A simple DIY thermosiphon solar collector without a pump. Solar collectors for heating How a solar collector works

Content

The modern market offers a wide variety of heating devices, but their cost can be too high. Especially if you need not one, but two or three heating tanks. Utility prices are constantly rising, people are forced to look for ways to save on heating and hot water heating. There is an alternative source of heating, so you can make a solar collector with your own hands, which will use the sun's energy for home needs. This is an economical option for heating premises and providing residential buildings with warm water.

Solar collector for heating a house

You can find similar equipment in domestic stores, but the price will be even higher than the amount spent on installing a conventional heating system. You can make a solar collector yourself using available materials that can always be found in the arsenal of a thrifty owner: tin sheets, cans, plastic bottles, polycarbonate sheets, glass tubes, etc.

Principle of operation

Homemade collectors are perfect for heating, heating water in small houses, cottages, and heating swimming pools. Having decided to assemble such a unit at home with your own hands, you need to remember the physical laws and understand the principle of its operation:

• The receiving device absorbs (absorbs) solar energy: copper or glass surfaces of black or dark color can be used as such. It is these materials that have greater absorption and are optimal for heating water or other liquids.
• The heat from the absorber is transferred to a tank with a coolant: water, antifreeze, or other special liquid that will heat your home.
• The coolant is supplied through pipes to radiators and used for household needs (hot water in the kitchen, bathroom).

Summer version of the design

You can make a solar collector with your own hands quite quickly, it is not a very difficult job. To use it in the countryside, in the summer, you do not need complex schemes and special equipment:

• If water is needed only outside (outdoor shower, hot water for laundry, swimming pool, washing dishes, other household needs), the tank is also installed outside.
• When water is needed in the house, the tank will be installed inside.
• In such a system, natural circulation of liquid occurs, so the tank must be installed 8-10 centimeters above the battery level.
• To connect the tank to the battery (absorber), you will need pipes of a certain diameter.
• If the system is large, it is better to install a pump that will increase the movement of the coolant.

Important! If you plan to use a solar collector to heat water not only in summer, but also in the cold season, the scheme will be different; you need to take into account some nuances.

Is it possible to use a solar collector in winter?

To use the device year-round, you need to learn more about how the solar collector works in winter. The main difference is the coolant. Since water can freeze in the pipes of the circuit, it must be replaced with antifreeze. The principle of indirect heating works with the installation of an additional boiler. The following is the diagram:

• After the antifreeze heats up, it will flow from the battery located outside into the coil of the water tank and heat it.
• Then warm water will be supplied to the system, and cooled water will be returned back.
• It is necessary to install a pressure sensor (pressure gauge), an air vent, and an expansion valve to relieve excess pressure.
• As in the summer version, to improve circulation it is necessary to provide a circulation pump.

Need to know! There are different collector designs that you can make yourself; they differ in design features and have advantages and disadvantages.

Device and types

Conventionally, these systems can be classified into two types:

• liquid (which we talk about in this material);
• air solar collectors, which use heated air rather than liquid.

They are also divided according to efficiency, because they provide different heat transfer. It depends on the materials used to make the battery and its area. The optimal location for the absorber is the roof:

• receives the maximum amount of sunlight,
• has a large area
• The battery installed on the roof does not take up any useful space and does not interfere with anyone.

The design of the solar collector can be of several types, the main:

• vacuum heating manifold, which has the most complex design. Vacuum solar collectors are excellent for heating rooms, heating water at any time of the year, they will completely provide a small house or cottage;
• A flat solar collector can be liquid or vacuum. This is the most common type because it is quite easy to install, yet it is efficient and can provide the house with the necessary amount of heat for heating the premises, and water for household needs;
• thermosiphon - glass or metal tubes are used as an absorber;
• tubular - the simplest type that can be made for a summer residence; it is quite primitive and not suitable for use in winter.

We are interested in a design that ensures the availability of hot water and heating in the house at any time of the year; we will focus on two optimal options, consider the design of a vacuum solar collector and a flat one.

Flat-plate collector

This is the most common type of collector that you can make yourself. Well suited for use in the warm season for heating water; in winter the efficiency decreases.

The design feature is as follows:

• the body has a flat rectangular or square shape, made of metal or other material with a high thermal conductivity, coated with black paint;
• inside there is a plate in which a coil made of a copper tube of small cross-section is laid;
• coolant circulates through the tubes: water, propylene glycol, antifreeze, and other suitable liquids;
• also, thermal insulation material is placed inside the housing, which minimizes heat loss;
• When assembling a collector of this type, you need to stock up on a sheet of polycarbonate or glass, which will serve as a cover and perform two functions: prevent the penetration of debris and precipitation, and enhance heating.

