Solar heating of a private house: reviews, types, do-it-yourself, how to choose

In recent years, more and more attention has been paid to green energy and there are several reasons for this, including the struggle for the ecology of the world around us and the decline in global reserves of traditional fuels such as coal, oil and gas. In addition, having an installation powered by renewable energy sources (sun, wind, water and earth energy), you can create a completely independent system, the operation of which will not depend on energy supply organizations.

Solar heating of a private home is one of the types of use of solar energy, which, through conversion in special devices, is transferred to the coolant circulating in the heating system.

Device types

To convert solar energy into thermal energy, special technical devices called collectors are used. Depending on the design, they can be divided into two types:

Flat-plate collectors - this design is based on a flat box, closed on the outside with glass, in which tubes are placed through which the coolant circulates. Insulation is laid between the tubes, and an absorber is laid under the glass, a material that has the ability to accumulate thermal energy. The collector is connected to the external network through pipes mounted at the inlet and outlet of the pipes being laid.
Vacuum collectors - this group of devices is based on the use of vacuum tubes, which are mounted on a special frame and their upper part is placed in the coolant layer. The vacuum tube consists of two tubes, one of which is copper, placed in a larger glass one. A material with a high degree of absorption is placed in the interior of the glass tube. The air is evacuated from the glass tube, thereby creating a vacuum, which improves the characteristics of the device in terms of heat accumulation and transfer.

There is another type of solar collectors, these are flat air devices. In this design, air is used as a coolant, but due to the low efficiency of such models and inefficiency, such collectors are practically not used for heating houses.

Final Conclusion

It is very difficult to make full heating of a private house using solar panels. The only more or less realistic scenario is the use of split systems, or better yet, a geothermal heat pump, which has little dependence on the street temperature. The installation consumes little electricity, so it can operate from a home solar power plant.

We specifically excluded financial issues from the article, since we were talking about technical issues. But you need to understand that solar energy equipment - batteries, inverters and control units - cost a lot of money. To successfully solve a problem, you need to be a well-earning enthusiast.

A circuit with vacuum collectors connected to an indirect water heater will be cheaper. But this option has its own difficulties, for example, heat accumulation and collector stagnation in hot weather. There are no easy solutions to the difficult task of harnessing solar energy.

How to choose the best

In order to make the right choice and not make a mistake with the choice of the type of solar collector and its brand, you need to follow the selection criteria, which for such devices are:

Possibility of using a solar system in the region where the equipment is to be installed;
The power and performance of the device must correspond to the required values and usage indicators;
The amount of heat loss - determines the efficiency of a particular model and the required number of collectors capable of providing the heated object with thermal energy;
Possibility of installation in one or another location of the intended installation (geometric dimensions and weight);
Quality of workmanship and reliability of assembly (manufacturer's brand);
Service life and warranty period;
Device cost.

By following the above criteria and studying reviews on a specific model and company that produces similar products, you can choose the best option from those offered on the relevant market.

Method for increasing productivity

Usually, after experimenting with a small number of solar modules, private home owners go further and improve the system in various ways.

The easiest way is to increase the number of modules involved, accordingly, attract additional space to accommodate them and purchase more powerful related equipment

What to do if there is a shortage of free space? Here are some recommendations for increasing the efficiency of a solar station (with photocells or collectors):

Changing the orientation of modules. Moving elements relative to the position of the sun. Simply put, installing the bulk of the panels on the south side. During long daylight hours, it is also optimal to use surfaces facing east and west.

Tilt angle adjustment. The manufacturer usually indicates which angle is most preferable (for example, 45º), but sometimes during installation it is necessary to make adjustments taking into account geographic latitude.

Correct choice of installation location. The roof is suitable because it is most often the highest plane and is not obscured by other objects (for example, garden trees). But there are even more suitable areas - rotating sun tracking devices.

When the elements are positioned perpendicular to the rays of the sun, the system works more efficiently, but on a stable surface (for example, a roof) this is only possible for a short period of time. To increase this, practical tracking devices have been invented.

Tracking mechanisms are dynamic platforms that rotate with their planes following the sun. Thanks to them, generator productivity increases by about 35-40% in summer, and by 10-12% in winter.

