Do-it-yourself solar heating of a private house. Solar heating of a private house

The constant increase in tariffs and the dilapidated state of communications are forcing owners of private houses to actively look for alternative heating methods. One of the powerful and inexhaustible sources is the Sun, which supplies daily great amount kilowatt of free energy. Necessary install appropriate equipment, and dependence on network resource providers will be a thing of the past.

Always available, although it depends on weather conditions or time of day. For regions where climatic and weather conditions allow receive sufficient quantity kilowatt for heating, this option becomes optimal. Solar heating provides a lot of opportunities and advantages that should be discussed in more detail.

Design and principle of operation

An innovative technology that not everyone has a clear understanding of yet. Meanwhile, almost any homeowner has all the possibilities for installing and using the appropriate complexes. Necessity financial investments exists only for the purchase of equipment or equipment, he will receive everything else for free.

There are two options for organizing solar heating:

Solar collectors.

More cost method requiring presence a large amount of equipment. Photovoltaic elements are used, located in an open area at the desired angle for maximum perpendicular incidence of sunlight. They produce electricity, which accumulates in batteries , is converted into alternating current with standard parameters, after which it is sent to heating devices.

Heating from solar panels in a private house provides a lot of additional features. This method has a significant advantage - the electric current generated by solar panels can be used not only to heat the house, but also to power any appliances, for lighting or other needs.

Solar panels for home heating, the cost of which is quite high, may not be financially viable.

They operate on a different principle. They do not produce, but receive from the Sun thermal energy , which heats the coolant in containers or tubes. In principle, any container of water exposed to the sun can be considered a collector, but there are special designs that can demonstrate the greatest efficiency. This version of the system is much simpler, cheaper and available for self-production.

The resulting heat is immediately realized in increasing the temperature of the coolant, which is accumulated in a storage tank, from where it is distributed throughout the heating circuits of the house. In the best way heating is use of low-temperature systems such as heated floors. They do not require strong heating, which corresponds to the capabilities of solar collectors. At night, the coolant heated during the day is consumed.

For maximum efficiency of solar collectors, it is necessary to properly insulate the storage tank.

Advantages

The main advantage is that The sun is a constant and inexhaustible source, stable and completely predictable. Unlike wind turbines, which can sit idle for weeks, solar energy is supplied at predetermined time intervals. The only one the disadvantage is the possibility of cloudy or cold weather, when the efficiency of batteries and collectors decreases. However, modern designs make it possible to obtain a minimum amount even in the most difficult conditions, so no surprises threaten the heating system.

Moreover, we must not forget that Solar energy is completely free. If when heating the house with gas or electric boilers you have to purchase the equipment itself and then constantly pay for energy or fuel, then solar energy is not paid for, which significantly changes the level of profitability of the equipment and the entire system as a whole.

However, we should not forget that solar heating of a private house, the price and labor costs for installation of which often become the main problem, beneficial only in regions with suitable climatic and weather conditions.

An additional advantage is high maintainability of the system and the ability to increase its performance. There are no restrictions in this matter - how many panels or collectors are installed, so much energy will be received. If the installed kit turns out to be incapable of effectively heating the house, it can always be strengthened by adding the required amount of equipment. This is convenient if you need to rebuild or expand the house, make an extension, etc. Need to buy new system it does not arise completely.

Types of heating

Photovoltaic cells do not work exclusively for heating, which is a special case of their use, while solar collectors only serve as power sources for heating circuits. Therefore, we will consider exactly collectors, providing heating using solar panels, the price of which is significantly lower than that of photovoltaic cells.

There are several designs of solar collectors:

open;
tubular;
flat collectors.

These designs have different capabilities and are used to solve problems corresponding to their effectiveness. Let's take a closer look at them:

Open solar collectors

Open designs are the most simple and even primitive. They are containers, usually black narrow oblong plastic trays filled with water. They are not covered with anything, water is in the open air(hence the name).

Such designs have a lot of disadvantages:

the ability to give a positive effect only at positive temperatures;
a relatively small temperature difference between the collector and the external environment is required;
the durability of such installations is low - usually one season;
as a consequence of the above - extremely low.

It is impossible to use such installations to solve serious problems, so they are used for heating water in outdoor or mobile swimming pools, summer shower and so on. however, there are also advantages - such devices are very simple. A solar heater can easily be made independently, and in regions with suitable climatic conditions its capabilities are significantly expanded.

Tubular collector varieties

Tubular vacuum collectors are more serious devices capable of heating homes or other premises. They consist of the following elements:

body coated with black paint and shaped like a flat box;
distributor (or, as it is sometimes called, manifold) - a tube with several connecting pipes on the sides;
vacuum tubes made of glass.

The efficiency of the device is ensured by the presence of a vacuum, the thermal conductivity of which is practically absent and eliminates losses.

There are several types of tubular manifolds, differing in the design of the distributor and tubes:

Direct Heated Coaxial Tubes. The coolant is prepared in direct contact with the absorbing surface
Heat-pipe system. The tubes are connected to the distributor through special sockets and release the heated coolant through them. The design is convenient due to its high maintainability.
U-type system. The tubes are double length and bent in half. The beginning is connected to one distributor and the end to the other. This scheme allows you to increase the time of contact with solar heat, thereby increasing the heating efficiency.
Pen systems. They are a modification of the heat-pipe system, covered with a transparent plate with a vacuum under it. They provide increased efficiency, but have a high price and low maintainability.

