Solar collectors for home heating as an eco-source of energy

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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.

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.

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.

Other system components

It is not enough to simply collect the heat emitted by the sun. It still needs to be transported, stored, transferred to consumers, all these processes need to be controlled, etc. This means that in addition to the collectors located on the roof, the system contains many other components, perhaps less noticeable, but no less important. Let's focus your attention on just a few of them.

Coolant

The coolant function in the collector circuit can be performed by either water or non-freezing liquid.

Water has a number of disadvantages that impose certain restrictions on its use as a coolant in solar collectors:

Firstly, at negative temperatures it freezes. To prevent the frozen coolant from breaking the pipes of the circuit, it will have to be drained as cold weather approaches, which means that in winter you will not receive even small amounts of thermal energy from the collector.
Secondly, the boiling point of water that is not too high can cause frequent stagnation in the summer.

Non-freezing liquid, unlike water, has a significantly lower freezing point and an incomparably higher boiling point, which makes it more convenient to use as a coolant. However, at high temperatures, the anti-freeze may undergo irreversible changes, so it should be protected from excessive overheating.

Pump adapted for solar systems

To ensure forced circulation of the coolant along the collector circuit, a pump adapted for solar systems is required.

Heat exchanger for hot water supply

Heat is transferred from the solar collector circuit to the water used in the hot water supply or to the coolant of the heating system via a heat exchanger. As a rule, a large volume tank with a built-in heat exchanger is used to accumulate hot water. It is rational to use tanks with two or more heat exchangers: this will allow you to take heat not only from the solar collector, but also from other sources (gas or electric boiler, heat pump, etc.).

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

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.

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.

How to make it yourself

The simplest, but nevertheless effective option is a flat solar collector, which uses water as a coolant.

The body of the device is made from materials available at hand. It can be wood, profiled black or non-ferrous metal. The dimensions of the frame are determined by the location of the solar collector, its purpose and the availability of the required materials.

Insulation is placed in the internal space of the housing, on top of which a copper tube is laid. To create a larger absorbing area, the tube is laid in the shape of a coil. To increase the efficiency of the device, you can put a layer of foil under the tube (not shown in the diagram), this will reduce heat loss to the bottom side of the device and increase the temperature in the internal space of the case.

From the outside, the case is covered with protective glass, the cracks are sealed. Cold and hot water pipes are installed at the entry and exit points of the pipes. A device manufactured in this way can be used for hot water supply to a summer shower and heating water in a swimming pool; for this, the collector pipes are connected to the selected systems, after which the device is ready for operation.

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.

Design nuances and classification

Vacuum-type collectors are classified according to the type of glass tubes installed in the structure, or according to the characteristics of the thermal channels. The tubes are usually coaxial and feather type, and the heat channels are U-shaped direct-flow and heat pipe type. .

Characteristics of coaxial tubes

Coaxial tubes are a double glass thermos flask with an artificially created vacuum space between the walls. The inner surface of the tube has a layer of special heat-absorbing coating, so the actual heat transfer occurs directly from the walls of the glass bulb.

Coaxial tubes are made of high-strength borosilicate glass, which has high light transmittance. The elements, depending on the manufacturer, have up to three layers of magnetron sputtering, demonstrate excellent strength and resistance to various atmospheric conditions (rain, hail, etc.), withstand pressure of 1 MPa and reliably serve for 15 years

As an absorbing element, a copper tube containing an ether composition is soldered into a glass tube. During the heating process, it evaporates, effectively gives up its heat, condenses and flows to the bottom of the tube. The cycle is then repeated, thus creating a continuous heat exchange process.

Features of feather tubes

Vacuum feather tubes have greater wall thickness than coaxial ones, and consist not of two, but of one flask. The internal copper absorption element is equipped along its entire length with a durable amplifier - a corrugated plate with a high-level energy-absorbing coating.

Thanks to this design feature, the vacuum is located directly in the thermal channel, part of which, together with the absorbent, is integrated directly into the flask.

The feather vacuum tube contains a plate inside that is shaped like a feather. The level of efficiency exceeds the capabilities of its coaxial counterpart, but has a significantly higher cost and is difficult to replace if the integrity of the bulb is damaged or the heating element fails

Collectors made from feather vacuum tubes are considered the most efficient in their class, perform well and provide reliable service for many years.

