Solar collectors for home heating as an alternative energy source

SHARE ON SOCIAL NETWORKS

FacebookTwitterOkGoogle+PinterestVk

The surface of the earth receives a large amount of solar radiation every day, which is mostly not used. However, it is a free source of heat that can be converted into usable energy for human use. Solar collectors for heating a house ideally cope with this task. You can learn about the principle of their operation, what are the differences between them and how effective they are from this article.

Solar collectors are a profitable source of energy for heating a home

What is a solar collector and its operating principle?

A solar thermal collector is a technical device that is capable of converting solar energy into heat. It is used to produce hot water, which can later be used for various needs. The main difference between solar collectors and other versions of similar equipment is the principle of changing the density of water during heating. Cold masses displace the heated water flow upward, so there is no need to use additional pumping equipment.

Diagram of the operating principle of a solar thermal collector

The operating principle of the device is as follows. Solar energy is absorbed in a receiving device, which can be copper or glass surfaces of dark or black color. Such materials are characterized by good energy absorption capacity.

Solar water heaters are conveniently located on the roof, where there is plenty of space and maximum sunlight. Here, such devices do not take up useful space and do not disturb anyone. Next, the heat from the storage tank is transferred to the coolant tank. This could be water, antifreeze or another liquid that is used in the heating system.

In most cases, a mixture of 40% glycol and 60% distilled water is used. The coolant, which is heated to a certain temperature, is supplied to the radiators through a piping system.

The direction of water movement in the system can change thanks to the mixer. Cooled and warm water constantly replace each other. This natural circulation occurs due to the expansion of warm water, which rises, displacing cold water into the heating tank.

A solar collector is a device for converting solar energy into thermal energy

This heating system must be equipped with a thermal insulation layer at least 25-30 cm thick, which will ensure its efficient and stable operation. It is better to use a rectangular tank as a storage tank for coolant. A backup heating element can be located here. It will automatically come into operation when weather conditions are created that are not conducive to heating the coolant to the required temperature.

Doubts away

In Mediterranean countries, where the number of sunny days is more than 300 per year, a solar collector for heating and water heating can be found on almost every roof. There is no doubt about the effectiveness of using this heat source in the southern regions of Russia. The climate of the middle zone is considered unfavorable for such energy installations. However, research and experiments prove the feasibility of using solar systems. Special work was carried out at the Institute of High Temperatures of the Russian Academy of Sciences. The average solar flux intensity, depending on the climate zone, is 150-300 W/sq. m. Peak figures reach 1000 W/sq. m.

The initial data for calculating the efficiency of the solar system was a surface ratio of 2 square meters. m of collector to the 100-liter volume of the storage tank. The probability of daily heating of water in the system is assessed by the following indicators:

• up to a temperature of +37 °C - 50-90%;
• up to a temperature of +45 °C - 30-70%;
• up to a temperature of +55 °C - 20-60%.

These dry figures indicate that in the cold season, the solar collector, even with the least number of sunny days, allows you to save up to 60% of energy for heating the house.

Advantages and disadvantages of solar collectors for heating water

In summer, solar collectors are able to fully provide the house with hot water. In the off-season, such an alternative heating system can reduce the load on the gas boiler, which will reduce gas consumption, while reducing financial costs.

Important! In winter, solar collectors work inefficiently, which is due to the small amount of solar radiation.

The collector acts as an additional source of free heat, thereby reducing dependence on gas. In the summer, there will be no financial costs required to obtain hot water.

A solar collector can provide a house with warm water in summer

Installation of a solar collector does not require obtaining a permit. When choosing equipment, you should study in detail all available information and consult with a knowledgeable seller. The installation of the system must be entrusted to a specialist or done independently if you have certain skills and abilities in the field of plumbing. The average lifespan of the system is about 15 years. During this time, you can use free solar heat for your own needs.

The disadvantages of such a system include the large financial costs that will need to be incurred when purchasing solar collectors. The average cost of one element is $500-1000. A system consisting of two collectors and assembled on a turnkey basis will cost between $2300-3000.

The intensity of solar energy differs at different times of the year, so solar collectors cannot be used as the only source of heat. For the system to operate, you will need a storage tank, the purchase of which will increase the cost of installing a solar water heating system.

Use of solar collectors in Europe and Russia

Residents of Europe have long come to the conclusion that using solar systems is profitable, comfortable and environmentally friendly. The absolute leader in European progress is Germany, followed by Greece; in Austria, 15% of private houses are equipped with DHW collectors. In Europe, solar collectors work everywhere - in private homes, schools, kindergartens, hospitals, and on farms. In Portugal, Israel and Spain, the installation of solar collectors that heat water is mandatory when building new houses.

The areas occupied by solar systems in Europe, America, Japan, and China are millions of square km, while in Russia this figure is 30,000 km2. There are several reasons - poor awareness of people and low levels of income.

Today, along with German, Austrian and Swiss manufacturers, Russian machine-building plants, as well as Belarusian and Ukrainian manufacturers, are entering the market of CIS countries, selling solar power plants at prices lower than their foreign counterparts.

Solar collectors for home heating: types of installations

By design, solar collectors can be flat or vacuum. The latter option is a more common type, which is characterized by ease of installation, high efficiency, and the ability to provide the required amount of heat to the entire house. A vacuum solar collector for heating a house, the price of which exceeds the cost of a flat product, is represented by a complex design that can be used to fully heat a room and heat water in any season of the year.