Tubular collectors are usually installed on the roof of a house.

Flat closed systems

Solar heating of the house using flat systems allows you to get high efficiency at relatively low costs. The design is based on a special insulated metal plate with an absorbent coating, called an adsorber. A tube with coolant is soldered onto the plate in zigzags. The front side is covered with a transparent lid, from under which the air is pumped out. This type of solar heater able to work even at sub-zero temperatures. This allows you to heat your home with solar panels in winter; user reviews allow you to make fairly optimistic forecasts about the future of this heating method.

There are simpler types of flat-plate collectors where there is no vacuum. They are less efficient, but the cost and maintainability are much higher. Solar heating flat type non-vacuum design will cost much less, and the possibility of restoring panels increases their service life.

Selecting a solar collector and its installation

A homeowner who decides to create solar heating for a private home with his own hands faces a The task is to choose the most suitable type of collector. This issue is quite complex, but it is necessary to understand it.

Open collectors are not suitable due to their low capabilities, so there is no point in talking about them. Usually the choice is made between tubular and flat views . The first and most significant criterion The choice usually becomes the ratio of price and quality of products.

This approach is justified, but maintainability cannot be ignored. So, vacuum tubes cannot be changed in all types of manifolds, which makes the choice risky. If one of them fails, for some types of collectors the entire panel will have to be replaced, which will require expense. In general, all vacuum devices are a rather risky purchase, since any mechanical impact threatens the loss of a source of thermal energy.

By selecting best option, . For it you need to choose a suitable site located near the house. This is important because transporting coolant over long distances will require high-quality insulation and installation of a circulation pump. Typically, collectors are installed on the roof to allow circulation by gravity. The only problem is the location of the slopes relative to the position of the sun in the sky - sometimes you have to install a tracking system for turning panels. It's expensive and requires use flexible tubes, but the resulting effect is much higher.

Connection diagrams to the heating system

Do-it-yourself solar heating must be finally realized by connecting it to the heating system. The optimal way would be using heated floors, the coolant temperature for which does not exceed 55 degrees. Let's look at the connection diagrams that provide heating of the house with solar energy:

With water manifold

Water collectors directly connected to the heating circuit of the house. There are two options for joining: summer and winter.

Summer option, as a rule, it is used to supply heated water to the shower or for other needs, since heating the house in the summer is not needed. the simplest - the collector is installed in an open area, The water, heating up, rises to a storage tank installed at a higher level. As it is disassembled, the container becomes empty, so recharge is constantly supplied to it, entering the collector and receiving thermal energy in it. This method is simple and can be done with your own hands without any problems.

The winter version is more difficult. A collector installed in an open area supplies heated coolant(it is recommended to use antifreeze) into the heat exchanger coil. It is a vertically mounted container with a coil inside. Two loops arise - in one, antifreeze circulates (in a circle between the collector and heat exchanger), in the other, the coolant circulates (from the heat exchanger to the heating circuit and back). Antifreeze circulation must be ensured using a circulation pump, otherwise the system will not work. Coolant circulation can be organized either naturally or forcefully using a pump. The best option heating circuit- a heated floor system that allows you to get maximum effect both during the day and at night.

With solar battery

Solar heating with your own hands, created on the basis of solar panels, is carried out by installing an electric heater. In this case, photovoltaic elements only provide power to the heating elements installed in the electric boiler, without being directly related to the heating circuit.

The heating system and solar panels with the entire complex of equipment are mounted separately. The connection method is chosen arbitrarily, based on the characteristics of both systems. The boiler, pump and other devices are connected in the usual way, There are no specific requirements.

The operation of a solar heating system is carried out in accordance with the design of the collectors, their number and other features.
The main task for the owner it becomes maintaining cleanliness, timely removal of dust and other contaminants. This allows for maximum thermal energy intake and increases the efficiency of the entire system as a whole.
Necessary qualitatively insulate all connecting pipelines and storage tanks, excluding heat loss.
It is recommended to always keep one or two panels in reserve so that in case of mechanical damage you can quickly replace them. Following these simple recommendations will increase the efficiency of the system and ensure comfort and coziness in the home.

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In many developed countries of the world, solar collectors are used everywhere for heating homes. Such designs are replacing traditional heating systems not only in the south, but also in regions with temperate climate.

Of course, you can buy ready-made ones, such as those shown in the photo, but their price is still quite high. Organizing solar heating at home with your own hands is not difficult - it only requires time and basic knowledge of physics. Of course, not everyone can make a vacuum solar collector on their own. But there is more simple system. When installing a solar heating structure, you will have to not only install collectors on the roof of the house, but also internal elements.

Advantages of using solar systems

Installing solar collectors will significantly reduce the cost of traditional heating. Solar energy is free, and in addition, solar systems do not harm the environment. That is why in countries where authorities are concerned about the environment, this method of heating houses is widespread (read: ""). Massive use of solar systems will save resources that are traditionally used for heating (coal, natural gas) and solve the energy problem. Solar heating has the following advantages:

efficient operation and significant savings on the main heating system of the house;
safety of use;
long service life;
aesthetic appearance, the ability to select collector parameters.

Features of solar collectors

Solar heating systems for a private home are most effective in regions where there are a large number of sunny days. In addition, in winter the sunlight should also be quite intense. When installing such a heating system, the following features must be taken into account.