Operating principle of the heat pipe

Heat pipes consist of closed tubes containing an easily evaporating liquid composition. Under the influence of sunlight, it warms up, moves to the upper region of the channel and is concentrated there in a special heat collector (manifold).

At this moment, the working fluid gives up all the accumulated heat and falls down again to resume the process.

The heat-pipe heat exchanger sleeve is connected to the manifold heat exchanger through a special socket soldered into the 1-pipe heat exchanger itself, or is wrapped around a 2-pipe heat exchanger.

The working element of the heat pipe is made of copper, and in more rare cases - of aluminum. It exhibits high resistance to operational loads, serves reliably for 15 years, has a reasonable cost and is one of the most popular elements of modern tube-type vacuum solar systems

The released energy is taken from the thermal reservoir by the coolant and transferred further through the system, thus ensuring the availability of hot water in taps and radiators. The heat pipe system is easy to install and demonstrates high operating efficiency.

Collectors equipped with vacuum heat pipes have a good level of reliability and are suitable for use not only in everyday life, but also in high-pressure solar thermal systems

In the event of a breakdown or failure without any difficulties, it is possible to replace the damaged unit with a new one without resorting to reconstruction of the entire system.

Repair work can be easily carried out directly at the location of the collector, without dismantling the unit and without applying unnecessary effort to the work.

Description of U-shaped once-through heat exchanger

The tube of the direct-flow heat exchanger is shaped like the letter U. Water or the working coolant of the heating system circulates inside. One part of the element is intended for cold coolant, and the second correctly removes the already heated one.

When heated, the active composition expands and enters the storage tank, thus creating natural circulation of liquid in the system. A special selective coating applied to the internal walls increases the heat absorption capacity and improves the efficiency of the system as a whole.

Compared to heat-pipe type tubes, U-shaped products have greater hydraulic resistance, place higher demands on the coolant and are significantly more expensive. Collectors operating on direct-flow U-tubes cannot operate under high pressure and provide high-quality heat transfer only during the warm season

U-type tubes demonstrate high performance and provide solid heat transfer, but they have one significant drawback. They form one integral structure with the manifold and are always mounted together with it.

It will not be possible to replace a separate single tube that has failed. For repairs, it will be necessary to dismantle the entire complex and put a new one in its place.

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.

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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.

Varieties

All devices can be divided into 2 categories: according to the heating principle and the method of storing the coolant. When choosing a solar system, you should always choose based on the usage parameters. Depending on the design, the method of operating and maintaining the equipment differs.

Manifolds with built-in tank

Monoblock installations are designed for operation in the spring-autumn period. They are turned off during the winter months. Models with a built-in tank are easy to install and use. All you need to do is connect it to the water supply system.

Principle of operation:

the sun's rays fall on the absorbing panel (absorberum);
the resulting energy is transferred to the coil, which is located in the tank;
thermal energy is transferred from the coolant to the water.

On a good sunny day, such a collector can heat up to 200 liters of water. Collectors with a built-in tank operate without pressure, so installation is carried out at the highest point - the roof of the house. This is done to ensure the necessary water pressure.

Such installations are in wide demand due to their ease of use and easy installation. Most often they are used for summer houses and summer cottages.

The main operating principle is water circulation. Warm water at the top, cold at the bottom. During installation, it is important to install the liquid container above the collector.

Solar systems with a remote tank

These types of collectors can operate all year round. The only condition is that the temperature should not fall below -50 degrees. An external indirect heating boiler is used to heat water, and antifreeze is used as a coolant.

Principle of operation:

the absorbing panel receives heat and transfers it to the coolant;
under pressure, the coolant enters the heat exchanger of the storage tank;
As the antifreeze passes through the coil, it heats the water.

Such solar systems work with a connection to a pumping group. Management is carried out automatically.

The advantage of a solar collector with a remote tank is the ability to generate energy all year round, under certain conditions. However, such installations require the connection of additional equipment, and the operation of the collector depends on electricity - its disconnection may affect the operation of the installation.

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

Collectors from scrap materials

Assembling a solar collector for heating a house with your own hands is both cheaper and more interesting, because it can be made from various available materials.

From metal pipes

This assembly option is similar to the Stanilov manifold. When assembling a solar collector from copper pipes with your own hands, a radiator is welded from the pipes and placed in a wooden box lined with thermal insulation from the inside.