According to the type of design, solar collectors are vacuum and flat

There is a special type of installation called a collector-concentrator. It is a system of parabolic reflectors, which are located on one curved surface, where sunlight is concentrated at certain points. To obtain the maximum effect, it is necessary to change the position of the device, which can be in two planes, following the movement of the sun.

Depending on the coolant, liquid and air designs are distinguished. In the first case, distilled water or antifreeze is used, and in the second, heated air is used.

According to the type of coolant used, a distinction is made between passive and active systems. In the first option, the solar collector is used in conjunction with a storage tank. This system is suitable for hot water supply and is not equipped with additional engineering elements. The active option involves the installation of a solar collector and other technical devices, such as a pump, storage tank, safety valves, and additional coolant heating devices. Such a system can be used for both hot water supply and home heating.

According to the type of use, collectors can be passive or active

The method of heat transfer can be indirect or direct. The first option assumes the presence of a storage tank in which the thermal energy received by the external circuit from solar radiation is transferred to the internal circuit circulating in the heating and hot water systems. In direct-flow systems that are used for hot water supply, water circulation in the collector circuit occurs under the influence of temperature differences and due to the presence of additional elements in the form of valves and taps.

Classification of solar collectors for heating according to the heating temperature of the coolant

Air or water solar collectors for heating a house can be classified according to the degree of heating of its working parts and coolant. Depending on this criterion, low-, medium- and high-temperature installations are distinguished. Low-temperature options can provide heating of the coolant up to 50 °C. Such thermal collectors are used to heat water in showers in the summer, in irrigation tanks, to create comfortable conditions on cool spring and autumn evenings.

Medium temperature systems provide heating of the coolant up to 80 °C. Such installations are used for heating rooms and swimming pools. It is most advisable to install solar collectors of this category when arranging a private home. High-temperature systems are capable of heating the coolant to a temperature of 250-300 °C. Such devices are recommended for use on an industrial scale. They are used for heating commercial buildings, production workshops and other technological premises.

High temperature systems involve a complex process of conversion and transfer of thermal energy. The structures have impressive dimensions, requiring a lot of free space for their installation. The process of manufacturing the system is very labor-intensive and costly, which is associated with the use of specialized equipment. You won't be able to do this on your own.

Based on heating temperature, collectors are classified into low-, medium- and high-temperature

Is it profitable?

Everyone determines whether it is profitable to use solar collectors individually, depending on the region of residence, the need for thermal energy and depending on financial capabilities. The region of residence is an important criterion when determining the effectiveness of the use of devices used to convert solar energy into other types of energy. Solar activity (duration of sunshine) varies in different regions of our country, as can be seen in the diagram below.

From this diagram it is clear that the most favorable regions for the use of solar energy, with a duration of solar activity of more than 2000.0 hours per year, are located in the southern regions of the country. In these areas there are also no cold and long winters, which determines the possibility of successful use of solar collectors in heating and hot water supply systems in these regions of Russia.

If it is necessary to create a completely autonomous system from external, traditional suppliers of thermal energy, you should remember that by installing only a collector, it will not be possible to create such a system, since electrical energy is required to create coolant circulation and operate the automation system. Therefore, for complete autonomy, it is necessary to work out the issue of independent power supply to the connected facility. Consequently, in order to make a completely independent system, additional financial costs will be required, which will increase the payback period of the equipment.

Design features of a flat solar collector

The most popular option, according to numerous reviews, is a flat-type solar collector, which you can make yourself. This system is effective for organizing hot water supply during the warm season. In winter, the efficiency of the device is very low.

The collector body has a flat square or rectangular shape. It is made of metal or other material with a high thermal conductivity coefficient. The product is coated with dark paint to improve absorbent properties. Inside the body there is a plate in which there is a coil made of a small-section copper tube. The coolant circulates through the tubes. To minimize heat loss, thermal insulation material is laid inside the housing.

To prevent debris from penetrating into the device body, it is closed on top with a glass or polycarbonate lid, which can increase heating. For the collector to operate efficiently, it must be periodically wiped to remove dirt and dust.

It is recommended to install a flat solar collector in the southern regions, where this option is characterized by the best price and efficiency indicators. Such a device is distinguished by its self-cleaning ability, high efficiency in summer and low cost.

Flat-plate solar collectors are the most popular

However, flat collectors are characterized by significant heat losses, which arise due to the design features of the device. Such a system has low efficiency in the spring-autumn period. The structure is characterized by high windage, which causes the risk of damage to its elements during operation.

Operating principle and device features

The main element of the solar collector is the adsorber. It consists of a copper plate with a pipe attached to it. When absorbing the energy of direct sunlight acting on the solar system, the adsorbing element instantly heats up, transferring heat to the coolant circulating through the pipeline.

The type of surface of the collector determines its ability to reflect or absorb solar rays. For example, a device with a mirror surface perfectly reflects light and heat, while a black plate completely absorbs it. Consequently, for maximum efficiency, the copper plate of the adsorber is most often coated with black paint.