The big disadvantage of tracking devices is their high cost. In some cases, it does not pay off, so there is no point in investing in useless mechanisms.

It is estimated that 8 panels is the minimum number at which the costs will be justified over time. You can use 3-4 modules, but under one condition: if they are directly connected to the water pump, bypassing the batteries.

Just the other day, Tesla Motors announced the creation of a new type of roof - with integrated solar panels. Elon Musk said that the modified roof will be cheaper than a conventional roof with collectors or modules installed on it.

What to pay attention to

When choosing a solar collector, in addition to the criteria given above, you need to pay attention to a number of points, taking into account which you can avoid inconvenience during further operation of the device.

It should be remembered that:

Flat-type models are more durable, but not easy to use. To repair them, it is necessary to stop the entire heating system, and in the absence of shut-off valves at the inlet and outlet of the collector, the entire amount of coolant must be drained.
Models using vacuum tubes are more repairable, but less durable. If it is necessary to replace tubes (one or more), they are replaced without stopping the heating system.
Flat-plate collectors are able to heat the coolant more than vacuum devices, which makes them more efficient when used in winter.
Air collectors are reliable and durable, but due to their technical characteristics, they are not capable of fully heating large construction volumes.
The collector's passport indicates its rated power, i.e. the ability to convert solar energy into thermal energy at the moment of maximum solar activity (noon) and in clear weather.
The correct location of the device in space, in relation to the surface of the earth, will avoid difficulties during operation.
Before deciding to purchase a specific model, it is necessary to develop a solar installation diagram, calculate its power and possible heat losses.

Efficient use of solar energy

The most obvious advantage of using solar energy is its universal availability. In fact, even in the gloomiest and cloudiest weather, solar energy can be collected and used.

The second advantage is zero emissions. In fact, it is the most environmentally friendly and natural form of energy. Solar panels and collectors do not produce noise. In most cases, they are installed on the roofs of buildings, without occupying the usable area of a suburban area.

The efficiency of solar heating in our latitudes is quite low, which is explained by the insufficient number of sunny days for regular operation of the system (+)

The disadvantages associated with using solar energy are the variability of illumination. At night there is nothing to collect, the situation is aggravated by the fact that the peak of the heating season occurs during the shortest daylight hours of the year. It is necessary to monitor the optical cleanliness of the panels; slight contamination sharply reduces the efficiency.

In addition, it cannot be said that operating a solar energy system is completely free; there are constant costs for equipment depreciation, operation of the circulation pump and control electronics.

A significant disadvantage of heating based on the use of solar collectors is the lack of ability to accumulate thermal energy. Only the expansion tank (+) is included in the circuit

Open solar collectors

An open solar collector is a system of tubes, unprotected from external influences, through which coolant heated directly by the sun circulates.

Water, gas, air, and antifreeze are used as coolants. The tubes are either fixed to the supporting panel in the form of a coil, or connected in parallel rows to the outlet pipe.

Open solar collectors are not able to cope with the heating of a private home. Due to the lack of insulation, the coolant cools quickly. They are used in the summer mainly to heat water in showers or swimming pools.

Open collectors usually do not have any insulation. The design is very simple, therefore it has a low cost and is often made independently.

Due to the lack of insulation, they practically do not store the energy received from the sun and are characterized by low efficiency. They are used mainly in the summer to heat water in swimming pools or summer showers.

Installed in sunny and warm regions, with small differences in temperature of the ambient air and heated water. They work well only in sunny, windless weather.

The simplest solar collector with a heat sink made from a coil of polymer pipes will provide the supply of heated water to the dacha for irrigation and domestic needs

Tubular collector varieties

Tubular solar collectors are assembled from individual tubes through which water, gas or steam flows. This is one of the types of open solar systems. However, the coolant is already much better protected from external negativity. Especially in vacuum installations, designed on the principle of thermoses.

Each tube is connected to the system separately, parallel to each other. If one tube fails, it is easy to replace it with a new one. The entire structure can be assembled directly on the roof of the building, which greatly simplifies installation.