Copper pipes will be the most effective; aluminum pipes can also be used, but they are difficult to weld, but steel pipes are the most successful option.

Such a homemade collector should not be too large so that it is easy to assemble and install. The diameter of the pipes on solar collectors for radiator welding should be smaller than that of the pipes for coolant input and output.

From plastic and metal-plastic pipes

How to make a solar collector with your own hands, having plastic pipes in your home arsenal? They are less effective as a heat storage device, but are several times cheaper than copper and do not corrode like steel.

The pipes are laid out in a box in a spiral and secured with clamps. They can be coated with black or selective paint for greater effectiveness.

You can experiment with pipe laying. Since pipes bend poorly, they can be laid not only in a spiral, but also in a zigzag. Among the advantages, plastic pipes can be easily and quickly soldered.

From the hose

To make a solar collector for a shower with your own hands, you will need a rubber hose. The water in it heats up very quickly, so it can also be used as a heat exchanger. This is the most economical option when making a collector yourself. A hose or polyethylene pipe is placed in a box and secured with clamps.

Since the hose is twisted in a spiral, natural circulation of water will not occur in it. To use a water storage tank in this system, it must be equipped with a circulation pump. If this is a summer cottage and little hot water is consumed, then the amount that flows into the pipe may be sufficient.

From cans

The coolant of a solar collector made from aluminum cans is air. The cans are connected to each other to form a pipe. To make a solar collector from beer cans, you need to cut off the bottom and top of each can, dock them together and glue them with sealant. The finished pipes are placed in a wooden box and covered with glass.

Basically, an air solar collector made from beer cans is used to eliminate dampness in the basement or to heat a greenhouse. Not only beer cans, but also plastic bottles can be used as a heat storage device.

From the refrigerator

You can make your own solar water heating panels from an unusable refrigerator or the radiator of an old car. The condenser removed from the refrigerator must be rinsed thoroughly. Hot water obtained in this way is best used only for technical purposes.

Foil and a rubber mat are spread on the bottom of the box, then the capacitor is placed on them and secured. To do this, you can use belts, clamps, or the fastening with which it was attached in the refrigerator. To create pressure in the system, it would not hurt to install a pump or aqua chamber above the tank.

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.

Strength of the heating element for heating water

There are rumors in certain circles that flat heating elements are much more durable than vacuum ones, this is quite simple to explain: a flat element for heating water is a single, uniform panel. By its appearance, a flat heater shows that it is more resistant to mechanical stress. However, it is worth keeping in mind that even panels from world-famous manufacturers can be quite easily damaged. But in principle, natural disasters, huge hailstones, hurricanes that uproot trees, the fall of meteorites, which, in the end, can cause damage to the collector, are not such a frequent occurrence in everyday life to pay special attention to them.

It is much more practical to use vacuum solar collectors

If we look at the issue from the practical side of heating water, then it is much more practical to use vacuum solar collectors. This heating element consists of a large set of glass tubes. If for some reason one of the tubes is damaged, the principle of operation is such that it can be easily replaced with a new one. An additional advantage is that it is not necessary to replace a damaged element immediately upon its breakdown. The collector will continue to perform its functions even with damaged heating elements.

If the flat solar collector is damaged, it stops functioning and requires immediate troubleshooting - this is a rather unpleasant principle of its operation.

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.

Types of solar water heaters and their characteristics

Solar water heaters are a set of equipment for heating water using solar energy . Another name for these devices is solar collectors. Unlike photovoltaic panels, which use sunlight to produce electricity, solar heaters immediately receive thermal energy, which they transfer to the coolant (water, antifreeze, etc.).

They form a whole system consisting of the following elements:

Collector. A panel that receives thermal energy and transfers it to the coolant.
Storage tank. A container in which heated water is accumulated and the cooled coolant is replaced by a newly heated flow.
Heating circuit. A conventional radiator system or underfloor heating that utilizes coolant energy. In some types of system, the heating circuit is not included in the volume of the collector system, receiving energy in a storage tank, which in this case is a heat exchanger.

By type of circulation

The circulation of the coolant allows you to receive thermal energy in return for that released into the internal atmosphere of the house. There are two types:

Natural. It uses heated layers of liquid to move upward and replace them with colder layers. It does not require any devices or the use of electricity, but depends on many factors - the relative position of the collector, storage tank and other elements of the system, temperature, etc. Fluid movement is unstable and can wax and wane.
Forced. The flows are directed using a circulation pump. A stable mode arises with a constant flow rate, which allows for stable heating of the house.

Forced circulation is more efficient and allows the system components to be placed in the most convenient order, without paying attention to differences in heights and volumes.

By collector type

There are collector designs that have different efficiencies, capabilities, and methods of heat transfer. Among them:

Open . Flat, long trays or troughs made of black plastic in which water circulates. The efficiency of open collectors is very low, but their simplicity and low cost contribute to their popularity. Used to heat water for a summer shower or swimming pool.
Tubular (thermosyphon) . The main element is a coaxial tube with a vacuum layer between the outer layers, which reliably insulates the contents of the tubes. The design is effective, but expensive and cannot be repaired.
Flat . These are closed containers with a transparent top panel. The inner surface is covered with a layer of thermal energy receiver, which transfers it to water, which moves inside the tubes soldered to the receiver. A simple and effective design, in which, for greater effect, a vacuum is sometimes created for thermal insulation.

How effective the solar water heating system will be depends on which collector is installed in the system and how well it fits into the external conditions of the region - climate, weather, number and duration of sunny days .

By type of circulation circuit

Open – used to provide hot water to residential premises. The coolant in this case is water, which is used for various household needs and, accordingly, it no longer gets back into the circuit.
Single circuit system - used for heating a house. The coolant heated in this way is used as an additive to the coolant that was heated by the traditional method. In this case, the heated coolant passes into the heating system, after which it is again transferred to the receiving tank and to the collector.
The dual-circuit heating system is the most versatile. It is possible to use it for heating in winter or for water supply.

Double-circuit water supply and heating system

You can also choose one of the possible coolants - water, oil or antifreeze. After the collector, the coolant passes through a heat exchanger, in which heat is transferred to the second circuit. The second coolant used is already used for its intended purpose - for heating or water supply.

Coolant

For such water heaters, various coolants are used: antifreeze, lubricating fluid and water.

Application

Solar systems are gradually gaining popularity. With their help they solve many problems:

Heating the liquid to the required temperature.
Increased heating system performance.
Water heater for the pool, for a summer shower.
Heating liquid for other needs.

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.

How to choose a solar collector of the required power

If you want the heating system of your home to cope with the task of maintaining a comfortable temperature in the rooms, and hot and not lukewarm water flows from the taps, and at the same time you plan to use a solar collector as a heat generator, you need to calculate the required power of the equipment in advance.

In this case, it will be necessary to take into account a fairly large number of parameters, including the purpose of the collector (DHW, heating or a combination of both), the heat needs of the facility (the total area of heated premises or the average daily consumption of hot water), the climatic features of the region, and the features of the collector installation.

In principle, making such calculations is not so difficult. The performance of each model is known, which means you can easily estimate the number of collectors required to provide heat to your home. Companies involved in the production of solar collectors have information (and can provide it to the consumer) about changes in the power of the equipment depending on the geographic latitude of the area, the angle of inclination of the “mirrors,” the deviation of their orientation from the south direction, etc., which allows making the necessary adjustments when calculating collector performance.

When selecting the required collector power, it is very important to achieve a balance between the shortage and excess of generated heat. Experts recommend focusing on the maximum possible capacity of the collector, i.e. using the indicator for the most productive summer season in the calculations. This goes against the desire of the average user to take equipment with a reserve (i.e., calculate according to the power of the coldest month) so that there is enough heat from the collector even on less sunny autumn and winter days.

However, if you follow the path of choosing a solar collector of increased power, then at the peak of its performance, i.e. in warm sunny weather, you will face a serious problem: more heat will be produced than consumed, and this threatens overheating of the circuit and other unpleasant consequences . There are two options for solving this problem: either install a low-power solar collector and connect backup heat sources in parallel in winter, or purchase a model with a large power reserve and provide ways to discharge excess heat in the spring-summer season.

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;
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.)
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;

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.

Temperature division of water heating equipment

The consumer is offered a lot of different device options, but their main difference lies in the temperatures they achieve. According to this principle, they are made into three main types of collectors:

The first is low temperatures (they give low temperatures up to 50 degrees Celsius); the main calculation of application is heating a pool or other options when there is no need to heat the water very much.
Next come medium temperature collectors (they raise the temperature from 50 to 80 degrees) the main calculation of the application is for heating industrial buildings and residential premises.