To also increase the amount of thermal energy emitted from the sun, it is necessary to wisely choose the glass covering the adsorber. For solar collectors, special glass with anti-reflective coating and a minimum percentage of iron contained in it is used. Such glass differs from ordinary glass not only in the reduced proportion of reflected light, but also increases transparency.

In addition, to prevent contamination of the glass, which also reduces the efficiency of the solar installation, the collector body is completely sealed or filled with inert gas.

At the same time, the adsorber plate releases part of the received thermal energy into the environment, heating the air interacting with the solar system. To reduce heat loss, the adsorbent element should be insulated. The search for the most effective methods of thermal insulation has led to the emergence of many types of solar collectors. Some of the common types are flat and tubular, or vacuum.

Characteristics of a vacuum solar collector for heating a house in winter

A vacuum solar collector is a rather complex device. The main working element is an expensive light-absorbing bulb with a transparent surface in which the tube is located. The work is based on the principle of a thermos. The vacuum flask allows sunlight to pass into the inner tube, where there is no air, which allows up to 95% of heat to be retained.

Helpful advice! It is impractical to make a vacuum solar collector with your own hands, which is due to the specifics of the production technology.

The lower part of the internal vacuum tube for the solar collector is occupied by antifreeze, which turns into a gaseous state when heated. In its upper part, heat is transferred to the collector with the coolant. At the same time, the antifreeze cools and condenses, returning to its original state.

A vacuum solar collector is a complex device, so it is quite expensive

The vacuum solar collector is characterized by a high efficiency value in poor lighting conditions and temperatures below -37 °C. It was specially designed for northern latitudes and can function in the absence of direct solar radiation. To operate effectively, the structure requires constant maintenance, which consists of cleaning its surface from contamination.

Important! The collector must be mounted at a certain angle, as indicated in the installation instructions for the device.

The main disadvantage is the high cost of the structure. If at least one tube fails, repair will be problematic, since all products are mounted in series.

Vacuum tubes

The design of a classic evacuated tube is quite simple. It is a double-walled glass flask with a vacuum created between the walls. There is a copper core (thermal channel) inside. Such a tube is called “coaxial”. Another type is the so-called “feather tubes”, single-walled flasks with a vacuum in the heat channel itself.

The operating principle of a vacuum tube depends on the structural features of its thermal channel and on the type of flask itself. Channels, like flasks, come in two types, direct-flow and heat pipe type.

The action of direct-flow channels is based on the direct flow of coolant through a U-shaped copper tube. The cooled liquid enters the tube from the heat collector, passes through it, heats up and returns to the heat collector. There it transfers the accumulated heat to the main coolant and returns to the tube.

The heat pipe works a little differently. The principle of its operation is based on heat transfer through an easily evaporating liquid enclosed in a thermal channel. The channel (tube) itself is made of heat-intensive metal (aluminum, copper). Sunlight heats the liquid, it evaporates from the lower end of the tube and condenses in a heat collector. The condensation flows down, where it is reheated by sunlight. The main coolant takes heat from the heat collector and transfers it through the collector further into the system.

Solar air collector for heating: product features

Air solar collectors use air as a heating medium for heating. The device can be made in two versions: in the form of a flat corrugated or perforated panel or a system of metal pipes.

The operating principle of a solar air collector for heating a house

The simplest option is a flat absorber, consisting of a panel and a tube with an inlet and outlet pipe. All elements are located in a box, the back and side walls of which are covered with thermal insulation. The panel is made of copper or aluminum and painted black. It is covered with a transparent protective surface made of glass, plastic or polycarbonate.

The air entering the panel is heated by contact with the metal. The ribs on the surface of the product increase heat transfer. For maximum efficiency, the structure should be installed on the south side of the house, with high-quality insulation. The system can be organized with natural or forced coolant circulation. The last option involves installing a fan.

Related article:

Waste oil boiler: a reliable and budget option for heating a room

Operating principle and distinctive features. Types of device. How to make it yourself. Manufacturers and popular models.

A system with natural circulation is used extremely rarely, which is associated with the slow movement of air masses, resulting in significant heat losses. Solar Fox air solar collectors can operate at temperatures as low as 25 °C, while for a water solar system the optimal value is 45 °C. Such structures can only be used for air heating of the house. Collectors are not able to heat water. The devices are characterized by low efficiency, have very impressive dimensions, but have a simple design, are easy to install and are affordable.

Helpful advice! To increase the efficiency of solar air systems, collectors can be built into south-facing walls during the construction of a house.

Solar air collectors can be flat or in the form of a system of pipes

The thermal conductivity of air is significantly lower than these indicators of water, which affects the efficient operation of the system. To avoid heat loss, all butt joints must be carefully insulated. Despite the existing shortcomings, the air solar collector copes well with the task of heating indoor air with a temperature difference between inside and outside of 15-17 ° C.

Application specifics

Unlike heat generators and heat pumps, which convert energy from groundwater and air masses warmed by the sun, solar collectors operate from direct sunlight acting on their surface. The only nuance of solar collectors is that at night they are in passive mode.