In order for the heating design to be effective, it is necessary to properly insulate the house. It is recommended to combine solar heating with other types - gas or electric - this is the best option. Integration of solar system elements into a traditional heating scheme significantly increases the heating efficiency of a home and reduces material costs.

In regions characterized by low level insolation (the flow of sun rays onto a horizontal surface), you need to correctly calculate the area of the collectors and strictly follow the installation instructions so that the system works as efficiently as possible. Experts recommend installing collectors at an angle equal to geographical latitude terrain, in which case they will be more effective. The fact is that the maximum level of absorption solar energy occurs if their surfaces are at right angles to the insolation.

When determining the degree of ray flux, it should be remembered that its intensity is much higher in the middle of the day. Therefore, it is advisable to place the surfaces in a southerly direction. Minor deviations in the south-east and south-west directions are acceptable. When installing collectors, it is necessary to ensure that they are not shaded by trees or neighboring buildings.

When organizing solar heating with your own hands, you need to slightly increase the angle of inclination to increase the efficiency of these devices in winter. At the same time, in the summer, the efficiency of the system will decrease slightly, but this is acceptable, since in any case there will be an excess of thermal energy.

Elements of a solar heating system

The set of solar system elements may change depending on the wishes of the customer and the characteristics of the plant’s production, but the principle of the set remains constant.

The solar heating system consists of:

vacuum manifold;
sediment that transfers coolant from the collector to the storage tank;
a controller that performs the function of controlling the operation of the system;
storage tank for hot water with a capacity of 500-1000 liters (read also: " ");
peak closer, represented by an electric heater, heat pump or other element.

Solar systems also allow you to install heated floors, and the costs associated with the purchase and installation of equipment will quickly pay off.

To create a collector you will need the following materials:

coil from an old or faulty refrigerator;
slats for assembling the frame;
foil, ordinary glass;
rubber mat;
a container for water and pipes for its supply and drainage.

Before you start doing solar heating country house, you need to make a collector. Before this, the coil is thoroughly washed, removing any remaining freon, and the frame, assembled from slats, is adjusted to fit. The coil must fit freely in the frame. The dimensions of the rubber mat should be similar to the dimensions of the frame. Read also: "".

When assembling the collector, you must strictly follow the instructions:

Foil, a frame of slats and a coil are laid on a rubber mat, in exactly this sequence. When assembling the frame, small holes are made in its walls; they should be sufficient so that the coil tubes can be removed through them.
The coil is secured using clamps from the same refrigerator. WITH reverse side they are secured with screws. Also, slats are nailed on the same side - this is necessary so that the structure acquires the required rigidity.
The gaps formed between the frame and the foil are sealed with tape. Thereby heat losses are minimized and solar heating becomes more efficient. The finished collector is covered with glass and taped around the entire perimeter. For additional sealing of the structure and greater reliability, the glass is secured with several screws. The solar collector is then attached to special supports.

How to make a solar collector yourself, video example:

How the system works

There are different types of collectors, and although the principle of operation of each of them is almost the same, there are still some differences between them. In this case, the operation of a homemade coil system will be considered.

Thus, the heating system consists of:

collector;
reservoir tank;
pipes for supplying hot water and draining it;
pipes for entering the cold water collector;
pressure relief valve;
shut-off valve;
make-up valve (read also: " ");
drain valve.

The heating system works automatically; home owners rarely have to intervene in this process. For the system to function effectively, in winter the collector must be cleared of adhering snow, as it will reflect the sun's rays and render the device useless.

Solar collectors are quite effective in regions with a temperate climate, and not just in the south. Even if there are many cloudy days in winter, enough ultraviolet radiation still comes through the clouds to at least partially heat the house. However, in this case, a solar heating system alone cannot be used - additional heat sources will have to be used. But in any case, the cost of heating the house will be significantly reduced.

With rising energy prices, the use of alternative energy sources is becoming increasingly important. And since heating is the main expense item for many, we are talking about heating first of all: you have to pay practically all year round and considerable amounts. When you want to save money, the first thing that comes to mind is solar heat: a powerful and completely free source of energy. And it’s quite possible to use it. Moreover, although the equipment is expensive, it is several times cheaper than heat pumps. Let's talk in more detail about how solar energy can be used to heat a house.

Solar heating: pros and cons

If we talk about using solar energy for heating, then you need to keep in mind that there are two different devices for converting solar energy:

Both options have their own characteristics. Although it must be said right away, whichever one you choose, do not rush to abandon the heating system that you have. The sun rises, of course, every morning, but your solar cells will not always get enough light. The smartest decision is to do combined system. When the sun's energy is sufficient, the second heat source will not work. With this you will protect yourself and you will live in comfortable conditions, and save money.

If there is no desire or opportunity to install two systems, your solar heating should have at least a double power reserve. Then we can say for sure that you will have warmth in any case.

Advantages of using solar energy for heating:

Flaws:

Dependence of the amount of incoming heat on the weather and region.
For guaranteed heating, you will need a system that can operate in parallel with a solar heating system. Many manufacturers heating equipment provide for this possibility. In particular, European manufacturers of wall-mounted gas boilers provide for joint operation with solar heating (for example, Baxi boilers). Even if you have installed equipment that does not have this capability, you can coordinate the operation of the heating system using the controller.
Solid financial investment at the start.
Periodic maintenance: tubes and panels must be cleaned of adhering debris and washed from dust.
Some of the liquid solar collectors cannot operate under very low temperatures Oh. On the eve of severe frosts, the liquid must be drained. But this does not apply to all models and not all liquids.

Now let's take a closer look at each type of solar heating element.

Solar collectors

Solar collectors are used for solar heating. These installations use the heat of the sun to heat the coolant fluid, which can then be used in a water heating system. The specificity is that a solar water heater for heating a house produces only a temperature of 45-60 o C, and shows the highest efficiency at 35 o C at the outlet. Therefore, such systems are recommended for use in conjunction with warm water floors. If you don’t want to give up radiators, either increase the number of sections (approximately twice as much) or heat up the coolant.

To provide a home warm water and for water heating you can use solar collectors (flat and tubular)

Now about the types of solar collectors. Structurally there are two modifications:

flat;
tubular.

In each of the groups there are variations in both materials and design, but they have the same operating principle: a coolant runs through the tubes, which is heated by the sun. But the designs are completely different.

Flat-plate solar collectors

These solar heating systems have simple design and therefore they can be made with your own hands if desired. A durable bottom is secured to a metal frame. A layer of thermal insulation is laid on top. The housing walls are also insulated to reduce losses. Then there is a layer of adsorber - a material that absorbs solar radiation well, turning it into heat. This layer is usually black in color. The adsorber is equipped with pipes through which the coolant flows. From above, this entire structure is closed with a transparent lid. The material for the cover can be strained glass or one of the plastics (most often it is polycarbonate). In some models, the light-transmitting material of the cover may undergo special treatment: to reduce reflectivity, it is made not smooth, but slightly matte.

The pipes in a flat-plate solar collector are usually laid in a snake pattern, and there are two holes - inlet and outlet. Single-pipe and two-pipe connections can be implemented. This is what you like. But for normal heat exchange a pump is needed. A gravity-flow system is also possible, but it will be very inefficient due to the low speed of the coolant. It is this type of solar collector that is used for heating, although it can be used to efficiently heat water for hot water supply.

There is a variant of a gravity collector, but it is used mainly for heating water. This design is also called a plastic solar collector. These are two plates of transparent plastic, hermetically sealed to the body. There is a labyrinth inside to move water. Sometimes the bottom panel is painted black. There are two holes - inlet and outlet. Water is supplied inside, warmed by the sun as it moves through the labyrinth, and comes out warm. This scheme works well with a water tank and easily heats water for domestic hot water. This is a modern replacement for a conventional barrel installed on an outdoor shower. Moreover, a more effective replacement.

How efficient are solar collectors? Among all domestic solar systems today they show top scores: their efficiency is 72-75%. But not everything is so good:

they do not work at night and do not work well in cloudy weather;
large heat losses, especially in windy conditions;
low maintainability: if something breaks down, then a significant part, or the entire panel, needs to be replaced.

However, heating a private house from the sun is often done using these solar installations. Such installations are popular in southern countries with active radiation and positive temperatures in winter period. They are not suitable for our winters, but in the summer season they show good results.

Air manifold

This setup can be used for air heating Houses. Structurally, it is very similar to the plastic collector described above, but air circulates and heats up in it. Such devices are hung on walls. They can operate in two ways: if the solar air heater is sealed, air is taken from the room, heated and returned to the same room.

There is another option. It combines heating with ventilation. There are holes in the outer housing of the air manifold. Through them, cold air enters the structure. Passing through the labyrinth, it is heated by the sun's rays, and then warmed up it enters the room.

Such heating of the house will be more or less effective if the installation occupies the entire southern wall, and there is no shadow on this wall.

Tubular manifolds

Here, too, coolant circulates through pipes, but each of these heat exchange pipes is inserted into glass flask. They are all connected in a manifold, which is essentially a comb.

Diagram of a tubular collector (click to enlarge the picture)

Tubular collectors have two types of tubes: coaxial and feather. Coaxial - a pipe in a pipe - nested one inside the other and their edges are sealed. A rarefied airless environment is created inside between the two walls. That is why such tubes are also called vacuum tubes. Feather tubes are just a regular tube sealed on one side. And they are called feather ones because, to increase heat transfer, an adsorber plate is inserted into them, which has curved edges and is somewhat reminiscent of a feather.

In addition, heat exchangers of different types can be inserted into different housings. The first are the Heat-pipe thermal channels. This is a whole system for converting sunlight into thermal energy. A heat-pipe is a small-diameter hollow copper tube sealed at one end. On the second there is a massive tip. A substance with a low boiling point is poured into the tube. When heated, the substance begins to boil, part of it turns into a gaseous state and rises up the tube. Along the way from the heated walls of the tube, it heats up more and more. Fall into top part, where he has been for some time. During this time, the gas transfers part of the heat to the massive tip, gradually cools, condenses and settles down, where the process is repeated again.

The second method is U-type, which is a traditional tube filled with coolant. There's no news or surprises here. Everything is as usual: the coolant enters on one side, passes through the tube, and is heated by sunlight. Despite its simplicity, this type of heat exchanger is more effective. But it is used less often. And all because solar water heaters of this type form a single whole. If one tube is damaged, the entire section must be replaced.

Tubular collectors with a Heat-pipe system are more expensive, show lower efficiency, but are used more often. And all because a damaged tube can be changed in a couple of minutes. Moreover, if a coaxial flask is used, then the tube can also be repaired. It is simply disassembled (the top plug is removed) and the damaged element (thermal channel or the bulb itself) is replaced with a working one. The tube is then inserted into place.

Which collector is better for heating?

For southern regions with mild winter and a large number of sunny days a year the best option- flat collector. In such a climate it shows the highest productivity.

Suitable for regions with harsher climates tubular manifolds. Moreover, systems with Heat-pipe are more suitable for harsh winters: they heat even at night and even in cloudy weather, collecting most spectrum of solar radiation. They are not afraid of low temperatures, but the exact temperature range needs to be clarified: it depends on the substance located in the thermal channel.

These systems, when properly calculated, can be basic, but more often they simply save heating costs from another, paid source of energy.

Another auxiliary heating could be an air manifold. It can be made to cover the entire wall, and it can be easily done with your own hands. It is perfect for heating a garage or cottage. Moreover, problems with insufficient heating may arise not in winter, as you expect, but in autumn. In frost and snow, the sun's energy is many times greater than in cloudy, rainy weather.

Solar panels

When we hear the words “solar energy,” we first think of batteries that convert light into electricity. And this is done by special photoelectric converters. They are produced by industry from various semiconductors. Most often for household use We use silicon photocells. They have the lowest price and show fairly decent performance: 20-25%.

Solar panels for a private home are common in some countries

You can directly use solar panels for heating only if you connect a boiler or other electric heating device to this current source. Also, solar panels in combination with electric batteries can be integrated into the home’s electricity supply system and thus reduce monthly bills for used electricity. In principle, it is quite possible to fully meet the family’s needs from these installations. It just takes a lot of money and space. On average, you can get 120-150W per square meter of panel. So count how many squares of roof or local area should be occupied by such panels.

Features of solar heating

The feasibility of installing a solar heating system raises doubts among many. The main argument is that it is expensive and will never pay for itself. We have to agree that it is expensive: the prices for equipment are quite high. But no one is stopping you from starting small. For example, to evaluate the effectiveness and practicality of the idea of making a similar installation yourself. The costs are minimal, and you will have a first-hand idea. Then you will decide whether to get involved with all this or not. Here's the thing: all the negative messages are from theorists. Not a single one was encountered from practitioners. There is an active search for ways to improve and alterations, but no one said that the idea is useless. This says something.

Now let's talk about the fact that installing a solar heating system will never pay off. While the term is paying off

There is a lot of bridges in our country. It is comparable to the service life of solar collectors or batteries. But if you look at the dynamics of price growth for all energy resources, you can assume that it will soon decrease to a completely acceptable time frame.

Now let's talk about how to make the system. First of all, you need to determine the needs of your home and family for heat and hot water. The general methodology for calculating a solar heating system is as follows:

Knowing in which region the house is located, you can find out how much sunlight falls on 1m2 of area in each month of the year. Experts call this insolation. From this data, you can then estimate how many solar panels you need. But first you need to determine how much heat is needed for hot water preparation and heating.
If you have a hot water meter, then you know the volume of hot water you use monthly. Display the average consumption data for the month or calculate based on the maximum consumption - whoever wants it. You should also have data on heat losses at home.
Take a look at the solar heaters you would like to install. Having data on their performance, you can roughly determine the number of elements needed to cover your needs.

In addition to determining the number of components of the solar system, you will need to determine the volume of the tank in which hot water for hot water will accumulate. This can be easily done if you know your family's actual expenses. If you have a DHW meter installed and you have data for several years, you can display the average consumption per day ( average consumption per month divided by the number of days). This is approximately the volume of tank you need. But the tank needs to be taken with a reserve of 20% or so. Just in case.

If there is no hot water supply or meter, you can use consumption standards. One person spends on average 100-150 liters of water per day. Knowing how many people permanently live in the house, you will calculate the required tank volume: the norm is multiplied by the number of residents.

It must be said right away that a solar heating system, which covers about 30% of the heat demand and fully supplies hot water, is rational (from the point of view of payback) for central Russia. This is an average result: in some months, heating will be 70-80% provided by the solar system, and in some months (December-January) only 10%. Again, a lot depends on the type of solar panels and the region of residence.

Moreover, it’s not just a matter of “to the north” or “to the south.” It's a matter of the number of sunny days. For example, in very cold Chukotka, solar heating will be very effective: the sun almost always shines there. In the much milder climate of England, with eternal fogs, its effectiveness is extremely low.
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Results

Despite many critics who talk about the inefficiency of solar energy and the payback period being too long, all more people at least partially switch to alternative sources. In addition to saving, many are attracted by independence from the state and its pricing policy. In order not to regret the wasted amounts of money invested, you can first conduct an experiment: make one of the solar installations with your own hands and decide for yourself how attractive it is to you (or not).

Is it possible to provide your home with solar thermal energy? Today we will discuss the prospect of using solar systems as the main source of heating, and consider the issue of economic feasibility and efficiency of solar collectors.

Main components of the heating system

The source of heating for the solar system is solar collectors, the purpose of which is to transfer the energy of the infrared spectrum of solar radiation to the coolant as efficiently as possible. The thermal range of sunlight is 40-45% of the total radiation flux, in specific figures it is 200-500 W/m2 depending on latitude, time of year and day.

In principle, to build the simplest solar system, only collectors are sufficient. Through their channels can circulate plain water, used for household needs and home heating. However, this approach is not effective enough for a number of reasons, the first of which is the lack of replenishment of energy losses for a full day. Therefore, one of the most important elements of a solar heating system is a heat accumulator - a container with water.