Important! Before assembling the structure, you need to check the seams for tightness in order to prevent moisture, dust from entering the unit, and warm air from venting.
Care tip! To avoid a decrease in efficiency, you need to regularly wipe the glass surface from dust and dirt.

Vacuum manifold

For water heating, vacuum-type solar collectors can be used. Thanks to their design features, they are more powerful: they are able to generate thermal energy, which is enough to heat water and heat rooms.

Design Features:

• Tubes that are placed in flasks with the air pumped out allow to minimize losses;
• the tubes are covered on top with an absorption material that absorbs light energy, and inside they are filled with antifreeze (refrigerant);
• the ends of the tubes are connected to a pipe through which the coolant passes;
• when heated, the antifreeze boils and turns into steam, which, in turn, rises and heats the coolant;
• This design has a drawback: if at least one tube fails, repair becomes quite problematic, since they are connected in series. All the “internals” will have to be replaced.

Such an air-air solar collector for heating will be more efficient and suitable for maintaining the temperature in the system in any season. Although in cold weather, the efficiency of a working collector may decrease slightly due to short daylight hours and low light activity.

Care tip! Pay attention to the inner surface of the water storage tank; it becomes covered with scale over time and needs cleaning. The frequency depends on the water quality in the area.

Please note: it is unrealistic to make vacuum tubes with pumped-out air in home-made conditions; you will have to buy them. This will slightly increase the costs of installing this type of collector.

Making a homemade solar collector

If you are interested in the question of how to make a solar collector, consider main stages of manufacturing flat structures:

• First you need to calculate the dimensions of the future heater, based on the area of ​​the heated room. They will also depend on the level of solar activity in a particular region, the location of the house, the terrain, the materials used and other factors. But the starting point is still the surface area on which it will be installed.
• Consider what the absorber (receiver) will be made of. For these purposes, you can use copper and aluminum tubes, steel flat batteries, a rolled rubber hose, etc.
• The receiver must be painted black.
• Then you need to make the collector body; various materials are suitable for this. The most common is wood, but glass can be used. If you have old glazed windows, this is an ideal option.
• Between the bottom of the housing and the absorber, you need to lay a thermal insulation material (mineral wool or polystyrene foam), which will prevent heat loss.
• Cover the entire area of ​​the heater with a metal sheet (made of aluminum or thin steel), which will enhance the effect.
• Lay the coil pipes on top, attach them to a metal sheet using construction staples or other means, and bring the ends of the coil out.
• Thermal solar collectors are covered on top with light-transmitting material, most often glass. You can use transparent polycarbonate, which is more practical: resistant to mechanical shock and easy to maintain.
• The water tank should be covered with insulating material or painted with black paint to slow down the cooling process of the water.
• Mount the heating element in place and connect it using pipes to a storage tank with water.
• Carry out startup work, check the wiring along the entire length for leaks due to poor-quality connections.

Important! For better heat transfer, it is necessary to leave a distance of approximately 10-15 mm between the glass and the heating tubes. All joints must be well sealed.

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.

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.

So, the question on the agenda is: how to assemble and make a solar collector with your own hands. If there is a question, it must be resolved, preferably positively. This guide describes the process of creating a solar collector with your own hands, which can provide a summer resident with a full-fledged hot shower. The heart of the collector is a copper coil in which water circulates. When heated, the water enters the upper part of the tank, and cold (cooled) water from the lower part of the tank returns to the collector for additional heating. In this way, natural circulation occurs without the use of a pump. In order to increase the heating area of ​​the collector, special plates are attached to the coil, which absorb all the heat from the surface of the collector and transfer it to the heat exchanger. And sealing and insulating the box will not allow it to lose the heat received.

Stage one: “Making a coil with your own hands”

To create a coil with our own hands, we will need 16 meters of soft copper pipe d10 mm. It is usually sold in coils. This tube is easy to bend, so we use it. Schematically the coil will look like this:

For fixation, the coil is attached to a base made of 5 mm thick plywood measuring 800 by 1800 mm. Therefore, the first thing we do is cut out the appropriate sheet of plywood. All coil sections should be installed at a slight angle (about 5°). If you lay the pipe strictly horizontally, the system will not work. (without pump) We must attach special templates to the plywood. With their help it is much more convenient to lay the coil. In addition, they will support and fix the structure. We make templates from the same plywood 5 mm thick:

We need to make 14 templates No. 1 and No. 2. Templates need to be attached to the base according to the diagram:

We start installing templates from the lower left corner. First, in steps of 100 mm Templates No. 2 are installed. (distance from edge 50mm)

Then templates No. 1 are installed between them at an angle of 5 degrees relative to the center of the collector. We attach the templates with nails or 7-9 mm screws. (at least 2 for each template) We begin laying the copper pipe. We attach the pipe to the plywood. Leave the end 10 cm beyond the boundaries of the plywood. We press the tube to the template and fix it with a bracket. We pull the tube to the next template located on the other side. We make sure that the tube is positioned exactly at an angle of 5° without “burrs” or “sagging”. We fix it in several places. Having reached the turn, we lay the tube between the templates and fix it. So gradually turn by turn. After the coil is assembled, check the strength of the fixation to the base, and most importantly, the angle of inclination of each section. Remember that there should be no sagging on straight sections, otherwise the system will not work.