The daily performance of a solar installation is influenced by factors such as:

• Length of daylight , which in turn depends on the geographic latitude of the region and the time of year. So, for example, in the central part of Russia, the solar collector will function at its maximum in summer, and at its minimum in winter. This is due not only to the length of the day, but also to the change in the angle of incidence of sunlight on the solar panels;
• Climatic features of the region. As a rule, on the territory of our country there are many areas over which for more than 200 days a year the sun is hidden behind layers of clouds or behind a veil of fog. Despite the fact that the solar collector can capture even scattered sunlight, in cloudy weather its productivity is significantly reduced.

Requirements for materials for the manufacture of a homemade solar collector

To make the frame of a solar collector for heating with your own hands, plywood, wooden beams, OSB boards or other similar options are used. As an alternative, you can use an aluminum or steel profile with inserts made of similar materials, which will give the structure strength and reliability. However, such a case will have a high cost.

Materials must meet the requirements for structures located outdoors. Since the average service life of a solar collector is 20-30 years, it is necessary that the materials have high performance characteristics that will remain unchanged throughout the entire service life of the installation.

Wood for the body must be treated with water-polymer compositions and coated with paint and varnish emulsions. The steel profile must be reliably protected from corrosion.

Plywood, OSB boards or timber are used to make the collector frame

To make a heliostat absorber with your own hands, you use available materials. The coil can be made from rigid PVC pipe with fittings, flexible HDPE pipe, bent copper or metal tube. The heat exchanger of an old refrigerator is suitable for the absorber. The element can also be made from aluminum cans or plastic bottles. The main selection criterion is the thermal conductivity of the material.

To prevent heat loss, the housing should be insulated on all sides. For these purposes, mineral wool or polystyrene foam is mainly used. The foil version of the insulation has proven itself well, which will provide not only thermal insulation, but also reflection of the sun's rays from the surface.

Important! It is necessary to make grooves in the foam insulation layer for laying the coil.

The heat exchanger is covered with a protective surface, which can be tempered glass or monolithic polycarbonate. The material should have a grooved rather than smooth surface.

To prevent heat loss, the collector body is insulated with mineral wool or polystyrene foam

Pros of a solar water heating system

Solar heaters have the following advantages:

1. Relatively simple design.
2. The reliability level is quite high.
3. Such a system can be used for a year.
4. The period of use is more than a dozen years.
5. The commissioning of such a system helps to reduce the cost of electrical energy and coolants.
6. Installation of the unit is carried out without prior obtaining a permit. Installation takes minimal time and is simple.
7. The weight of the structure is relatively light.
8. Autonomous operating mode.

Flaws

Before using solar water heaters for your home, consider the disadvantages:

1. Factory-designed equipment is more expensive.
2. The level of efficiency depends on various indicators: climatic region, time of year, etc.
3. Hail and wet snow have a detrimental effect on the condition of the installation and its performance.
4. Installation of the container in which heat is accumulated takes some time. This process requires additional costs.

Despite all its disadvantages, solar water heating is growing in popularity. After all, it is considered environmentally friendly.

Making a flat-plate solar collector with your own hands

At the first stage, the solar collector for heating is calculated based on the area of ​​the room. Its dimensions are also determined by the level of sun activity in a given region, the location of the house, and the characteristics of the area.

The collector body is made of wood or glass. You can use old glazed windows. To create an absorber, aluminum or copper tubes, a rolled rubber hose, and steel flat batteries are suitable. You can create a manifold from black polypropylene pipes.

Thermal insulation material in the form of polystyrene foam or mineral wool is placed on the bottom of the housing. Next, the entire area is covered with a metal sheet made of thin steel or aluminum to enhance the heat transfer effect.

The coil pipes are mounted on top, which are attached to the metal sheet using brackets. Its ends are brought out. The surface of the structure is covered with impact-resistant tempered glass or transparent polycarbonate, leaving a gap of 10-15 cm for good heat transfer. The storage tank is protected with heat-insulating material or painted black. A heating element is connected to it, from which the pipes for the heating system of the house are routed.

A flat-type solar collector can be made by hand

Important! All butt joints must be securely sealed.

Making a Solar Water Heater with Copper Absorber

The solar collector proposed for production heats water to a temperature above 90 °C on a sunny winter day, and to 40 °C in cloudy weather. This is enough to provide the house with hot water. If you want to heat your home with solar energy, you will need several such installations.

Required materials and tools

To make a water heater you will need:

• sheet copper with a thickness of at least 0.2 mm, dimensions 0.98×2 m;
• copper tube Ø10 mm, length 20 m;
• copper tube Ø22 mm, length 2.5 m;
• thread 3/4˝ - 2 pcs;
• plug 3/4˝ - 2 pcs;
• soft solder SANHA or POS-40 - 0.5 kg;
• flux;
• chemicals for blackening the absorber;
• OSB board 10 mm thick;
• furniture corners - 32 pcs;
• basalt wool 50 mm thick;
• sheet heat-reflecting insulation 20 mm thick;
• lath 20x30 - 10m;
• door or window seal - 6 m;
• window glass 4 mm thick or double glazing 0.98x2.01 m;
• self-tapping screws;
• dye.

In addition, prepare the following tools:

• electric drill;
• set of metal drills;
• “crown” or cutter for woodworking Ø20 mm;
• pipe cutter;
• gas-burner;
• respirator;
• paint brush;
• a set of screwdrivers or a screwdriver;
• electric jigsaw.

To test the circuit you will also need a compressor and a pressure gauge designed for pressure up to 10 atmospheres.