Scheme of heating a house with solar collectors: 1 - cold water supply; 2 - heat exchanger; 3 - heat accumulator; 4 - temperature sensor; 5 - coolant circuit; 6 - pumping station; 7 - controller; 8 — expansion tank; 9 - hot water; 10 - three-way valve; 11 - solar collector

Also a kind of limitation is technical device solar collector. Its channels have a rather small flow area, which creates a risk of clogging with mechanical impurities. There is also a high probability of the coolant freezing at night, while the upper limit of the operating temperature range is 200-300 °C. The collectors are designed for rapid continuous circulation of coolant, which enters at a low temperature and heats up quickly sunlight and just as quickly transfers heat to the battery.

Vacuum U-shaped solar collector tubes

For these reasons, it is customary to use propylene glycol with a set of special additives for direct heating in heat pipes. So, the third mandatory element of a solar heating system is a special coolant and exchange circuit, which is often structurally included in the heat accumulator, or can be part of the collector itself.

Types and differences of collectors

Without going into the technical details of the device, the main difference between flat and vacuum collectors lies in the advisability of their use in different climatic zones. Flat-plate collectors are best used in southern latitudes with prevailing temperatures above zero, vacuum collectors - closer to northern latitudes.

Design of a flat solar collector: 1 - coolant outlet; 2 — collector frame; 3 - structured hail-resistant glass; 4 - absorber; 5 - copper tubes; 6 - thermal insulation; 7 - coolant inlet

The feasibility of using certain types of solar collectors is due to a number of features:

the inability of vacuum collectors to independently clear snow;
high heat losses of flat-plate solar collectors, growing along with the temperature difference;
low resistance of flat collectors to wind loads;
high cost of the project on vacuum solar collectors;
low temperature range effective application flat collectors.

Design of a vacuum manifold with indirect heat transfer: 1 - cooled coolant inlet; 2 - heat exchanger (collector); 3 - sealed plug; 4 - vacuum tube; 5 — aluminum plate (absorber); 6 - heat pipe; 7 - working fluid; 8—output of heated coolant; 9 — heat sink body; 10 — heat pipe condenser; 11 - insulation

One of the most important differences lies in the installation process. Flat-plate collectors require delivery to the roof assembled, while vacuum collectors can be assembled on site. Also, flat-plate collectors usually do not have their own heat accumulator and exchange circuit.

Problems of solar energy

Solar heating systems are not without their drawbacks, the most important of which is the variability of the energy source. At night, the system does not heat up, and during prolonged cloudy weather, waiting for clear skies to heat the house is below average. If the battery is sufficiently large volume able to save required quantity warmth at least until the morning, then several days of autonomous operation in low light conditions can only be counted on with a significant expansion of the solar farm. This, in turn, causes the opposite problem: when reaching maximum power mode (for example, on a clear spring day), such a solar system will require more intense heat removal or temporary shutdown of several absorbers with their shading.

It is important to understand that solar systems in the realities of the Russian climate cannot be used as the only or main source of heating. However, they can significantly reduce energy consumption during the heating season. Hybrid collectors, in which heaters are combined with photocells, work especially effectively. If cloudiness blocks most of the IR radiation, then the loss of the photoelectric part of the spectrum is not so significant.

Another disadvantage of solar collectors is the need for forced circulation of coolant in the collector-accumulator system. Some vacuum manifolds are equipped with a tank designed for natural circulation and located above the absorber. Such installations are usually used in hot water supply systems with water intake under cold water pressure. But there are still ways to establish joint operation of such solar collectors with a heating system.

Integration into the heating system

There are two ways to combine solar collectors with an arbitrarily complex liquid heating system. The main source of energy can be either gas or electricity - there is no significant difference.

The first option is to heat the common daily battery. The storage device communicates with the boiler jointly and sequentially, if there is not enough high temperature the latter comes into operation and heats the liquid. A properly designed system of this kind can operate effectively even without forced circulation.

1 - heating circuit; 2 - heating liquid; 3 - temperature sensor; 4 - pumping station; 5 - controller; 6 - pump; 7 - expansion tank; 8 - sanitary water; 9 - cold water; 10 - DHW; 11 - solar collector; 12 - heating boiler

The second type of combination involves the use thermal battery with two circuits. Through one, heat is removed from the collector, through the second, the coolant in the system is heated, water from the battery serves as a source of hot water. Since the circuits are isolated from each other, more heat-intensive liquids or antifreeze can be used in the heating system and the heat exchange cycle from the solar collector. The main disadvantage is the energy dependence of the system, because circulation in both circuits is forced.

1 - cold water supply; 2 - temperature sensor; 3 - solar collector heat exchanger; 4 - boiler heat exchanger; 5 - collector coolant circuit; 6 - pumping station; 7 - controller; 8 — expansion tank; 9 - circulation pump; 10 - hot water outlet; 11 - heating boiler; 12 - solar collector

Power calculation and installation steps

The transition to solar energy does not accept haste and a superficial approach. Often, conclusions about the feasibility of installing a solar system can be made only after several years of observations and calculations.

Unfortunately, relying on insolation maps does not make much sense, because local weather conditions can greatly distort the average statistical indicators. Therefore, the first thing you need to do is to compile an intensity report yourself solar radiation at the installation site of the collectors. Pyranometers are used for measurements; within 5 thousand rubles you can purchase a budget device with a sufficient set of functions.