Stage two.“Making plates with your own hands”

To make plates with our own hands, we will need an aluminum sheet 0.4-0.5 mm thick. Cut it out according to the drawing:

If you have small pieces, then it's okay. Instead of one plate 440 mm long, you can make two 220 mm long, or three 146 mm long. The plate should fit snugly to the base and “hug” the tube as tightly as possible. After the shape is cut out, you need to give the area indicated by the dotted line the shape of a tube. To do this, we make a wooden template according to this scheme:

After the shape is created, use a hammer to drive a steel block into the recess of the mold:

It is necessary to make 15 such plates. After the plates are made, you need to attach them to the plywood, on top of the coil. Before installing the plate on the tube, lubricate it with heat-conducting paste for a better effect. Then we press it to the pipe and fix it with a furniture stapler:

To achieve even greater productivity, an aluminum sheet 440 mm long and 40-50 mm wide can be laid under the tube. This must be done before installing the coil, in the area between the templates:

After all the plates are laid, we paint them with heat-resistant matte black paint. The ideal option would be to sandblast before painting, so that the surface of the plates becomes rough and better accepts sunlight.

Stage three:“Do-it-yourself solar collector - assembly”

To assemble the solar collector, we need a frame. It is made according to the dimensions of the base for the coil:

To make it we use 20x70 mm timber. (two sections 1840 mm long and two 800 mm long). We fasten them. Now we cut out a piece of 1840mm by 840mm from moisture-resistant plywood and attach it to the frame. We have a box. Next, we install an additional frame made of 20x20mm timber. It is needed in order to attach a base with a coil to it. In the diagram, timber 20x70 is indicated in orange, and 20x20 in blue:

Now we need to put everything together. We lay the insulation on the bottom of the box. Its size is 760 mm by 1760 mm. The thickness of the insulation should be equal to the height of the beam 20x20, i.e. 20 mm. After the insulation, we lay foamed polyethylene measuring 800 by 1800 mm. And after that we lay the base with the coil. In cross-section, the entire structure looks like this:

Using 15 mm self-tapping screws, we attach the base to the box, or rather to a 20x20 beam. Now let's start insulating the side walls. To do this, we use insulation 10 mm thick and 40 mm high. It must be reinforced with staples around the entire perimeter. The next stage is glazing. We will need glass 1840 by 840
mm. Before installing it, we apply a layer of silicone around the perimeter of the box. Then we install the glass itself. Once again, we additionally apply silicone to the junction of the glass and the box. We will fasten the glass using an aluminum corner of any of 4 sizes: 20x30, 20x40, 30x30 or 30x40. In total, 5300 mm of corner will be required.

Stage four:“Do-it-yourself solar collector - connection»

For maximum effect, the solar collector should be installed at an angle of 90° to the angle of incidence of the sun's rays. The angle of the sun's rays depends on the latitude of the area where the collector is installed. In addition, this angle changes throughout the year. The best option is to make a special stand where you can adjust the angle of the solar collector. It is enough to change this angle once a month to obtain optimal results. You can see a diagram of such a support below:

But very often a situation arises that it is impossible to change the angle of inclination every month. This happens if the collector is installed on the roof. In this case, it is necessary to determine the optimal angle for the entire operating season and immediately install the collector at this angle during installation. When operating the collector in summer, it is recommended to install it 15-25° less than the latitude of the area. For example, Moscow is located at latitude 55.75°. This means that the optimal tilt angle will be from 30° to 40°. This collector must be connected to a container with a volume of 30 liters. The container should be located above the highest point of the collector. But this distance should not exceed 1 meter, but not less than 30-40 cm. Connections between the collector and the tank can be made using polypropylene pipes d20 mm. To do this, you need to solder an adapter to the copper tube, and then attach the pipe to it. At the same time, try to avoid bends, and carry out transitions using half-bends (no more than 2 for direct and reverse transition). The outlet from the top of the manifold should be connected to the top of the tank, and the outlet from the bottom of the barrel should be connected to the inlet at the bottom of the manifold.