Medium temperature collectors are used for heating industrial buildings and residential premises.

The third type is high temperature collectors (used in industry to generate electricity with subsequent distribution to the central electrical network).

Let's sum it up

In conditions of a total rise in prices for utilities, it is possible to use alternative methods of heating premises and heating water for household needs. In other countries, solar collectors have been used for heating for quite some time.

If you don't want to pay a lot of money for an industrial water collector, you can assemble it yourself using scrap materials. Do you want a design that is more solid and can actually meet your hot water needs and heat your home? Then you will have to visit a hardware store and prepare for assembly more thoroughly: purchase vacuum flasks, special tubes, sheets of glass or polycarbonate, and other components.

Cutting and stripping copper pipes for solar collector

When you decide which system is optimal, take into account: solar collectors, like any technical solution, have pros and cons that must be taken into account.

Pros and cons of a solar system

Among the positive aspects there are

environmentally friendly type of energy received free of charge;
reduction in utility costs for centralized water heating up to 40-50%;
short payback period;
the ability to heat water for household needs and heat small rooms in winter;
wide choice of materials, ease of assembly of structures.

Negative points include

labor costs for creating a light collector;
a decrease in efficiency in winter, which makes it almost impossible to use such systems in northern latitudes;
preventive maintenance and cleaning are required;
in cold weather it is necessary to use antifreeze, which entails additional costs.

Video on the topic:

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.

Operating principles of heating manifolds

One of the main designs of solar heating collectors are vacuum-type devices. Based on the name, it is obvious that such devices will collect radiant solar energy and transfer it to heat water or other coolant. This is actually the case in reality.

Autonomous heating systems incorporating solar collectors consist of the following main components:

The solar heating collector itself is a device that is placed in direct sunlight and serves to heat the coolant,
Heat exchange circuit: a pipeline system through which hot coolant moves, gradually transferring its heat to heated rooms,
Thermal accumulator: This is a water tank in which heated water is stored for future use.

So, the solar collector, consisting of pipes containing not yet heated coolant, is exposed to direct sunlight. The coolant fluid (usually water, but possibly special antifreeze) enters the collector, is heated there and transferred to the heat exchange circuit, which is mounted inside the heat accumulator. The heated coolant, moving inside the pipelines of the heat exchange circuit, heats the water in the heat accumulator. The heated water is stored in a tank with a heat accumulation function until it becomes necessary to use it, for example until it is supplied to the circuits of the home heating system and heating radiators or to the domestic hot water supply circuits, for example for washing.

Water supply circulation in the heating manifold

Since solar energy acts on the collector completely free of charge, the system at any time has heated water, which is heated by a constantly circulating coolant.

Naturally, the heat accumulator tank must have excellent thermal insulation, which helps maintain the temperature of the heated water for as long as possible. This will prevent the water temperature from dropping at night when there is no solar heating or during periods of cloudy weather. To ensure uninterrupted operation of such a system on very cloudy or rainy days, an ordinary electric water heater can be installed in the heat accumulator tank.

In order for the coolant to constantly transfer the heat of the sun's rays to heat the water, it must constantly circulate. In systems with solar collectors, the circulation of the coolant liquid can be forced (supplied by pumps) or natural (smotek).

Myth one: flat-plate collectors are stronger than vacuum ones

Solar collectors - vacuum (left) and flat (right)
High-quality flat collectors are quite durable and can easily withstand hail and similar external influences. But, of course, you can break them if you want. The same can be said about quality vacuum manifolds. In practice, replacing glass tubes with installed vacuum manifolds is quite rare, since quality tubes are very durable and designed to last a long time. Pay attention to the video below, which shows a vacuum tube being tested for strength with a piece of ice, simulating hail. This is a case in point.

And here is the same example using a steel ball.

It is also worth remembering that if a flat plate collector becomes damaged, it usually needs to be replaced, which is an expensive and difficult task. If several glass tubes of the vacuum manifold are damaged, it will still continue to work, and the tubes can be replaced later. Typically, when installing vacuum manifolds, provision is made for how the tubes will be replaced if they are damaged and have reached the end of their normal service life (15 years).