A simple gas torch is suitable for soft soldering.

Instructions for the progress of work

1. Using a pipe cutter, the copper tube is cut into pieces. You will get 2 parts Ø22 mm 1.25 m long and 10 elements Ø10 mm 2 m long.
2. In thick pipes, make an indentation from the edge of 150 mm and perform 10 drillings Ø10 mm every 100 mm.
3. Thin tubes are inserted into the resulting holes so that they protrude inward by no more than 1–2 mm. Otherwise, excessive hydraulic resistance will appear in the radiator.
4. Using a gas burner, a hot air gun and solder, all parts of the radiator are connected to each other.
5. Plugs and threads are soldered in pairs along the diagonals of the radiator to the 3/4˝ pipes.
6. Having closed the outlet thread with a plug, screw a fitting onto the inlet of the assembled manifold and attach the compressor.
7. Place the radiator in a container with water and use a compressor to pump up a pressure of 7–8 atm. The bubbles rising at the joints indicate the tightness of the solder joints.
8. After checking the tightness, the radiator is dried and degreased. Then they start soldering the copper sheet. The absorber sheet should be soldered to the tubes using a continuous seam along the entire length of each element of the copper circuit.
9. Since the solar collector absorber is made of copper, chemical blackening can be used instead of painting. This will allow you to get a real selective coating on the surface, similar to what is produced in the factory. To do this, pour a heated chemical solution into a container to check the tightness and place the absorber face down. During the reaction, the temperature of the reagents is maintained in any available way (for example, by constantly pumping the solution through a container with a boiler).
10. Parts are cut out of the OSB sheet to assemble the solar collector body - bottom 1x2 m, sides 0.16x2 m, top 0.18x1 m and bottom 0.17x1 m panels, as well as 2 support partitions 0.13x0.98 m.
11. A 20x30 mm rail is cut into pieces: 1.94 m - 4 pcs. and 0.98 m - 2 pcs.
12. Holes Ø20 mm are made in the side walls for the inlet and outlet pipes, and 3–4 drillings Ø8 mm are made in the lower part of the collector for microventilation.
13. Cutouts are made in the partitions for the absorber tubes.
14. A support frame is assembled from 20x30 mm slats.
15. Using furniture corners and self-tapping screws, the frame is covered with OSB panels. In this case, the side walls should rest on the bottom - this will prevent the body from sagging. The bottom panel is lowered 10 mm from the rest to cover it with glass. This will prevent precipitation from getting inside the frame.
16. Install internal partitions.
17. The bottom and sides of the body are insulated with mineral wool and covered with rolled heat-reflecting material.
18. The absorber is placed on the prepared space. To do this, one of the side panels is dismantled, which is then put in place.
19. At a distance of 1 cm from the upper edge of the box, the inner perimeter of the structure is sheathed with a 20x30 mm wooden strip so that its wide side touches the walls.
20. A sealing gum is glued around the perimeter.
21. Glass or a double-glazed window is laid, the contour of which is also covered with a window seal.
22. Press the structure with an aluminum corner, in which holes for self-tapping screws are pre-drilled. At this stage, the collector assembly is considered complete.

To prevent moisture ingress and heat leakage, at all stages the joints and places where the parts are mated are treated with silicone sealant. To protect the structure from precipitation, the wood is coated with a special compound and painted with enamel.

Options for creating an air solar collector with your own hands

Making a traditional air solar collector for heating your home with your own hands begins with creating a frame from wooden boards. The back and end walls should be insulated with mineral wool. The housing is fixed to the wall. All gaps must be insulated with foam. On the sides there are holes for pipes for the entry and exit of air masses. External elements are securely wrapped with heat-insulating material.

A perforated metal sheet made of aluminum, which is characterized by high thermal conductivity and low cost, is used as an absorber. To increase selective qualities, it is coated with black paint. A sheet of glass or polycarbonate is placed on top.

Important! The degree of heating is determined by the dimensions of the solar panel.

Water pipes can be used as an absorber for the air collector

The absorber can be made of rectangular water pipes, which are installed on an aluminum sheet and fixed to it using mounting tape and self-tapping screws. The back wall of the wooden case is insulated with mineral wool, and the side walls with expanded polystyrene. The pipes are painted black and covered with a sheet of tempered glass or polycarbonate.

An even simpler design is made from corrugated sheets. The frame is made of wooden blocks. An exit hole is made in the bottom. Corrugated sheeting with many holes throughout the entire area of ​​the product is laid on the beam, which will ensure air flow.

A good solution is to build an air collector on the window. This is a fairly effective option that allows you to heat the room well. The frame is made of aluminum frames and attached to the window in the form of a mosquito net. The rear wall is made of aluminum sheet, in which holes are made in the lower (for intake of cold air) and in the upper (for removal of warm air) parts. The role of an absorber can also be performed by black foil, which is covered with a protective PVC film.

Flat solar converter

The flat-plate solar collector is a self-contained panel consisting of three components:

• Solar radiation absorber. It is painted with black paint or a special coating is applied.
• Top transparent coating. Made from tempered glass or polycarbonate.
• A system of tubes through which the coolant circulating in it is heated. Typically made from copper.

The back side of the panel has an effective thermal insulation coating. One or more of these panels are connected to the supply line of the storage tank. This type of system has a relatively low cost and good performance in warm seasons. The downside is low efficiency at subzero temperatures and significant heat loss.

Solar collector for home heating: reviews and recommendations for choosing a device

When choosing a solar collector, you should take into account some nuances. Flat models are more durable than other varieties. However, such structures are not suitable for repair. A minor breakdown can damage the entire absorption system, which leads to the cost of purchasing a new one. You can save money by making a flat solar water heater with your own hands, which heats the coolant 30-40 °C above the ambient temperature.

When choosing a collector, you need to take into account that flat models are more durable, but cannot be repaired

Vacuum solar heating systems are very sensitive to external influences and are more susceptible to damage, which is due to the fragility of hollow pipes. However, if one of the flasks fails, it can be replaced with a new one. This collector is much more efficient in winter than the flat version, since it provides heating over a wider range and is able to maintain the temperature for a long time.

The performance of a vacuum manifold depends on the size of the tubes. The shorter they are, the less thermal energy generation. The best option is a system with several flasks 2 m long and 6 cm wide. To ensure effective thermogenesis, a straight or U-shaped insert should be located in the inside of the flask.

Air options have a simple design, rarely require repairs, and can withstand very low temperatures. Their service life exceeds the service life of other systems. However, they do not heat the room very well.

Helpful advice! Before purchasing a system, it is necessary to perform a calculation of the solar collector with the participation of a qualified specialist in this field of activity.

Vacuum collectors provide heating over a wider range than flat-plate collectors

It is important to choose the right location to install the system. A DIY solar water heater must be placed on the south side or with a deviation of 30° from it. Measures must be taken to remove precipitation during the winter period. The device can be positioned vertically, which will eliminate the problems associated with clearing snow from the collector. However, this situation will negatively affect the efficiency of the heater.

Price and payback

From a financial point of view, solar solar collectors must be considered an investment. The payback period can vary from several months to several years. It depends on when and how many times the system will be used. The service life of solar solar collectors can be more than 30 years. But they will pay for themselves in any case, given that they require virtually no maintenance.

The performance of the entire system depends entirely on the quality of each element and correct installation. Solar solar collectors will not be able to work at full capacity if the rest of the equipment is incorrectly selected. Installation and design are best left to professionals.

Sequence of installation of a solar heating system for solar heating

After purchasing or making your own solar collector for heating your home, you can begin installing it.

Installation begins with the installation of a storage tank with a capacity of 20-40 liters. You can also use several small tanks that are connected in a series chain using pipes. The tank should be insulated to avoid rapid loss of thermal energy. The storage tank is located at the highest point. It should be taken into account that when the system is filled with liquid, the structure will have significant weight, which will require reinforcement of the overlap at its location.

Next, you install a solar collector with your own hands for heating water, which is located on the south side of the building at an angle relative to the horizon of 35-45°. The system is then connected with pipes, which is necessary to obtain a closed hydraulic circuit. For this, inch or half-inch elements are used. Smaller diameter parts are used to organize the pressure part of the system. Pipes must be insulated, which will reduce the likelihood of heat loss.

In order for the collector to work efficiently, it is necessary to correctly assemble and install the structure

Important! The efficient operation of the heating collector depends on the tightness of all connections.

Upon completion of installation, the system is tested. It is filled through a pipe at the bottom of the collector, which will eliminate the possibility of air locks. The coolant enters the storage tank until the optimal level is reached, which is regulated using a float valve. The heated liquid will rise in the front chamber and enter the heating system. Natural circulation occurs until the temperature of the fluid entering the radiator and that leaving the manifold are equalized.

When arranging a hydraulic system, it is necessary to install shut-off valves that prevent the reverse circulation of the coolant into the storage tank from the manifold. This phenomenon occurs when the ambient temperature decreases, which is typical for the evening or night time.

How does a DHW system work from a solar system?

Solar water heating systems can compensate about 50% of the heat costs for heating water. Savings per year are about 300 m³ of gas or 4 m³ of firewood. Even despite the need for an initial investment, a storage water heater powered by solar panels is extremely profitable. For commercial use, payback occurs after 2-3 years of intensive use, and the service life of the collectors ranges from 30-50 years.

To understand how profitable hot water supply using solar collectors is, it is worth considering several important questions:

• how does the solar system work?
• how much water the solar collector can heat during the day.

A good understanding of the above points will help you choose the most suitable solar system in each specific case.

The principle of heating water by the sun

There are several types of collectors, differing in the principle of heat absorption or accumulation. All equipment is divided into two groups:

• Tubular vacuum collectors - heat accumulation is carried out thanks to special flasks. During the production process, air is pumped out of glass tubes, which leads to the creation of a vacuum, which plays the role of a kind of heat insulator. The inside of the flask is coated with a highly selective layer. There is also an aluminum or copper plate in contact with the heat exchanger tubes, which for a solar water heater are made of copper. The operating principle of tubular collectors is as follows:
  1. in the tubes, thanks to the highly selective coating and internal structure (reminiscent of a thermos flask), the air is heated to 280-300°C;

  heat is transferred through the plate to the circulating fluid;

• The coolant enters a separate or monoblock storage tank, and the water is heated.