You also need to supply cold water to the container. You can install a regular toilet siphon system in the cistern by installing a 30-liter float. But at the same time, with every second of taking a shower, the water will cool, so the simplest and most effective way is a manual faucet. This way, you use up all 30 liters of hot water, and only then fill the tank again. If you want to quickly get a small amount of hot water, then fill the tank not completely. Please note that 30 liters is a sufficient amount for clear weather in the Moscow region. If the weather is cloudy or the air temperature is below 8 C, then do not fill the tank completely. If there is heavy cloudiness and the sun is not visible, fill the tank with only 20 liters of water. And if cloudiness is accompanied by low air temperature - then 15 liters. These rules work in the conditions of the Moscow region and the central part of Russia. For the Leningrad region, the maximum tank volume is 25 liters, and for Kuban - 35 liters. Do not forget that the storage tank must also be insulated.

Almost every owner of a private home has to face problems with heating residential premises and obtaining hot water. Today, there are many different systems that allow you to successfully solve these problems. Alternative heating sources deserve special attention, in particular a collector that uses solar energy as fuel. This unit is extremely easy to assemble and profitable to use.

The average efficiency of homemade solar collectors reaches 50-60%, which is a very good indicator.

Professional units have an efficiency of about 80-85%, but you need to take into account the fact that they are quite expensive, and almost everyone can afford to purchase materials for assembling a homemade collector.

The power of an ordinary solar collector will be enough to heat water and heat living rooms.

In this regard, everything depends on the design features, which are determined and calculated individually.

Assembly of the unit does not require difficult-to-handle, hard-to-reach tools or expensive materials.

Tools for DIY solar collector assembly

1. Hammer.
2. Electric drill.
3. Hammer.
4. Hacksaw.

There are several varieties of the design in question. They differ from each other in efficiency and final cost. Under any circumstances, a homemade unit will cost an order of magnitude cheaper than a factory model with similar characteristics.

One of the most optimal options is a vacuum solar collector. This is the most budget-friendly and easiest-to-use option.

The units in question have a fairly simple design. In general, the system includes a pair of collectors, a front chamber and a storage tank. The operation of the solar collector is carried out according to a simple principle: as the sun's rays pass through the glass, they are converted into heat. The system is organized in such a way that these rays are not able to leave the confined space.

The installation operates on the thermosiphon principle. During the heating process, the warm liquid rushes upward, displacing cold water from there and directing it to the heat source. This allows you to even avoid using a pump, because... the liquid will circulate on its own. The installation accumulates solar energy and stores it within the system for a long time.

Components for assembling the installation in question are sold in specialized stores. At its core, such a collector is a tubular radiator installed in a special wood box, one of the edges of which is made of glass.

To manufacture the mentioned radiator, pipes are used. The optimal material for making pipes is steel. The inlet and outlet are made from pipes traditionally used in the installation of water supply systems. Typically ¾ inch pipes are used, 1 inch products also work well.

The grate is made from smaller pipes with thinner walls. The recommended diameter is 16 mm, the optimal wall thickness is 1.5 mm. Each radiator grille must include 5 pipes, each 160 cm long.

Important nuances of assembling a collector with your own hands

The first stage is assembling the box. To assemble the previously mentioned box, wooden boards about 12 cm wide and 3-3.5 cm thick are used. The bottom is made of hardboard or plywood sheet. The bottom must be reinforced with slats measuring 5x3 cm. Select the length of the slats according to the size of the bottom.

The second stage is insulation of the box. The box needs high-quality insulation. The best and most convenient option to use is foam boards. Mineral wool also works well. The insulation is placed on the bottom of the box.

The third stage is the arrangement of the radiator box. The laid insulation must be covered with a layer of galvanized sheet metal. Clamps are used to connect the radiator and the laid sheet of metal. Pre-paint the radiator pipe and metal decking with matte black paint.

The outside of the box is painted white, and the glass is sealed using compounds specially designed for such tasks. This will minimize heat loss. The pipes are connected in the standard manner using tees, couplings, and angles. The pipes used in assembling the manifold are connected manually without much effort.

The fourth stage is the preparation of the storage tank. A tank is responsible for the accumulation of heat in the system under consideration, the capacity of which can be in the range of 200-400 liters. Select the specific volume based on your personal water needs. The tank can be made from a barrel. If you can't find a suitable barrel, use pipes.

The tank needs insulation. It is best to install it in a box made of plywood sheets or wooden boards, and fill the space between the walls of the box and the container with sawdust, foam plastic or other heat-insulating material.

The fifth stage is the preparation of the fore-chamber. The system in question includes a unit called an advance chamber. The main function of this device is to pump up the constant excess pressure required for the full operation of the system based on the solar collector. The anterior chamber is made from a suitable container of 35-45 liters. A can is perfect. Additionally, the unit is equipped with a feeding device to automate the operation.

Step-by-step instructions for assembling the unit

Coolant circulation diagram

The first stage is the installation of the drive and front camera. The mentioned units are located in the attic of the house. Make sure the ceiling at the installation location can support the weight of the water containers. Install the front camera next to the drive. Do this so that the liquid level in the fore-chamber is approximately 100 cm higher than the water level in the storage tank.