Measurements should be taken at different times of the day at intervals of about a week throughout the year. During the measurement process, it is necessary to take into account the angle of inclination and orientation of the collectors. The data obtained is ultimately verified with the statistics of the hydrometeorological center on the percentage of cloudy days per year.

To ensure high efficiency of the solar installation, the worst-case scenario should be considered, that is, the longest period with the lowest illumination should be taken as the starting point. Ideally, you can adjust for the likelihood of even more unfavorable weather conditions using meteorological statistics over the past 15-20 years. The obtained data on incoming solar energy will help to establish the required total area of the absorption field and determine the number of collectors that need to be purchased.

As mentioned, collectors are very rarely used as the main source of heating; they usually play a supporting role. But the share of participation can be calculated; it is indicated as a percentage of the total power of the house’s energy system or its heat loss. Having received the required number of kilowatts, it is multiplied by the optical efficiency of the absorbers, several coefficients are added - corrections for orientation, tilt, temperature regime, as well as a margin of safety.

Based on the “pure” value of the generated power, the following is selected:

the required number of collectors of a certain model and on average one backup solar collector for 10-15 in operation;
piping system recommended by the manufacturer throughput and heat resistance;
circulation group, shut-off valves, other auxiliary devices;
volume and location of the battery tank. In systems with a daily storage tank or a heat extraction power of more than 20 kW, it makes sense to build insulated concrete tanks with a volume of 15-20 m3.

For independent installation and maintenance, it is necessary to draw up a system design, allocate space for placing auxiliary devices and fix the solar collector on the southern (for the northern hemisphere) slope of the roof, taking into account the recommendations of the equipment supplier regarding wind loads. Don’t forget that by purchasing a full range of equipment from one distributor, you get the opportunity to draw up for free, if not a project for a solar heating system, then at least a list of well-compatible equipment and components.

Do you need a heat pump?

One of the main disadvantages of solar heating systems is the high cost. While the technology for producing flat-plate collectors is well established, vacuum absorbers remain expensive, and in certain weather conditions only they can be used successfully. But there is another alternative - air-type collectors.

Due to more simple device Their cost is less, plus there is the possibility of autonomous operation. The efficiency of air collectors is increased with the installation of a blower fan powered by an integrated solar panel. Due to the accelerated, but proportional to heating, cooling of the channels, return heat loss through the collector is minimized. Power limitation can be achieved by controlling the fan speed or simply shutting off the flow - air collectors are not afraid of thermal shock, and natural recirculation is easy to set up.

Flaw air systems to a small degree of heating of the coolant. The heat capacity of air is less, plus the absorber almost always heats up without focusing. To be able to integrate into heating system(which is most often necessary due to the impossibility of laying a ventilation duct into the heated room) a heat pump or split system is really needed.

But air heat pumps can also be used to increase the efficiency of air conditioning. With them, the circulation rate can be raised to values that are not acceptable in domestic ventilation systems, which gives a 2-3-fold increase in output due to the high temperature difference. At night, the collector will also have a small share of output at the operating temperature range.

The air used as a coolant can be dried or replaced with carbon dioxide or another more heat-intensive gas. However, it makes no sense to use heat pumps with a water primary circuit: they are initially designed to operate with a high temperature difference and therefore the increase in power is not enough to justify the cost of the installation.

Cost of solar heating installation

In general, you have to pay quite a lot for the pleasure of using clean energy, at least for today. To be fair, there is some positive news: over the past five years, the cost of producing flat-plate collectors has fallen by 2-2.5 times, and the same can soon be expected from devices with vacuum absorbers.

The cost of flat and vacuum collectors is determined by the volume of production - the value of solar radiation under ideal lighting conditions, that is, specific power. On average, for 1 kW of flat-type solar collectors you will have to pay about $350-500, and for a complete installation with an external battery - about $800-1000. The cost of vacuum solar collectors ranges in a higher range - from $600 to $1000-1200 per complex, depending on the quality of workmanship, tube material, heat exchanger insulation and other features.

For capacitive collectors, the standard measurement is in liters of water heated to the maximum possible temperature. The amount of electricity generated can be calculated either by the total area of the absorber, or by expressing it through specific heat capacity water. Depending on the complexity of the system, the cost varies greatly, the price of one example from the middle segment of the market reaches $1500 for 300 liters (for 4-5 residents) with a temperature difference of about 50 ° C, which is equivalent to 2.5 kW of power density.

The energy of the sun, which gives us light, electricity, heat, is rapidly conquering more and more new frontiers. No one can be surprised by various solar-powered instruments and devices, home helium power plants, various lamps, street garlands, traffic lights powered by solar energy.

And of course, the logical direction for using solar energy was to use it for heating, heating water not only in a single private house, but also in big houses, in public buildings.

Of course, solar systems are not able to provide round-the-clock operation for heating water. But they are able to replace traditional fossil energy sources - oil, gas, coal - during daylight hours. Since solar heating does not require the consumption of raw materials, there are no harmful emissions into the atmosphere and no environmental pollution.

Therefore, the use of solar energy for heating residential buildings and hot water supply will become increasingly important every year against the background of the expected increase in prices for oil, gas, and coal.