The tubular collector has a modular structure. The main element is a vacuum tube; the number of tubes varies from 18 to 30, which allows you to accurately select the power of the system

A significant advantage of tubular solar collectors is the cylindrical shape of the main elements, thanks to which solar radiation is captured all day long without the use of expensive systems for tracking the movement of the luminary.

A special multilayer coating creates a kind of optical trap for sunlight. The diagram partially shows the outer wall of the vacuum flask reflecting rays onto the walls of the inner flask (+)

Based on the design of the tubes, feather and coaxial solar collectors are distinguished.

The coaxial tube is a Diaur vessel or a familiar thermos. Made from two flasks between which air is evacuated. A highly selective coating is applied to the inner surface of the inner bulb, effectively absorbing solar energy.

With a cylindrical tube, the sun's rays always fall perpendicular to the surface

Thermal energy from the internal selective layer is transferred to a heat pipe or internal heat exchanger made of aluminum plates. At this stage, unwanted heat loss occurs.

The feather tube is a glass cylinder with a feather absorber inserted inside.

The system gets its name from the feather absorber, which tightly wraps around a thermal channel made of heat-conducting metal.

For good thermal insulation, the air has been evacuated from the tube. Heat transfer from the absorber occurs without loss, so the efficiency of feather tubes is higher.

According to the method of heat transfer, there are two systems: direct-flow and with a heat pipe. Thermal tube is a sealed container with an easily evaporating liquid.

Since the easily evaporating liquid naturally flows to the bottom of the heat tube, the minimum inclination angle is 20° C

Inside the heat tube there is an easily evaporating liquid that receives heat from the inner wall of the flask or from the feather absorber. Under the influence of temperature, the liquid boils and rises in the form of steam. After the heat is transferred to the heating or hot water supply coolant, the steam condenses into liquid and flows down.

Water is often used as an easily evaporating liquid at low pressure. A once-through system uses a U-shaped tube through which water or heating fluid circulates.

One half of the U-shaped tube is intended for cold coolant, the second removes the heated one. When heated, the coolant expands and enters the storage tank, providing natural circulation. As with heat tube systems, the minimum angle of inclination must be at least 20⁰.

With a direct-flow connection, the pressure in the system cannot be high, since there is a technical vacuum inside the flask

Direct-flow systems are more efficient because they immediately heat the coolant. If solar collector systems are planned to be used all year round, then special antifreeze is pumped into them.

The use of tubular solar collectors has a number of advantages and disadvantages. The design of a tubular solar collector consists of identical elements that are relatively easy to replace.

Advantages:

low heat loss;
ability to work at temperatures down to -30⁰С;
efficient performance throughout daylight hours;
good performance in areas with temperate and cold climates;
low windage, justified by the ability of tubular systems to pass air masses through themselves;
possibility of producing high temperature coolant.

Structurally, the tubular structure has a limited aperture surface.

It has the following disadvantages:

not capable of self-cleaning from snow, ice, frost;
high price.

Despite the initial high cost, tubular collectors pay for themselves faster. They have a long service life.

Tubular collectors are open-type solar systems and are therefore not suitable for year-round use in heating systems (+)

Flat closed systems

A flat-plate collector consists of an aluminum frame, a special absorbent layer - an absorber, a transparent coating, a pipeline and insulation.

Blackened sheet copper is used as an absorber, which has ideal thermal conductivity for creating solar systems. When solar energy is absorbed by an absorber, the solar energy it receives is transferred to a coolant circulating through a tube system adjacent to the absorber.

On the outside, the closed panel is protected by a transparent coating. It is made of shockproof tempered glass with a transmission band of 0.4-1.8 microns. This range accounts for the maximum solar radiation. Shockproof glass provides good protection against hail. On the back side the entire panel is reliably insulated.

Flat-plate solar collectors are characterized by maximum performance and simple design. Their efficiency is increased due to the use of an absorber. They are able to capture diffuse and direct solar radiation

The list of advantages of closed flat panels includes:

simplicity of design;
good performance in regions with warm climates;
the ability to install at any angle with devices for changing the angle of inclination;
the ability to self-clean from snow and frost;
low price.

Flat-plate solar collectors are especially advantageous if their use is planned at the design stage. The service life of quality products is 50 years.

