Eviath Boilers

How to choose a solar water heater

Eviath — Wed, 14 Jul 2021 00:00:25 +0000

How to choose a solar water heater?

Solar water heaters are divided into different types depending on their function. Which they are and what are their differences we have discussed in a previous article which can be found here. In terms of how you can distinguish the quality of a solar water heater, this article is here to help you.

Let’s start with the basics, the sheet in the inner tank must be 2.5 mm – 3.0 mm thick, to ensure that the tank can withstand high water pressures. In the closed circuit, the antifreeze liquid must be protected by a jacket to ensure the operation of the solar water heater even in frosty periods as well as to protect the collectors from getting clogged from the salts.

One of the most important things you have to notice to understand if the quality of the tank is good is the enameling inside. Enameling is the glass surface created by melting and joining the enamel onto a steel surface. Enamel is a mixture of inorganic silicates which are perfectly healthy and ecological (does not contain hazardous chemicals), water-soluble, and can be baked at high temperatures (> 850C °).

Most recommended is the liquid enamel due to its special elasticity and the high resistance it has in hard waters. With the liquid enamel, the tank is protected from any cracks that may occur due to contraction and expansion, especially during the winter months when there are large fluctuations in temperature.

Also, to make sure that the water will remain hot and at very low temperatures, it is necessary the solar water heater that we will choose to have for thermal insulation polyurethane of high density & thickness (at least 45-50 mm), which due to its composition creates insulation without cracks and joints.

These are some of the most important features that a solar water heater should have in order to be sure of its quality and durability even in adverse conditions.

If this information is not enough to help you decide what solar water heater matches your needs best, we remain at your disposal to help you with any inquires!

Why buy a solar water heater?

Eviath — Wed, 14 Jul 2021 00:00:23 +0000

Why should I buy a solar water heater?

Buying a solar water heater is an investment worth making, it is certain that you will profit from it. Solar water heaters began to be produced & used around 1973 during the oil crisis & the first solar water heater in Greece was officially launched on the market in 1974. Greece is one of the leading manufacturers of solar water heaters for years & occupies the fifth place in the world ranking showing the square meters covered by solar panels per inhabitant.

Money-saving.

Saving money starts from the first day of the installation. In countries with high levels of sunshine, it is estimated that the solar water heater pays off in 2-3 years, while in countries with average sunshine in about 4-5 years. As our boilers have a lifespan of over 20 years this cost is reimbursed many times during these years. Also, depending on the consumption, you save about 40% to 80% of energy per month, and consequently, your electricity bill is significantly reduced. Finally, even the maintenance of the solar water heater requires little money.

Energy-saving.

Solar water heaters are the cleanest system that uses renewable energy sources as it does not emit any carbon dioxide during operation. By using a solar water heater we achieve about 40% – 80% in energy savings as it is estimated that about 10-15% of the daily energy is consumed for water heating. According to the Association of Solar Energy Industries, in Greece, there are 2.8 GWth of installed capacity with most systems being solar water heaters, which prevent the emission of 2 million tonnes of carbon dioxide each year while over 4 billion kilowatt-hours of electricity and about 240,000 tonnes of oil are wasted just to heat water in our buildings. In addition, solar water heaters play a role in reducing water pollution as power plants release mercury and other toxic heavy metals into them.

Easy installation & maintenance.

Installing a solar system is a relatively simple process as the necessary instructions are provided for the assembly of the base, the collectors as well as the boiler. However, is required to follow the instructions. The maintenance of the solar water heater, as well as any device, is necessary but it is not needed too often. It is recommended to service every 2 years to change the anode, replenish the antifreeze liquid, and additionally clean the inside of the tank from accumulated salts and germs. This way you save money again as the efficiency of the solar water heater is ensured and its life is extended.

How does a solar water heater work?

Eviath — Wed, 14 Jul 2021 00:00:16 +0000

The operation of the solar water heater varies depending on its type & water circulation. If the boiler is mounted higher than the collectors then it operates according to the natural flow, where the hot water goes to the boiler as the mass of the hot water is lighter and therefore tends to rise above the cold water which mass is heavier.If the boiler is mounted lower than the collectors, a pump (forced circulation) is needed.

Each solar water heater consists of 2 basic parts. The collector where it collects energy from the sun’s rays & the boiler where the water is being stored.

Collector:

The solar panel consists of the absorber plate (which is always dark in color), the crystal that surrounds the absorber plate, and the pipes into which the water flows. Its operation is based essentially on the greenhouse effect. As the sun’s rays fall on the crystal and penetrate it, they end up in the absorption plate where due to its dark color and its material it heats up. This temperature then is trapped between the crystal (Greenhouse effect), maintains & transfer from the plate to the pipes where the water is heated, and then stored in the boiler.

About the kind, the boiler can be double energy, triple energy, or heat pump boiler as well as either open or closed circuit.

Boiler types are divided into categories:

A) Depending on how the water is heated.

Open or closed circuit boiler.

In an open circuit boiler, the water flows through a collector, is heated directly, and returns for storage in the boiler as well as use. While in the closed-circuit boiler the water remains stored in the boiler while the energy (heat) is transferred through a closed circuit in which there is different water combined with antifreeze liquid circulating through the collector, heats up and thus indirectly transfers the heat to the stored water.

B) Depending on the energy sources available for connection.

Double or triple energy boiler.

In the double energy boiler, the available sources are solar energy & electricity. Inside the boiler, there is an electrical resistance thanks to which it is possible to turn on the solar water heater using electricity and heat the water, for example during the winter months when the sunshine is less.

The above applies also to the triple energy boiler, however, there is also the possibility of connection to the central heating of the house thanks to the coil inside. Τhis coil circulates the hot water produced by the central heating boiler and then heats the water inside the boiler.

Heat Pump Boiler

Ιn heat pump boilers except for the solar & electrical power there is also the possibility for connection with the heat pump. Heat pump boilers contain large surface coils. This is required because heat pumps operate at a lower temperature than boilers so we use them so that energy can be exchanged at these low temperatures as well.

How many liters should my solar water heater be?

Eviath — Wed, 14 Jul 2021 00:00:03 +0000

How many liters should my solar water heater be?

The choice of size of a solar water heater depends mainly on the number of people living in the house as well as on the use of hot water they make. It is estimated that each person consumes about 40L of hot water in every shower, however, this number is indicative and is not addressed to all consumers. Therefore, it is true that the more people there are, the more liters they need.

Our 120L solar water heater has a capacity of 114 liters and can serve 2 to 3 people.
150L solar water heater has a capacity of 146L and can serve 3-4 people.
200L solar water heater can serve 4 to 5 people
250L water heater with a capacity of 244L can accommodate up to 6 people.
While our 300L solar water heaters can serve about 7-8 people.

We need to clarify that these numbers are indicative, as all people use different amounts of hot water. We must also keep in mind that the hot water in a house is not only used for bathing & showering but also for washing dishes, washing machine, etc.

So when it comes to choosing the size of your solar water heater you have many options and factors to consider. We hope this article helps you make your choice and if you have more questions we are at your service in order to help you make the right choice.

Usage of solar water heater worldwide

Eviath — Wed, 14 Jul 2021 00:00:00 +0000

Usage of solar water heaters worldwide.

Solar water heaters since their introduction to the market in the ‘70s, have managed to establish themselves worldwide. In some countries of the world, the use of solar water heaters differs significantly from others as for its operation is necessary that in the country there is enough sunshine.

According to the Technical Chamber of Greece, the total installed surface of collectors for water heating in the EU is estimated with a capacity of up to 2.9GW. Internationally, Cyprus has the highest total thermal power per capita with 554,0 kW per 1000 inhabitants, followed by Israel with 390.9 kW , the islands of Barbados with 323.9 kW, Austria with 314,5kW, and fifth comes Greece with 265.8kW per 1000 inhabitants respectively.

Greece was one of the first countries in the European Union that manufactured solar water heaters as well as one of the biggest. It is estimated that in Greece without solar water heaters it would be necessary to build and operate another thermal power unit with a capacity of at least 600MWth. In our country, there is still a large margin for the adoption of solar water heaters. According to the Hellenic Association of Solar Energy Industries, in Cyprus, where similar environmental and weather conditions prevail, approximately 0.94m² solar collector surface corresponds per inhabitant while in Greece only 0.32m²/inhabitant. Most of these applications are for home use while only 2% are for hotels, industries, and hospitals. That’s how we came to the conclusion that there is a lot of room for more solar water heaters to be installed especially in the industrial sector.

In the US more than 1.5 million homes & businesses today use solar water heating, representing a capacity of over 1000MW of thermal energy production. Another 400MW is likely to be installed in the next 3-5 years according to the US Department of Energy. Assuming that 40% of existing homes in the United States have adequate access to sunlight, it is estimated that a further 29 million solar systems could be installed.

Many countries have made the installation of a solar water heater system mandatory for new residential buildings, while others, such as Greece, subsidize their purchase.

Taking into account these data from different parts of the world, it is obvious that there is still a great potential for development in the field of solar water heaters.