The second stage is choosing a place to install the solar heater. The unit is fixed on the southern wall of the building. It is important to maintain the correct slope of the heater to the horizon. The optimal value is 45 degrees. The collector must be attached to the house so that the solar panels look like an extension of the roof.

The third stage is the connection of individual elements. To complete this task, you need to buy inch and half-inch steel pipes. You will use half-inch ones to connect high-pressure elements of the system - from the water inlet to the anterior chamber. Inch pipes are used in the low-pressure part.

It is important that the connections are airtight; air pockets are unacceptable in this case.

The pipes must first be painted white or another light color. A layer of heat-insulating material is fixed on top of the paint. In this case, foam rubber is optimal. A layer of polyethylene is wound over the insulation, and then a woven tape. Finally, the pipes are painted white again.

The fourth stage is filling the system with liquid. Water must be supplied through special drainage valves installed at the bottom of the radiators. This will avoid the formation of air locks. When water begins to flow from the drainage, the operation can be considered complete.

The fifth stage is connecting the front camera. This unit must be connected to a water supply inlet. After connection, open the flow valve. You will see that the amount of water in the forechamber will begin to decrease.

The advantage of such a solar collector, assembled with your own hands, is that it can heat water even in cloudy weather.

At night, the air temperature becomes lower than the temperature of the heated water. Under such conditions, the collector will begin to heat the environment and generally operate in the reverse mode. To avoid this, the system is equipped with a valve that prevents the possibility of reverse circulation. It will be enough to simply turn off this valve in the evening, and the energy will be stored in the system.

If the thermal conductivity of the collector is not high enough, it can be increased by adding sections. The design will allow you to do this without any difficulty.

Thus, there is nothing difficult in assembling a solar heater yourself. Such work also does not require large financial investments, but it is strongly recommended to buy only high-quality materials from well-known manufacturers. Approach your work with maximum responsibility, do not violate the recommendations given, and you will receive an excellent source of heat and hot water, powered by free energy. Good luck!

Video - DIY solar collector

Energy resources. Free solar energy will be able to provide warm water for household needs for at least 6-7 months a year. And in the remaining months, it also helps the heating system.

But the most important thing is that a simple solar collector (unlike, for example, from) can be made independently. To do this, you will need materials and tools that can be purchased at most hardware stores. In some cases, even what you can find in a regular garage will be enough.

The solar heater assembly technology presented below was used in the project "Turn on the sun - live comfortably". It was developed specifically for the project by a German company Solar Partner Sued, which professionally sells, installs and services solar collectors and photovoltaic systems.

The main idea is that everything should be cheap and cheerful. To manufacture the collector, fairly simple and common materials are used, but its efficiency is quite acceptable. It is lower than that of factory models, but the difference in price completely compensates for this disadvantage.

The sun's rays pass through the glass and heat the collector, and the glazing prevents heat loss. Glass also prevents air movement in the absorber; without it, the collector would quickly lose heat due to wind, rain, snow or low outside temperatures.

The frame should be treated with an antiseptic and paint for exterior use.

Through holes are made in the housing to supply cold liquid and remove heated liquid from the manifold.

The absorber itself is painted with a heat-resistant coating. Regular black paints begin to flake off or evaporate at high temperatures, which leads to darkening of the glass. The paint must be completely dry before you attach the glass cover (to prevent condensation).

Insulation is placed under the absorber. The most commonly used is mineral wool. The main thing is that it can withstand fairly high temperatures during the summer (sometimes over 200 degrees).

The bottom of the frame is covered with OSB boards, plywood, boards, etc. The main requirement for this stage is to make sure that the bottom of the collector is reliably protected from moisture getting inside.

To secure the glass in the frame, grooves are made, or strips are attached along the inside of the frame. When calculating the size of the frame, it should be taken into account that when the weather (temperature, humidity) changes during the year, its configuration will change slightly. Therefore, a few millimeters of margin are left on each side of the frame.

A rubber window seal (D- or E-shaped) is attached to the groove or strip. Glass is placed on it, onto which a sealant is applied in the same way. This is all secured on top with galvanized sheet metal. Thus, the glass is securely fixed in the frame, the seal protects the absorber from cold and moisture, and the glass will not be damaged when the wooden frame “breathes.”

The joints between sheets of glass are insulated with sealant or silicone.

To organize solar heating at home you will need a storage tank. The water heated by the collector is stored here, so it is worth taking care of its thermal insulation.

The following can be used as a tank:

• non-functioning electric boilers
• various gas cylinders
• barrels for food use

The main thing is to remember that a sealed tank will develop pressure depending on the pressure of the plumbing system to which it will be connected. Not every container can withstand pressure of several atmospheres.