The disadvantages include:

high heat loss;
heavy weight;
high windage when the panels are positioned at an angle to the horizontal;
performance limitations when temperature changes exceed 40°C.

The scope of application of closed collectors is much wider than that of open-type solar systems. In summer they are able to fully satisfy the need for hot water. On cool days, when utilities do not include them in the heating period, they can work instead of gas and electric heaters.

For those wishing to make a solar collector with their own hands for a heating device in their dacha, we suggest that you familiarize yourself with practice-tested diagrams and step-by-step assembly instructions.

Advantages and disadvantages

Like any technical device, solar collectors have their own advantages and disadvantages, which determine the ability to use such products in certain operating conditions.

The advantages of use include:

Environmental safety for both the environment and humans.
Renewability and inexhaustible resource of energy used.
Possibility of creating a completely autonomous heating and hot water supply system from external energy sources.
Long service life.
Possibility of upgrading the autonomous system and its integration, if necessary, into a centralized heating system (from external energy supply sources).
Optimization of the heating system of a single facility in accordance with specified parameters.

Disadvantages of use can be considered:

The high cost of equipment and installation work determine the need for significant financial costs at the initial stage of use.
The efficiency of work depends on weather conditions, the region and landscape of location, the design of the building elements on which the collectors are installed (the shape of the roof, walls or free-standing elements).

Application and reliability of solar panels

The system of generating electricity from solar energy has been used all over the world for 30-40 years, if not more. During this time, panels and photocells have been seriously improved, the equipment has been tested in different climatic conditions on all 5 continents.

Considering the fashion in the 21st century for everything natural and environmentally friendly, there is every reason to believe that in the next 15-30 years the majority of the population around the world will switch to heating using solar panels and photovoltaic systems, thanks to which there will no longer be a need to build expensive large power plants and substations, as well as spending money on expensive and unfriendly fuel from oil and gas. Over time, as the cost of solar cells decreases and technology improves, more opportunities for the use of these devices will open up.

Solar energy, in fact, is already actively used by humanity (and not only in advertised electric cars). The simplest systems that already use photocells include:

Photoelectric pumping units, which have become an excellent alternative to hand pumps and diesel generators;
Battery systems that allow the battery to charge and store energy to be released when needed at any time;
Systems with a generator will provide electricity in cases where more is needed than a photovoltaic battery can provide. This combined use of a generator and photocells will significantly reduce the initial cost of the system;
Photovoltaic systems integrated into the electrical grid. Thus, part of the electricity can be taken from photocells, and if there is a shortage, from the general public power grid, while the battery is not used or is simply charged;
Industrial photovoltaic systems that operate completely silently, do not require fossil fuels and do not pollute the environment.

Average prices

At the moment, a fairly large number of companies from different countries of the world are represented on the market of solar systems used for heating and hot water supply. The cost of the models depends on the type of collector, its technical characteristics and the company that produces it. Average prices for the most popular models are:

Products (Germany):
Model “auroTHERM exclusiv VTK 570-1140” is a vacuum manifold, with an area of 1.0 m2 - cost from 73,000.00 rubles, and with an area of 2.0 m2 - from 145,000.00 rubles.
Solar collectors (Italy):

Model “KAIROS CF 2.0 ARISTON”, flat collector, area 2.0 m2. Cost – from 37,000.00 rubles.
Model “KAIROS VT 15B ARISTON” is a vacuum model, costing from 86,000.00 rubles.

Products (China):

Model “FPC-1200d” is flat type, with an area of 2.01 m2. Cost from 25,000.00 rubles.
Model “ES 20R-5” is a vacuum type, costing from 36,000.00 rubles.

Products (Russia):

Model, article 2900152 – flat solar collector, area 2.0 m2. The cost is from 21,000.00 rubles.
Model “VU-10” is a vacuum type, costing from 23,000.00 rubles.

Flat closed solar collectors

A flat-plate collector consists of an aluminum frame, a special absorbent layer - an absorber, a transparent coating, a pipeline and insulation.

The list of advantages of closed flat panels includes:

simplicity of design;
good performance in regions with warm climates;
the ability to install at any angle with devices for changing the angle of inclination;
the ability to self-clean from snow and frost;
low price.