Solar heating system

In the simplest case, a solar heating system consists of one or more solar collectors connected in a closed loop to heating fittings - batteries or pipes laid in the floor. In this case, the radiators or floor pipes must be located above the collectors.

Then the water heated in the collectors, according to the laws of convection, will rise into the heating sections, and cold water will fall to the collectors. The radiators or pipes hidden in the floor heat up and thus heat the room without any additional devices.

The simplest solar heating scheme

But this is exactly the most simple circuit, explaining the principle of constructing the system. In reality, solar heating of a home involves installing a much more complex system. Before you buy solar water heaters or make them yourself, you need to determine what area needs to be heated and which home heating system is most suitable for these purposes.

It should be taken into account that none of the helium systems can provide round-the-clock operation. To heat rooms at night, you will have to use traditional heating means that run on one of the fossil fuels.

Typical scheme for solar heating and hot water supply

For small house with one or two rooms, an air heating system from solar collectors can be used. In such installations, air is used as a coolant, which, when heated in a collector system, enters the heated room through air ducts. Cooled air from this room enters the collector.

Solar air heating scheme

As for solar heating systems with liquid coolant, in principle they are all built the same way. The difference lies in the type of collectors used to heat the coolant.

The standard set consists of collectors, a storage tank with two heat exchangers (one is connected to the collectors, the second is connected to an additional heater). The storage tank must be equipped with good thermal insulation. The circulation of coolant and water in the heating system is supported by a pump group.

Heating system with flat collector

The design of a flat-plate collector is so simple that it can easily be made by hand. This device is a box containing an adsorber, pipes with coolant, and thermal insulation. Its manufacture does not require any special materials. All components are quite accessible. These are boards, fiberboard, wooden blocks, roofing iron, polystyrene foam, copper pipes, tempered glass, sealing materials, heat-resistant black paint.

So well put together homemade device capable of heating the coolant in stagnation mode to 150°C. As a rule, water is poured into the system with the addition of antifreeze in such a proportion that this solution does not freeze in the winter at night when the solar collector is not working.

Industrial flat collector

The collector or collector batteries are installed in such a way as to ensure maximum illumination by the sun. As a rule, this is the south side of the roof of the house. The coolant circulating in the circuit of the device is supplied by a pump to a heat exchanger located in the lower part of the storage tank. By continuously circulating in this system, the coolant heats the water in the boiler to 50°C - 60°C, which is quite enough to heat living quarters.

Flat solar collectors on the roof of a hotel and private house

To ensure a continuous supply of heat to residential premises at night, a backup water heating system is installed, powered by traditional energy sources - gas, electricity, coal, wood. The coolant circulating in the backup system enters the heat exchanger located above the main one.

This ensures heating of water in the boiler and a continuous heating cycle. If a backup heating system that runs on coal and wood can only be started manually, then a gas and electrical systems can turn on automatically, under the control of a special control unit.

Heating system with vacuum manifold

This system differs from the previous one only in the design of the collector. This device uses vacuum tubes to heat the coolant. Essentially, these vacuum tubes are a modified Dewar flask.

A double glass tube in which air is evacuated from the space between the walls. This ensures reliable thermal insulation of the inner tube. The inner tube contains an adsorber and a copper pipe, the upper end of which has several larger diameter than the pipe itself, and is sealed. The pipe is first filled with low-boiling liquid.

Under the influence of solar radiation, the tube heats up, the liquid in it begins to boil, and steam rises to the tip. There it gives up its heat, returns to a liquid state and flows down according to the laws of convection. This process continues continuously, heating the tip to 250°C -280°C. Fifteen to twenty such tubes are mounted into a single structure - a collector. The tips are inserted into the pipe through which the coolant circulates. The coolant is heated to 60°C - 80°C and supplied to the boiler heat exchanger.

Vacuum tube diagram

The vacuum manifold itself is installed obliquely to ensure free circulation of liquid in the copper tubes. With the exception of the collector, this heating system is no different from a system based on a flat-plate collector.

Vacuum collectors on the roof of a house

Heating system with parabolic mirror

Such a device is the most cumbersome and difficult to operate design. This is a long (several meters) mirror curved into a parabola. You can make such a mirror yourself by bending, for example, a sheet of plywood and pasting it with inside aluminum foil.

This parabolic-cylindrical mirror is mounted on a stable frame. At the focal point of the mirror, a long pipe is installed through which the coolant circulates. If the focus of the mirror is correctly determined and the pipe is installed at this focus, the temperature along the heating line of the pipe can reach 250°C - 300°C. But this is subject to correct installation and the orientation of the mirror to the sun.

Parabolic cylindrical mirror collector

The last condition is very important, since if the mirror is incorrectly oriented, heating power is lost and the temperature on the pipe drops significantly. To prevent this from happening, the installation with a parabolic cylindrical mirror must be equipped with a tracking device with an actuator.

The tracking device will track the position of the sun and orient the mirror accordingly in the vertical and horizontal planes. This significantly complicates and, consequently, increases the cost of the design.

If, in addition to solar collectors, a set of solar panels is installed to supply the house with electricity, then as a result you can get a completely autonomous power supply for the house, which does not depend in any way on shared networks energy supply.

Vacuum collectors and helium photovoltaic batteries

The sun will supply the house with electricity and heat, and at night, the electricity accumulated during daylight hours will heat the water in the backup heating system. The control unit will monitor timely switching on and off required devices, regulate the indoor temperature. And this is not the distant future. It's already working.