Holes are made in the tank for the entry and exit of the heat exchanger, the entry of cold water, and the intake of heated water.

The tank houses a spiral heat exchanger. Copper, stainless steel or plastic are used for it. Water heated through the heat exchanger will rise upward, so it should be placed at the bottom of the tank.

The collector is connected to the tank using pipes (for example, metal-plastic or plastic) carried from the collector to the tank through a heat exchanger and back to the collector. It is very important here to prevent heat leakage: the path from the tank to the consumer should be as short as possible, and the pipes should be very well insulated.

The expansion tank is a very important element of the system. It is an open reservoir located at the highest point of the liquid circulation circuit. For the expansion tank, you can use either a metal or plastic container. With its help, the pressure in the manifold is controlled (due to the fact that the liquid expands from heating, pipes may crack). To reduce heat loss, the tank must also be insulated. If there is air in the system, it can also escape through the tank. The reservoir is also filled with liquid through the expansion tank.

This publication presents the results of extensive research by blogger Sergei Yurko. Shown are 3 solar collectors made by a craftsman with his own hands and the most effective of them is the so-called 3-film collector, it heats water up to 60 degrees. There is a simpler 2 film, and it is capable of bringing water to 55 degrees. The simplest and cheapest is 1 film, but it only provides heating to 35 or 40 degrees.

The cost of one square meter of these primitive collectors is approximately a thousand times cheaper than their factory counterparts, and therefore the question arises: what is so good about branded collectors that they cost a thousand times more than primitive ones, which anyone can make with their own hands in a few hours, spending meager money.

We will compare simple collectors with expensive factory models in terms of efficiency, economic feasibility and other characteristics. And this comparison is not always in favor of factory devices. Video on the topic: let's make the simplest solar collectors and see what they can do. We will also find out in what cases it makes sense to abandon cheap solar heat from these primitive structures in order to pay hundreds or thousands of times more to get the same effect from more expensive devices.

The personal interest of the author of the video in the topic is based on the assumption that factory solar collectors are an evolutionary dead end for solar thermal energy, since, for example, solar panels have fallen in price by more than a hundred times over the past few decades and the graph shows the process of price decline.

The idea arises that the evolution of solar collectors has gone the wrong way and therefore it makes sense to return to the simplest technologies.

The black film is the only thing that a 1-film primitive collector consists of, that is, water is poured onto the film and it is obvious that during the sun this water will heat up. You can buy it at the bazaar in any city. The master purchased three square meters for 15 hryvnia. The cost of the collector is 15 euro cents per square meter.

But it makes sense to add another one - a transparent film that will cover the surface of the heated water. The heating temperature increases radically as the second film stops the evaporation of water. It is sold at any market for greenhouses and because of this second layer, the cost of the collector increases to 35 euro cents per square meter.

But there is also a 3-film option and the additional film is also transparent; it will increase the cost of the collector to 55 euro cents per square meter.


Function 3 of the film is the same as that of the glass of a factory flat collector, that is, a layer of air several centimeters thick is formed between the glass and the black absorber; the air acts as a heat insulator.

How many films are needed to heat water well?

Experimental measurements gave unexpected results, since it turned out that in our case the result of using the third film is not as effective as in the case of a factory flat collector - the water heating temperature increases, but only by a few degrees. Moreover, our three collectors may have different designs. For example, 2 film - transparent polyethylene film, sold at markets in the form of a sleeve. Water is poured into the sleeve, and the role of the lower black film is played by the black surface of the roof of a high-rise building.


A similar study, but with a sleeve made of black film rather than transparent. If the second film is black, this option is preferable only if there is good water circulation through the system. The collector heated 100 liters of water to 66 degrees. Several design complications can be seen, including a 3-centimeter thick polystyrene foam sheet. but experiments have shown that thermal insulation under the collector will increase the heating temperature, but not radically.

An experiment in August with heating water at an air temperature in the shade of 35 degrees showed that a film collector with good thermal insulation heated the water to 63 degrees and at the same moment another collector heated the water to 57 degrees, although there was no thermal insulation under it and its first film lay right on the ground.

Additional features of the DIY garden collector

It is also interesting to note that during rain, a single-film collector performs the function of collecting rainwater, which may be relevant for some houses and areas. In addition, 1 film and 2 film collectors can act as a cooling tower at night, that is, they remove heat from the water used for cooling systems. They can be used in a mode where water circulates through them during the day and needs to be heated. and at night the collector cools the water in the tanks. During the day, water from them is used to extract heat. As a result, it heats up. and therefore the next night it must be cooled again with collectors.

It is interesting to note that the height of water in sewers can exceed several centimeters. they are both solar collectors and a hot water tank. That is, they work like the well-known black barrel on a summer shower.