According to their design, tubular vacuum collectors are divided into several groups: with U-shaped (coaxial) or direct-flow tubes.

• Panel collectors - heaters use the greenhouse effect. The sun's rays pass through the transparent surface and hit the absorber, which accumulates heat. The solar water heater is designed like this:
  1. regular or tempered glass, with various additional functions (anti-vandal, anti-hail, self-cleaning, etc.)

  housing made of adonized aluminum;

• absorber - the role of a heat exchanger is performed by a copper plate placed between two glasses. The selective surface consists of metal treated with a special heat-absorbing paint. A flow pipeline is soldered to the heat exchanger, through which a liquid is supplied inside the panel, removing excess heat. Absorber, the most important part of a solar water heater. The thermal efficiency of the panel collector depends on the quality of the absorbent coating.

The operating principle of solar hot water collectors of tubular and panel type is based on ordinary physical laws. Ultraviolet radiation passes through the earth's atmosphere without losing much heat. When the sun's rays hit a hard surface, they warm it up. In turn, heated objects give off heat to the environment. Heating occurs in a similar way in the solar system.

The sun's rays fall on the absorbent surface, which becomes very hot due to the fact that it is painted in a dark color. Heat is accumulated using an absorber and sent to a storage tank. The described operating principle remains the same for all solar collectors, regardless of the internal structure.

Types and methods of accumulating solar thermal energy affect the operating characteristics of solar water heating systems. Tubular water heaters are characterized by greater heat transfer and are capable of operating at temperatures down to –50°. Although vacuum flasks are more expensive, their thermal parameters: heating speed and intensity are better compared to panel collectors.

How much water can a solar collector heat?

It all depends on several factors: the method of heating and heat accumulation, time of year, weather. Separately, what kind of recirculation system is used is taken into account. The average value for a solar system per 1 m² is considered to be the following heating capabilities per hour:

• 100 liters at 7 °C;
• 50 liters at 14 °C;
• 25 liters at 28 °C;
• 15 liters at 46 °C;
• 10 liters at 70 °C.

If the solar collector is in cloudy weather, it can reduce the heating rate of the hot water supply; in clear sunny weather, on the contrary, it can increase it, so the list shows average values.

In warm summer weather, in the absence of clouds, the water heater heats up about a bucket of water in just an hour, which is enough for an economical shower. During daylight hours, about 200 liters are collected. hot water with a temperature of about 40°, provided that a collector with more than 1.5 m² of absorbent area is used.

In winter, the consumer will be faced with the fact that the heat received will not be enough to produce the required amount of hot water. The problem is solved by installing a storage tank.

The principle of operation of the collector at low ambient temperatures changes somewhat. If in summer it was possible to connect a boiler and periodically, once an hour, “dump” hot water into it, then in winter the water heater will function normally only in an indirect heating system. The essence of this connection is as follows:

• in winter, the water in solar collectors heats up to a temperature of 30°C, which is not enough for washing;
• a buffer tank with two heat exchangers is connected to the DHW system, for the boiler and solar collector;
• solar water heaters heat water to a temperature of 25-30°C;
• the main heating is carried out by a gas, electric or solid fuel boiler, bringing the temperature to 60-70°;
• When the hot water tap is opened, hot water is supplied to the user.

A solar water heater works in winter to compensate for the energy resources required for the operation of the hot water supply system. Autonomous hot water supply using solar collectors alone is impossible. It is required that the DHW system contains a water heater capable of meeting 100% of the water supply needs.

What do solar systems run?

The coolant for collectors is selected depending on the operating conditions. Thus, for all-season systems, a special antifreeze is used that does not freeze in the winter season. In summer, the water heating circuit is filled with distilled water.

In connection with the choice of coolant, there are several general recommendations:

• Operation in winter - the composition of anti-freeze liquids for solar water heaters is a mixture of propylene glycol with water and the addition of anti-corrosion substances. Proportions are selected depending on the average freezing temperature of the environment:
  1. –20°C, a 40% solution is needed: for 10 liters of coolant / 6 liters. propylene glycol;

  –30°C you will need a 50% solution, half distilled water and propylene glycol.

NaOH alkali must be added to the finished coolant. Propylene glycol turns into acid under prolonged exposure to temperature changes. After adding alkali, the acid balance pH should not exceed 7. In ready-made antifreezes, all components are added in optimal proportions.

• Seasonal operation - the collector will be used from spring to early autumn. Distilled water should be used as a coolant to prevent scale formation inside the pipes.

The advisability of using ready-made antifreeze liquids (which cost approximately 3 times more than a similar composition prepared at home) has been questioned. You should purchase factory-made antifreeze in cases where it is not possible to make them yourself.

Domestic manufacturers of solar collectors for home

A popular manufacturer of solar collectors is the New Pole company, which offers a wide range of models at affordable prices. A special place is occupied by flat devices made of aluminum. The coolant circulates through copper tubes equipped with double insulation protection, which ensures efficient operation of the system at low temperatures.

The domestic company Novy Polyus offers a wide range of collectors

Home heating equipment can be purchased complete with a storage tank, temperature controller and circulation pump. The average price of a solar collector will be 20-22 thousand rubles.