Flat-plate solar collectors are especially advantageous if their use is planned at the design stage. The service life of quality products is 50 years.

The disadvantages include:

high heat loss;
heavy weight;
high windage when the panels are positioned at an angle to the horizontal;
performance limitations when temperature changes exceed 40°C.

Where can I buy

A solar collector is a product that can only be purchased from specialized organizations and companies that either produce similar devices or are focused specifically on selling equipment that runs on alternative energy sources.

The most correct way to purchase is to find a dealer of the manufacturer of a specific device model, and then conclude an appropriate purchase and sale agreement with him. If there are no dealers of companies producing solar collectors in the region where the potential buyer lives, then you can find an organization that specializes in this group of products. These two purchase options are the most optimal, because... specialists from such companies can provide assistance in choosing a model and suggest how to perform installation.

If the above listed acquisition methods cannot be carried out, then you can turn to the Internet, where a fairly large number of companies operating specifically in this area of energy are represented. The advantage of this purchasing method will be the lower cost of the products, but the negative point is that there will be no advice or tips on choosing a model and its installation; you will have to decide everything yourself.

Features of choice.

When choosing solar panels for heating your home, you need to consider several nuances:

Power is one of the main parameters affecting the cost of solar panels. Therefore, before purchasing them, it is necessary to determine the estimated electricity consumption. The accompanying documentation always indicates the maximum power generated by the batteries per hour in watts. But it must be taken into account that in cloudy weather it will be slightly smaller. The power also depends on the type of solar panels.

Size – significantly depends on the power of the panels and the type of their photocells. The roof must have the required dimensions to install the required number of panels.

On average 1 sq. A meter of solar panels produces about 120 watts in 1 hour.

Panels with a total area of 20 square meters. meters will provide a one-story country house with electricity in full.

Type - poly- and monocrystalline solar cells have a significantly higher cost than thin-sheet silicon ones. But they generate more electricity and require less roof surface.

Possibility to increase power if necessary. It can be easily expanded by adding additional solar panels. Replacing batteries by purchasing new, more efficient ones is not economically profitable. Therefore, it is necessary to take into account a small margin of roof surface.

Solar panels from leading manufacturers are guaranteed to last more than 25 years. Their reliability depends on the manufacturer. It is advisable to give preference to a well-known manufacturer. It provides free replacement of panels under warranty, provides assistance with installation, adjustment, repair, and capacity expansion.

Are the costs justified?

The cost of the equipment included in the solar installation kit is quite high, so always, before deciding to purchase such products, you need to calculate the cost of the required kit and the financial return that can be obtained from using such installations.

The set of equipment that will provide autonomous heating of the house, in addition to the collector, includes a number of technical devices, which is also reflected in the amount of costs for the entire set of equipment.

So, to create a heating system based on a solar collector you will need:

Collector.
Heat accumulator tank.
Expansion tank.
Circulation pump.
Pipes and valves.

Of all the equipment listed, the most expensive unit is the collector itself, therefore, in order to determine whether the costs of installing such a system are justified, you need to decide what is the prerogative in this matter, because the cost of boilers operating on gas or solid fuel , comparable to the cost of a solar collector.

In this regard, the decision on the advisability of installing this particular type of heating, and accordingly the cost of equipment, is determined by the criteria for selecting such systems, as well as the pros and cons of their operation, which were described above.

Heating a house with collector-type solar panels

At their core, collectors are really similar to solar panels, since they capture direct sunlight. An exception for the latter are thin-film plates that produce current from scattered light. As for collectors, flat models need hot solar radiation to heat water. The only option that actively supplies hot water to the pipes of the heating system all winter, even in dense clouds, is vacuum collectors

. It is the vacuum that saves precious heat.

If you decide to take the vacuum option, in this case you also have a choice - a direct or indirect water heating model. The former are considered seasonal, since the storage tank is located directly in the collector body, and tubes with a double shell, inside of which there is a vacuum environment, are directly connected to the tank. In winter, such models cannot be used, the water in them freezes.