But it is obvious that after the sun disappears, the water in the collector cools down. For this case, a collector with three layers of film, in which the water cools slowly, may be interesting.

On the picture. The cost of factory-made thermal collectors is a thousand times more expensive than the home-made ones presented.

Statistics on measuring the efficiency of homemade and factory-made solar heaters

On August 1, I conducted an experiment to measure the performance of film collector 2. Throughout the sunny day, I measured the water temperature and entered it into a table.

In the following table there is an interpretation of the results obtained, in the column the amount of heat that the collector actually produced.


It is described in the photo note as calculated based on the results of temperature measurements. In another column is the amount of solar radiation that hit the solar collector. Moreover, it is important to note that it depends on the angle of the sun above the horizon, more precisely on the sine of this angle.

It is interesting that during this time period the heat production by the collector was greater than the amount of solar radiation. but there is no paradox if you pay attention to the temperature difference. At this time, the air temperature was higher than the water in the collector, and therefore it warmed up not only due to the absorption of solar radiation, but also due to heating from the warmer air. but at other time intervals the water was already warmer than the air. Moreover, the greater the temperature difference, the greater the heat leakage from the water into the surrounding air. the less useful heat the collector produces. We can conclude that once the water temperature reaches about 60 degrees, it will stop heating, since the mentioned heat leaks will equal the solar energy entering the collector.

The rightmost column of the table records the measured heating power of the collector per unit area; it can be compared with the column with the heating power of one square meter of a factory collector under the same conditions. Describes how to calculate powers. One square meter of a factory model has an advantage over the same area of ​​a homemade one only when working at high water temperatures. and if you need to heat water with a temperature above 60-70 degrees, then a makeshift collector will not be able to work at all. at the same time, 1 square meter of a homemade heat exchanger will produce noticeably more heat than one square meter of a factory-made one when the water temperature is lower than the ambient air temperature.

The results are explained by the energy characteristics of the 2 film collector.

And this is an assessment of the characteristics of other types of primitive heaters.

Approximate characteristics of factory flat-plate collectors presented in the passport.

On the Internet you can find such characteristics for almost any brand. The table shows that the branded heat exchanger has an advantage in this coefficient, due to which it is able to operate at high temperatures. but on the other hand, a homemade collector works much better than a factory one if you need to heat water at a temperature below air. For example, if you need to heat 10 degree water from an underground well during 30 degree heat. The fact is that it is more correct to call the coefficient not heat losses, but the heat transfer coefficient. Because if the water in the collector is colder than the air, then there is no heat loss in the collector, but on the contrary, additional heat enters it from the warmer air. This coefficient is interpreted so that if the temperature difference between water and air increases by 1 degree, then the heat exchange through each square meter of the collector increases by 20 watts.

This characteristic (optical efficiency) shows the efficiency of converting solar radiation into useful heat under conditions when the temperature of the coolant in the collector is equal to the ambient temperature. The note describes why the simplest collectors have this indicator slightly better than the factory ones. But this is the indicated efficiency of a new clean collector, and primitive ones are very sensitive to dirt. The text below describes how much dirt accumulates in them during use.

Dirt and bubbles in simple homemade manifolds

* A lot of different dirt comes into the water of a 1-film collector from the outside. In 2- and 3-film devices, this problem is expressed in a dust deposit on the top film, and after the rain or dew has dried, this dirt is grouped into opaque spots, which can very noticeably reduce the efficiency of the collector. But on the other hand, there are several simple ways to remove this dirt after rain.
* A lot of dirt also falls out of the water in the form of small flakes on the surface of the water or large flakes at the bottom. These precipitations intensify due to heating of the water.
* “White plaque” also accumulates (at the top of the 1st and bottom of the 2nd film), which significantly reduces the efficiency. It attaches to films very firmly, i.e. it cannot be removed with a stream of water (and it can be scrubbed off with great difficulty and not completely with a brush). Perhaps this is the precipitation of salts from heated water, perhaps these are the consequences of the decomposition of plastic films.
* Some of the dirt in the collector can be explained by polyethylene decomposition products due to UV radiation and high temperature. Typically, polyethylene decomposes into hydrogen peroxide, aldehydes and ketones. Basically, these are gases or liquids that are highly soluble in water. those. It seems they should not precipitate.
* The efficiency of the collector also decreases due to the large number of gas bubbles (up to several millimeters in diameter at the top of the 1st and bottom of the 2nd film), which are released when the water is heated (When heated, the solubility of gases in water decreases). It is interesting that when the collector is located on the ground, there are practically no bubbles on its 1st film (but they are on the bottom of the 2nd)
* Large bubbles may form under the 2nd film, as well as air in the folds. These areas quickly become foggy and this reduces efficiency.
* At the edges of the collector, the 2nd film may not adhere to the water: in such areas the bottom fogs up and therefore does not transmit solar radiation well.
* 3-film collectors may have fogging on the bottom of the 3rd film. This happens when the 2nd film is installed incorrectly (due to which steam from the collector can penetrate under the 3rd film) or due to its damage. In such cases, you need to install the 3rd film so that the wind slightly ventilates the space between it and the 3rd layer.