Another successful manufacturer of solar-to-thermal energy converters is the AltEnergia company, which produces flat-plate and vacuum collectors. The first version of the products can be supplied together with a boiler with a volume of 200-500 liters, which operates on the principle of indirect heating. Vacuum collectors are equipped with storage tanks of 100-1000 liters and circulation pumps.

Important! Products from AltEnergia are certified in Germany.

A flat device will cost about 13 thousand rubles. The price of a vacuum solar collector will be 35-50 thousand rubles.

A flat solar collector from AltEnergia will cost about 13 thousand rubles

The domestic manufacturer ANDI Group specializes in the manufacture of vacuum-type manifolds. The main feature of the product is their ability to adapt to difficult weather conditions. Collectors are capable of converting energy even on cloudy days. Each bulb has a three-layer coating, which ensures maximum absorption of solar radiation. You can buy a solar collector for an average of 25-35 thousand rubles.

The NPO Mashinostroyenia company produces a range of solar collectors that are distinguished by their simple modification, functionality and affordable cost. The latest technologies are used in the manufacture of products. A distinctive feature of the collectors is the presence of a multilayer absorber, which is applied to the absorber using magnetic sputtering. This layer promotes maximum capture and retention of solar energy, resulting in device efficiency of 85-90%. You can buy a solar system for 15-20 thousand rubles.

Payback period for a solar system

A simple calculation will help you understand how quickly expensive solar collectors pay for themselves. For example, it will be a flat device with an area of ​​2 “squares” with a daily output of 6.4 kWh of heat.

When the main source of thermal energy is an electric boiler, the kilowatt-hour it produces will cost 5 rubles (according to 2022 prices), which means that the daily savings on power supply when operating a flat device will be 6.4x5 = 32 rubles, and the payback period at the price of the device is 20 thousand – 625 days (20000:32=625).

When the main heat source is a gas unit, a kilowatt-hour of energy will cost 0.7 rubles, and the daily savings will be 6.4 x 0.7 = 4.48 rubles. The payback period will increase to 4464 days or 12 years. If we take into account that the average life of a collector is no more than 15 years, we can conclude that in this case the solar system will never pay off.

Model overview

"Summer resident"

This model costs about 18,500 rubles. This collector is capable of heating water up to 95 degrees and is perfect for country houses. Has a 12 month manufacturer's warranty. This time is enough to ensure its reliability.

This model has the following technical characteristics:

1. The 100 liter tank is made of high quality stainless steel.
2. The vacuum tube is 150 cm long.
3. Tube diameter (external) 4.8 cm.
4. The maximum possible pressure in the tube is 0.6 MP.
5. The design is resistant to hail up to 0.5 cm.
6. The tubes are made of borosilicate glass, which has an absorbing effect.
7. The total weight of the collector is 45 kg.

Equipment:

• set of anthers (sealing) – 1 pc.;
• vacuum tubes – 16 pieces;
• frame and set of bolts – 1 pc.;
• expansion tank – 1 pc.;
• thermos tank 100 l. - 1 PC.;

CP-II-20-175 from ANDI Group

The kit includes:

• water tank with a volume of 175 l., the internal circuit is made of stainless steel, and the external circuit is made of galvanized painted steel;
• vacuum tubes – 20 pcs.;
• TNC-2 (controller).;

The thermal insulation of the tank is made of polyurethane (50 mm). Internal diameter 36 cm, external 46 cm, steel frame 1.5 mm thick, galvanized. Net weight of the unit is 86 kg.

Which ones exist?

Depending on the temperature that the plates can reach, collectors are:

• low temperatures - they do not provide high-power energy, they heat water no more than 50 degrees Celsius;
• medium temperatures - they heat water up to 80 degrees, so they can be used for heating rooms;
• high temperatures - they are used mainly in industrial enterprises, and it is impossible to make them at home.

Integrated collectors are divided into:

• cumulative integrated;
• flat;
• liquid;
• air.

Cumulative integrated or otherwise thermosiphon collector. It can not only heat water, but also maintain the desired temperature for some time. It does not have pumps, so it is much more economical than other options. The storage device is a structure of one or more tanks filled with water and placed in a heat-insulating box. On top of the tanks there is a glass lid that passes through the glass and heats the water. This is an inexpensive, easy to maintain and easy to operate option. However, in winter its use is very difficult.

A flat-plate collector looks like an ordinary flat metal box, inside of which there is a black plate that absorbs sunlight. The glass lid of the box enhances it, the glass has a low iron content, thus helping to absorb all the rays. The box itself is thermally insulated, and the black plate is heat-receiving, which is why heat is released. However, the efficiency of the wafer is only 10%, so it is additionally coated with a layer of an amorphous semiconductor. Flat-plate collectors are used for heating water in swimming pools, heating premises and other domestic needs.

In liquid storage devices, the main coolant is liquid. They are glazed and unglazed, with a closed and open heat exchange system.

Air collectors are much cheaper than their water counterparts. They do not freeze in winter and do not leak. They are used for drying agricultural products.

There is another type - concentrators, they differ in the concentration of sunlight. This happens thanks to the mirror surface, which directs the light onto the absorbers. Their main drawback is the inability to work on cloudy days, so they are used in countries with hot climates.

Solar ovens and distillers. Distillers work on the principle of water evaporation, thereby not only providing heat energy, but also purifying the water. Stoves are also used for both heating and sterilizing water.