Another thing is heating a house with solar panels of an all-season collector type. They will work even at -50 degrees and cloudy cover, since the storage tank is installed in the house. This system operates thanks to a coolant fluid moving through pipes between the spirals located inside the tank and the collector. The same liquid is poured into the cores of the vacuum tubes. The water is only in the storage tank; from it it flows through pipes into the batteries.

Is it true that solar heating is 20 times cheaper than typical gas heating?

How many times solar heating is cheaper than gas heating can be calculated by each user individually, because everything depends on many factors, such as the presence of low and high pressure gas lines, the type of gas, if any, and of course the factors that determine the possibility use of solar power plants.

An undoubted advantage, in comparison with gas boilers, will be the fact that when using solar collectors, after the initial costs of purchasing and installing equipment, thermal energy is subsequently generated free of charge, in the required volumes.

In addition, the use of solar energy is an environmentally friendly and safe production, eliminating many of the negative consequences that can occur when using gas equipment.

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. 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.

How to make your own air solar heating

Anyone can make their own heating system based on a solar collector, as long as they have the desire, the ability to work with hand tools and free time.

Since the main element, as already written earlier, in such a heating system is the solar collector, therefore its manufacture will be discussed.

The easiest way to make a flat type model is to do this you will need:

Material for making the frame (lumber, metal profile or dense plastic).
Copper tube.
Insulation – mineral wool or other (polystyrene or analogues).
Absorber – metal foil.
Durable glass that serves as an element that protects the insulation from precipitation and other negative influences.

The design of a flat-plate solar collector is as follows:

The frame of the collector and its body are made from lumber (board, plywood, etc.) or a metal profile (aluminum, ferrous metal). Insulation (thermal insulation) is laid on the lower surface, onto which a copper tube is mounted. It is necessary to provide fittings or a threaded connection at the ends of the tube to connect the collector to the heating system. Insulation is also laid on the sides. The joints of the housing elements are sealed to prevent heat loss. An absorber is placed on top of the tubes, covered with a layer of transparent thermal insulation and glass (collector cover). Pipes with coolant are supplied to the fittings, the device is ready for operation.

Options for self-assembly of the heating system

Today, there are several ways to assemble a solar heater with your own hands. Let's look at the most popular assembly methods. First option. Here you need a galvanized container for water. It should have a volume of approximately 100-200 liters. The technology for creating a solar battery has the following algorithm:

We place the container on the roof. It should be installed on the south side of the roof;
the roof surface must be covered with a metal sheet with a shiny surface;
put pipes on top of it;
we connect them to a barrel and a container for heated water.

Homemade solar collector option

With the help of such a battery, 100 liters of water can be heated by 60 degrees. This installation has high efficiency. But in winter, such a unit will not be effective. Second assembly option. To create this type of collector you will need:

steel boxes;
several flat steel radiators;
glass;
metal-plastic elements - fittings and pipes.

The system builds in this case proceed as follows:

steel boxes are mounted on the roof;
radiators are placed there;
Cover them with glass on top. This will reduce the water heating time;
the tubes must be laid with a downward slope;
be sure to ensure that the top of the device is located below the storage tank;
A plastic barrel with water is installed in the attic. Suitable volume - 160 l;
it must be connected to the radiator and water supply using metal-plastic devices - fittings and tubes. The water tube itself needs to be connected slightly above the middle of the tank;
Drain valves are installed at the bottom of the radiator. With their help, water is drained during the cold season.

Option with plastic barrel

Third option. It is used to heat a fairly large room. Has an efficiency of 45-55%. To create this type of heating system you will need the following materials:

any thermal insulation material;
wooden frame with a plywood bottom;
black metal mesh;
deflector;
transparent polycarbonate sheet;
several fans

The structure is assembled as follows:

drill round holes in the ramp. They are cut through for air intake;
to remove hot air we make rectangular holes at the top of the frame;
We put thermal insulation material on its bottom. A metal black mesh will act as a heat accumulator;
fans built into round holes;
then we install the support strips for the deflector. After this, we install the deflector itself. It will shape the air flow;
We install a transparent sheet on top.

Finished design

With the help of such a unit, you can effectively heat your home, as well as heat water.