Contamination of sewer water due to the decomposition of polyethylene films

This decomposition will be due to simultaneous exposure to atmospheric oxygen, ultraviolet solar radiation and a temperature of 50-60 degrees. Polyethylene decomposes into aldehydes, ketones, hydrogen peroxide, etc.
When heated in the collector, each 1 cu. m of water, its polyethylene films will emit about 1 g of decomposition products (per 1 sq. m of collector there are about 100 g of the 1st and 2nd films, and during their service they will emit, according to very rough estimates, about 10 g of “products decomposition" and heat about 10 cubic meters of water). But it is not clear how much of this 1 mg/liter will go into water, and how much will fly into the atmosphere, precipitate at the bottom of the collector and hot water tank, turn into that “white coating” (which I talked about in the previous text), will not work out beyond the weight of polyethylene
In addition, it is unclear the beneficial effect on water purification due to its presence and heating in the collector (and there a lot of sediment falls out of it), as well as due to the presence of hot water in the tank. Thus, according to rough estimates, 0.1-0.5 mg/liter of polyethylene decomposition products will enter the water, which will be distributed among dozens of chemicals. substances with concentrations of 0.001-0.1 mg per liter of heated water. Since this is not far from the maximum permissible concentration of harmful substances, consultation with the SES will not be superfluous. For example, according to standard GN 2.1.5.689-98 “Maximum permissible concentrations (MAC) of chemicals in water bodies for domestic, drinking and cultural water use”:
– There is a limit of 13 pieces. aldehydes - MPC from 0.003 mg / liter to 1 mg / liter, for example, MPC for formaldehyde - 0.05 mg / liter, and the most stringent requirements for benzaldehyde - 0.003 mg / liter
– MPC of hydrogen peroxide – 0.1 mg/liter
– 3 pcs. exotic ketones also have restrictions with a maximum permissible concentration of 0.1-1.0 mg / liter

Conclusions:

1) If the water “stagnates” in the collectors, then the concentration of “decomposition products” in it will be several times or tens of times greater. Perhaps it is better to throw away such water.
2) It is advisable to use thinner films (they will produce fewer “decomposition products”).
3) Films should preferably be as stabilized as possible. For example, greenhouse is preferable to regular (not tinted) polyethylene; it is stabilized against the effects of UV radiation. Another example: high-density polyethylene degrades more slowly due to high temperature than low density.
4) The ratio of the collector area to the facility’s need (for hot water) is preferably as small as possible. That is, for example, with a daily requirement of 10 cubic meters. m of hot water, station with 50 sq.m. collectors produces water pollution (concentration of harmful substances) that is tens of times less than a station with 500 sq.m. collectors, including due to the lower temperature of water heating by collectors, which reduces the rate of polyethylene decomposition.
5) If the 2nd film of the collectors is black (and not transparent), then the water contamination should be several times less (since UV radiation penetrates only the top layer of the 2nd film).
6) You can think about this option for operating a solar station, when the collectors are heated
process water, which then transfers its heat through a heat exchanger to clean DHW water.

Which is better to use film for collecting solar heat - black or transparent?

The optical efficiency is noticeably reduced due to air bubbles and fogging of the second layer of the collector film. This means that the efficiency of the actually used device over its entire service life will be several tens of percent less. Therefore, it makes no sense to strive for expensive films with great durability, since after several months of use they will accumulate so much dirt that you will want to replace the films. Due to such problems with various dirt, we are inclined to believe that film 2 should still be opaque, but black.

This collector has a black film and there is no radical decrease in efficiency due to dirt. But it has a problem - the sun only heats the thin top layer of water. However, there are several solutions to the problem that will be obtained after research.

It is important to keep in mind that the wind increases the heat loss coefficient of primitive collectors, and in the case of single-film collectors, this influence of the wind can be radical, since heat loss from the collector increases due to water evaporation and can reach the point that even on a perfectly sunny day, but with strong winds and low humidity 1-film will be able to heat water only a few degrees above the ambient temperature. In addition, the coefficient k1 needs to be increased by several tens of percent if there is no thermal insulation under the collector and it lies directly on the ground, on the surface of the roof, etc.

In episode 2 of this film, primitive and factory collectors are compared on the topics of winter operation, ease of connection, economic feasibility, and areas of practical application.

Part two (about work in winter)

3, 4 series (maintenance)

– Experiment with pouring water into a sleeve of plastic film: