar collectors.
Concentrating solar water heaters are also used in the industrial sector. This type of heater is used to obtain temperatures up to 4000 degrees Celsius.
How does a solar water heater work?
The solar collector absorbs solar radiation and transfers its energy to the fluid flowing through it. Depending on the type of heater, the operation varies slightly, but the principle of operation is the same:
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Introduction of cold water to the solar water heater
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The water is heated as it circulates through the heater ducts exposed to solar radiation.
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The outgoing hot water is stored in a solar accumulator, which is a thermally insulated water tank.
In many cases, the tank is located just above the heater, so the hot water rises to the tank due to the difference in density. This system is called the thermosiphon effect. On the other hand, you can also circulate the water to the tank through a water pump.
Some solar water heaters use a heat transfer fluid to capture solar radiation, and then it goes through a heat exchanger to transfer its thermal energy to the water. These systems are more complex but more efficient.
Advantages of solar water heaters
Here are some of the main advantages of solar water heaters:
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solar water heaters are very efficient.
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Solar energy is a renewable and clean energy source. Therefore, solar water heaters do not produce any type of pollution.
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They are eco-friendly because by not using fossil fuels to operate, they do not emit carbon dioxide or other harmful substances into the atmosphere.
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Solar heaters can help reduce the electricity bill due we won’t use electric water heaters no longer. Although the initial cost is hight, in the long term it is compensated because we do not need electricity.
Disadvantages of solar water heaters
"solar water heaters are not a panacea for everyone's climate": It is true that in many parts of the world, solar heaters can be a great option to address climate change. However, in other places, such as southern Europe, where the climate is colder, solar heaters are not the best option. In fact, in some places they can even make things worse.