Features of solar heating

The sun is an inexhaustible source of energy, but not in all regions it shines equally, in some places the number of sunny days is less than when there is bad weather outside, in others the strength of the sun’s rays is not great (northern regions). In this regard, I would like to note that, having the opportunity to use traditional heating methods, you should not abandon them completely; it is better to consider options for the combined use of both systems.

When installing a completely autonomous system based on the use of solar collectors, it is necessary to provide a significant power reserve, which will help to avoid problems with heating the house.

Real heating methods

As you understand from the above, it is quite difficult (and expensive) to implement full-fledged electric heating of a house with solar panels. Not every owner will decide to buy and install panels on an area of 100–150 m² in order to warm up a small house or cottage. This means that the circuit of electric boiler + water system + heating radiators is eliminated.

But the idea of heating with solar modules still cannot be called a utopia. We list the options implemented by homeowners in practice:

panels plus inverter air conditioners with a COP efficiency of 3.5–4;
connecting batteries directly to electric heaters without an inverter;
construction of a full-fledged solar power plant, sale of electricity to the state, the proceeds go to pay for traditional heating.

Addition. There is no point in discussing the use of panels as additional energy sources for main heating - this is an obvious solution.

Let's start with the third option, which is of interest to entrepreneurs. In countries where the state has established a so-called feed-in tariff, the homeowner can receive electricity from renewable sources and feed it into the general energy grid, making a profit. That is, the homeowner purchases the same 200–300 solar panels, but sells the energy at a good price, rather than wasting it in vain.

A large number of batteries will not fit on the roof of a residential building; a high-power station will have to be placed on the site

For example, in Ukraine the green tariff is 3 times higher than the usual one (as of June 2021). One condition must be met: the minimum productivity of the solar power plant is 30 kW. Build a power plant, supply energy to the network, and buy it yourself at three times the price.

Let's look at the remaining 2 options in more detail.

Heating by air conditioners

The method is based on the efficiency of inverter split systems, which deliver four times more heat inside the house than the electricity consumed. How to implement such heating:

First of all, we reduce the heat loss of the building as much as possible - we insulate the walls, floors and roof, and install energy-saving windows. The ideal heat consumption for a home of 100 m² is 6 kW.
We purchase 2 air conditioners with inverter compressors that operate at subzero outside temperatures. The total productivity of the units should be equal to the heat loss of the house, in our case - 6 kW. The consumption of such “splits” will not exceed 2 kW.
We are installing a solar station capable of providing electricity to air conditioners around the clock.
For heating on the coldest days, it is worth installing any traditional heat source - a boiler, a wood stove.

Mitsubishi Zubadan heat pumps consume even less energy than air conditioners, and generate four times more heat (COP = 4).
The video at the end of this section confirms that the described scheme is quite workable. One significant disadvantage: at negative temperatures, the efficiency of air conditioners decreases sharply; you cannot do without the help of a boiler. In temperate and northern climates, solar modules cannot cope alone.

Note. Most inverter split systems can operate in temperatures down to -15 °C. The COP efficiency factor is reduced to 1.5–2 (twice as much heat is generated as electricity consumed).

Using local heaters

We are talking about a significant reduction in the cost of the system in the case of using unpretentious consumers - conventional fan heaters. Due to the lack of an inverter, you will have to connect 12-volt heaters to the solar modules (you can take a car heater or do it yourself).

How to assemble a solar power generator:

We install the required number of batteries with an operating voltage of 12 volts.
We connect them with 2.5 mm² wires according to the diagram below - without an inverter.
We connect the load - a low-power 12 V fan heater.

In the video below, a specialist describes in detail all the nuances of such a connection. The method is suitable for heating individual rooms with 1–1.5 kW fan heaters. Heating the entire house is more difficult - you need to assemble several separate circuits with solar panels so as not to increase the cross-section of the wires.

Methods for connecting to the heating system

There are only two ways to connect solar installations to the heating system, which depend on the quality of such a system; it is the main source of thermal energy or a spare one that complements the traditional heating system.

Depending on this, the connection is made as follows:

Autonomous heating system.

In this heating system, cold water, which is the coolant, is recharged from external water supply sources. The thermal energy storage device is a storage tank, from which heated water is supplied to the heating and hot water supply systems of consumers.

Combined heating system.

In a combined heating system, the collector serves as an additional source of thermal energy, while the main source is a heating boiler operating on a certain type of fuel. In certain schemes, depending on the availability of external distribution networks, the boiler may be absent; in this case, the coolant from external heating networks flows directly into the buffer storage tank.

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. Solar heating on clear days provides water heating up to 70 degrees. Water circulation in the systems occurs naturally. Water heated in the collector, due to a decrease in density, moves upward into a special tank. Cold water, which has a higher density, moves to the bottom of the solar panel. After this, the process is repeated. A schematic representation of such a system can be seen in the photo.

Reviews

Thanks to the Internet, you can always find user reviews about various types of heating and the equipment used in its construction. Here are some of them:

Alexander (Stavropol Territory):

“Two years ago I read an article about how you can save on heating costs by installing a solar collector. I found a company specializing in the sale of such products and entered into an agreement with them for the supply and installation of 3 collectors of the SCH-30 model. They installed and installed it quickly and I’ve been using it for the second season now. Of course, it took a lot of money, but the effect of use exceeded my expectations. I completely abandoned central heating and hot water supply, fortunately we have a lot of sun. Accordingly, utility bills have decreased, but the most important thing is that now I do not depend on heating networks and water utilities, since I previously dug my own well. I’m very pleased with the rational investment of my funds.”

Konstantin (Lipetsk region):

“Many people argue whether the cost of purchasing equipment will pay off when installing an autonomous heating system based on solar collectors. There is no definite answer, but those who already use such devices say with confidence that this is beneficial, because skeptics do not take into account the fact that when connecting to external gas, heat and electricity networks, the organizations operating them ask for considerable sums when issuing technical specifications, as well as for the very fact of tapping into their communications. If we take into account that solar energy is an environmentally friendly sector of the economy, and the sun is an inexhaustible source of energy, then we can confidently say that green energy in general, and solar heating systems for housing, is the future.”

Tubular manifolds

Here, too, the coolant circulates through pipes, but each of these heat exchange pipes is inserted into a 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. It ends up in the upper part, where it stays 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.

Scheme of operation of the Heat-pipe thermal channel

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.

Regular U-tube is the most efficient heat channel

As a result, prospects for the development of solar technologies

If on Earth the air, which to a certain extent scatters solar radiation, interferes with the maximum efficient operation of solar panels, then in space such a problem does not exist. Scientists are developing projects for giant orbital satellites with solar panels that will operate 24 hours a day. From them, energy will be transmitted to ground-based receiving devices. But this is a matter of the future, and for existing batteries, efforts are aimed at increasing energy efficiency and reducing the size of devices.

The principle of operation of a solar power plant at home

A solar power plant is a system consisting of panels, an inverter, a battery and a controller. The solar panel transforms radiant energy into electricity (as mentioned above). Direct current enters the controller, which distributes the current to consumers (for example, a computer or lighting). The inverter converts direct current into alternating current and powers most electrical household appliances. The battery stores energy that can be used at night.

How to calculate the required collector power

When calculating the required power of a solar collector, calculations are often mistakenly made based on the incoming solar energy in the coldest months of the year.

The fact is that in the remaining months of the year the entire system will constantly overheat. In summer, the temperature of the coolant at the outlet of the solar collector can reach 200°C when heating steam or gas, 120°C for antifreeze, 150°C for water. If the coolant boils, it will partially evaporate. As a result, it will have to be replaced.

Manufacturers recommend proceeding from the following figures:

provision of hot water supply no more than 70%;
provision of the heating system no more than 30%.

The rest of the required heat must be generated by standard heating equipment. Nevertheless, with such indicators, an average of about 40% is saved per year on heating and hot water supply.

The power generated by one tube of a vacuum system depends on the geographic location. The rate of solar energy falling per 1 m2 of land per year is called insolation. Knowing the length and diameter of the tube, you can calculate the aperture - the effective absorption area. It remains to apply the absorption and emission coefficients to calculate the power of one tube per year.

Calculation example:

The standard tube length is 1800 mm, the effective length is 1600 mm. Diameter 58 mm. