How to choose a solar water heater for your home?

The celestial body is the most powerful source of energy known to mankind. Sunlight can be converted into electrical and thermal energy. In this article, we will be interested in precisely the thermal energy, which we receive from the sun absolutely free of charge and it is inexhaustible. Devices such as solar water heaters convert the sun's energy into thermal energy. Factory devices have good performance and allow you to organize heating of a private house. There are craftsmen who make such devices on their own. Solar water heaters heat water free of charge to heat the home or for the boiler, where it already gives off heat to heat the water used for washing. Such devices are in demand among the owners of private houses and summer cottages. In this article, we will talk about the principle of operation of solar water heaters, their types, main manufacturers and prices.

Solar Water Heater Working Principle

First, let's figure out how solar water heaters work. We will consider the operation of such a device using the example of a factory model of a vacuum water heater. It heats up the water in winter without any problems. Performance in winter is of course lower than in summer. The design of the water heater is a battery, which consists of several glass tubes of quartz glass. Each such tube contains a copper tube painted black. These inner tubes contain the heating medium. A vacuum is created in the glass tubes so that there is no heat loss from the internal circuit. In addition, the vacuum protects the battery from environmental influences. All pipes are connected to a horizontal collector through which the coolant circulates. The vacuum tubes absorb solar energy and release it to the water.

Solar Water Heater Working Principle
This system functions as follows:

• The working liquid (the liquid does not have to be water) evaporates under the influence of sunlight, and the vapor rises to the top of the glass bulb;
• The steam comes into contact with water through the wall, which circulates through the collector. The steam gives off thermal energy, cools and turns into liquid again;
• Under the action of gravity, the liquid flows down and so the cycle is closed;
• The collector of the water heater is connected by means of pipelines to the indirect heating boiler. There, water is already heated, which circulates in the heating or water supply circuit. The coolant is circulated by a pump.

The quartz glass from which the vacuum tubes are made transmits ultraviolet waves. Ordinary glass holds them back. Thanks to the transmission of ultraviolet light, solar energy is absorbed when it is cloudy and during the winter season. It is very difficult to make such a design at home.

There are water heaters with a less complex operating principle. In gravity water heaters, heat energy is transferred without an intermediary. Usually, they have a coil (copper, aluminum) on a metal substrate or without it. The back wall of the case is lined with heat-insulating materials. The coil is connected to the storage tank by means of pipelines. The coil and plate (also called an absorber) are painted black for better absorption of sunlight. The top of the case is covered with glass, polycarbonate, etc. And also thorough insulation has been carried out to prevent precipitation, dirt, dust from falling.

Such a simplified water heater works effectively only in clear weather.But due to the simplicity of the design, such water heaters are most often made by hand. In addition, there is another option to get a water heater powered by free solar energy. Solar panels are installed that generate electricity. And this electricity runs a conventional water heater. Such a system can also work all year round.

Solar powered water heaters for home

A solar water heater is perhaps the most efficient, safest and most cost effective boiler. After all, such a heater is "powered" by free and inexhaustible solar energy, serving a hot water supply system designed for any volume and number of users.

Therefore, in this article we will consider the design of a typical solar water heater, as well as specific models of such equipment. Based on this information, you can buy a solar water heater suitable for servicing the hot water system or heating your particular home.

The first ever solar water heaters

The first solar water heater was developed back in 1767. It was invented by an ordinary resident of Switzerland ─ Horace Bnedict de Saussure. In his invention, he was able to achieve simply boiling water. But then it was already a success. And the Swiss inventor started selling his water heaters.

Horace Bnedict de Saussure
In 1953, the device was improved in Israel. Scientist Zvi Tavor even received an award for this from the country's prime minister. This simple water heating technology is still popular in our century.

Varieties of solar water heaters

Now let's talk about the types of solar water heaters. They are classified according to various design features.

For example, the following water heaters are distinguished by the type of coolant circulation:

• With natural circulation;
• With forced.

In the first case, water circulates due to its physical properties. When heated, it increases in volume, its density decreases. As a result, the liquid rises through the tubes, and cold water flows in its place. For natural circulation to pass, the reservoir must be on top of the collector, and this is not always convenient.

In the second case, the storage tank is installed in the basement, and forced circulation is provided by special pumps. With such an organization, oil can play the role of a heat carrier. It does this function very well.

Water heaters can be classified by collector design:

• Vacuum. The coolant is in a tube that is sealed in a vacuum flask. This bulb is made of quartz glass that transmits solar heat, as well as ultraviolet light. These are highly efficient designs where heat loss is minimal. If water is used as a heat carrier, then heating occurs to a boil. If there is oil there, then it can be heated up to 200-300 degrees. Almost all vacuum water heaters are factory-made and are quite expensive;
• Panel. The design is the simplest. The collector is painted black, housed in an insulated casing and hermetically sealed with glass, plastic, polycarbonate, etc. The efficiency is poor. This is because the fluid loses some of its heat as it passes through the manifold. These losses are usually quite significant. Panel solar water heaters are well suited for regions with high solar insolation.

Closed Loop Solar Water Heater

In addition, water heaters can be classified according to the type of circuit:

• Open loop. This design is used when organizing hot water supply to a residential building. The role of the coolant is water, which after heating no longer gets back into the collector. It is spent on household needs;
• One closed loop.It is used for heating a residential building. In this case, the coolant from the water heater is mixed with another liquid (possibly not water) that was heated in the main boiler. In a closed loop, the coolant, after heating, passes through the heating system and returns to the collector again;
• Two closed contours. Such water heaters are versatile and the most efficient. This system can be used to generate hot water or heating all year round. Having heated up in the collector, the coolant goes to the heat exchanger and transfers heat to the second circuit. And already the coolant in this second circuit is consumed as hot water or for heating the house.

The coolant can also be different. The most commonly used water, antifreeze, oil. You can also subdivide water heaters according to the general principle of operation into passive and active systems.

• Passive. Energy absorption and accumulation occur by themselves without any control mechanisms. Such systems are simple and do not require serious investments. For this you have to pay with uneven work and power surges. An example is the tank above the summer shower, which is painted black. This is usually the case for single-loop systems. Here, the receiving tank should be above the manifold;
• Active. There are no downsides to a passive water heater. Here solar energy is converted into thermal energy and is periodically transferred to a storage tank, boiler or directly to consumers. Stable operation is achieved thanks to the forced circulation system. This scheme works in systems with one and two circuits. In such systems, you can often see pumps, panels, gauges, etc.

Solar collector Summer cottage

"OPTON IMPEX" offers a wide range of innovative products manufactured under the ANDI Group trademark, both in China at our specially selected factories and under the supervision of our technical specialists who carry out periodic inspection control, and at factories in the European Union with a long tradition of quality.

• Solar water heaters for summer cottages series Dacha Economy model XF—II, Dacha-Lux model XFS—II. System without pressure for seasonal use.

If there is still no electricity and gas at the dacha, and heating the water presents a certain difficulty, the Dacha solar water heater easily solves this problem. It will provide you with hot water for taking a shower, washing dishes, heating a summer pool, watering plants and other household and household needs. The assembly and installation of this system does not require special knowledge and skills and usually takes 2-3 hours.

Solar collector for summer cottages price from 13 200 before 26 500 rub.

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• Solar collectors series Station wagon model CP—II Pressurized system for year-round use.

The main advantage of the Universal solar collector is the possibility of using it all year round in areas with a temperate climate and temperatures down to -35 ° C. Thanks to the use of Heat Pipe technology in the construction of vacuum tubes, the Universal water heater provides excellent results even on cloudy days. The collector's vacuum tubes are capable of absorbing the energy of infrared rays that pass through the clouds. Due to the insulating properties of vacuum, the influence of wind and low temperatures on the operation of evacuated pipes is negligible.

Solar collector Universal price from 40 500 before 65 000 rub.

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• Solar water heaters series Split system model SH for hot water supply and heating. Split solar system for hot water supply and heating.

Vacuum collectors with indirect heat transfer of solar energy to water. Also, such systems are called all-season or separate.The principle of operation of such collectors resembles the operation of a central heating installation. It is a closed system that can operate under water pressure. The system has low inertia, quick release to the operating mode and allows you to provide: Year-round - hot water supply; Seasonal heating with savings of traditional sources of thermal energy up to 70% (depending on the geographical latitude and climatic conditions).

Solar split system price from 74 200 before 375 000 rub.

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• Vacuum solar collector series Panel model SCH is part of the SH series split systems.

The SCH collector directly heats the heat carrier of the heat exchanger circuit, which transfers heat energy to the heat carrier of the main volume of the split system. The SCH vacuum solar collector is designed to reduce energy costs by integrating into existing (in operation) DHW and heating systems with circulation of a coolant, operating on traditional energy carriers, as well as for scaling, increasing the capacity of solar collector systems. Works effectively at temperatures up to -40 degrees.

Solar Collector Panel Price from 19 300 before 44 000 rub.

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Applications and installation requirements

So where are solar water heaters applied?

• Hot water supply of a private house;
• Heating;
• Heating of water for summer cottages;
• Hot water for the needs of agriculture and industry.

Solar water heater for home heating

It is important to take into account the installation recommendations, since the efficiency of the water heater will fully depend on this. Here are some of the recommendations of the experts:

• The place of installation can be the roof of the house, facade, balcony;
• The water heater panel must necessarily face south;
• When installing the panel, make the angle of inclination equal to the latitude of your region;
• Since the water heater constantly receives solar energy, with little water consumption, stagnation can form, where the coolant may well heat up to 300 degrees. Therefore, it is forbidden to use pipes made of plastic and galvanized iron. It is best to make a coil made of copper or stainless steel;
• It is imperative to make the insulation of the heating elements of the water heater, so as not to accidentally burn yourself;
• When choosing fasteners and insulation, one should also take into account the possibility of stagnation of the coolant and its strong heating. That is, it is better to choose materials with a safety margin. Many reputable manufacturers write the stagnation temperature in the specifications or on the device case. Focus on this value;
• Solar water heater panels should be located in an open area with maximum sun exposure. There should be no tall objects around that cast a shadow;
• To increase the efficiency of the water heater, it is necessary to fasten it on a special rack, if such an installation scheme is offered by the manufacturer;
• During installation, each type of heater can have its own characteristics. Here you need to focus on the manufacturer's recommendations.

Installation

Since the equipment is powered by solar energy, the installation of the heater will be carried out outdoors. Installation is recommended to be carried out on the roofs of buildings, on balconies or other architectural ledges.

The heater screen must face south. The installation is carried out at a certain angle to the horizon, which is equivalent to the geographical latitude of the area.

The water heater constantly absorbs energy and, for obvious reasons, the energy source cannot be turned off, therefore, in the case of low water consumption, the stagnation temperature can reach up to 300 ° C.

For this reason, zinc-coated plastic and steel pipes are not permitted. Pipelines made of copper or stainless steel will be optimal in operation.

The hot loop of the solar water heater must be insulated to avoid burns and fires. Consideration should be given to the operating temperature of the equipment when choosing thermal insulation and fasteners.

Manufacturers of solar water heaters indicate the exact stagnation temperature on the body of their products. The collector panels should be in an open area to allow easy access to sunlight. It is necessary to exclude the presence of possible obstacles.

Those. The key to the correct and efficient operation of the equipment is just a few rules:

• direction to the south;
• correct angle of inclination;
• unimpeded access to sunlight;

Incorrect installation will reduce the quality of the water heater, and the investment will not be justified. The type of heater can also play a role in how it is installed. When installing, take into account the type of equipment used.

There are such systems:

Passive

Includes self-sustaining absorption and storage of energy. Solar energy enters the heating object without control of this process, i.e. there are no mechanisms and control elements. It is a simple system that does not require much investment. However, the disadvantages are that the water heater works unevenly and not at full capacity.

The most obvious example is the darkened tank, which is located above the summer shower. In this passive mode, single-circuit systems operate in which the natural circulation process is used. For the full operation of the system, the receiving tank is placed above the collector, but this installation method is not always convenient. You can solve the issue using another way of the system.

Active

Free from the disadvantages of a passive system. Its functioning is based on the fact that the sun's rays, thanks to special devices, are converted into heat energy, which is systematically transferred to the heating tank and the consumer. The operation of such a heater is achieved due to forced circulation, which can be maintained in single and double-circuit systems. They also use and additionally install motors that turn panels and pumps, measuring equipment, as well as devices for monitoring and controlling the operation of the system.

Main manufacturers

Solar water heaters have found wide practical application in many European countries, China, Turkey, USA, Israel, Saudi Arabia. The production of these products in the world is growing steadily and, along with the demand, the number of companies in this segment is increasing.

Let's take a look at some of the big solar water heater companies. So, the top manufacturers in the world market:

• The Italian company produces KAIROS VT vacuum collectors. Available in 15 or 20 tube versions;
• The German manufacturer offers three models SKR21, SKR12, SKR6;
• Another German company that produces models with 6 or 12 pipes. Moreover, they can be combined into blocks to increase the power of the system;
• Sunrain Solar Energy. It is a Chinese manufacturer that produces solar water heaters;
• And another German company that offers two water heaters under the Vitosol 200 and 300 brands. These models differ in the design of the heating unit;
• Italian manufacturer producing the Ecotube model.

Water heater KAIROS VT

It is worth saying here that the products of these companies belong to the highest class and are provided with a guarantee, but not everyone can afford it. Therefore, most of the market demand is covered by little-known manufacturers.

Choosing a specific product

Today there are 4 types of such devices:

• Flat - used in areas with a large influx of solar radiation. If you live in the south of Russia or in the Crimea, this is what you need.

• Plastic - designed for use in the warm season and have a low efficiency. Suitable for residents of central Russia living in country houses in summer. Buying this type of solar water heater is a great way to save on energy costs and express your respect for nature. Well, a nice bonus is an affordable price.

• Vacuum is the most modern and efficient type of solar water heater. Distributed in countries with a pronounced seasonality and provide electricity production throughout the year. Vacuum solar water heaters, reviews of which are the most flattering, are suitable for everyone who lives outside the city all year round.

• DIY. Homemade solar water heaters are built by people who are passionate about technology. With a good knowledge of physics, an authentic little thing turns out, although in most cases it does not have enough power to heat a large volume of water. However, this is not at all scary, because the main purpose of self-construction of a water heater is to get pleasure.

Prices and what do they depend on?

With regard to specific figures, water heaters produced in Russia will cost about USD 700 - 800. This is a vacuum type model. Roughly the same prices for similar Chinese products. Water heaters from German manufacturers cost about 800-900 euros. It is more expensive, but they have the necessary fasteners in the kit, and copper and stainless steel are used for the manufacture of collectors. So that money will not be spent in vain.

Water heater Viessmann Vitosol 200
The following factors influence the price of a solar water heater:

• Brand;
• Body and heat sink material;
• build quality;
• the method of laying the insulation material and the cost of the material itself;
• glass thickness.

Naturally, the design differences, which were described above, are reflected in the price.

Using solar energy with the help of modern technologies, you can easily provide your private house or garden house with hot water.
And you need to make an initial investment, and then the installation will work for free. If you want to save money, then make a solar water heater yourself. But factory systems are, of course, more reliable and functional. If the article turned out to be useful to you, spread the link to it on social networks. This will help the development of the site. Vote in the poll below and rate the material! Leave corrections and additions to the article in the comments.

Main design features

The main question of those who took up the manufacture of a solar water heater concerns the size of the heat exchanger. There are no clear recommendations on this score. If you use, for example, steel radiators, then you should not take more than two panels. This will avoid weighting the structure. As for other materials, it has to be determined based on specific circumstances.

For the manufacture of the case, you can use plywood or wooden boards. The front side can be covered with transparent polycarbonate, which is quite durable. The storage tank is made of sheet materials. The best option is to purchase a ready-made container. All the elements can be connected using polymer or metal-plastic pipes.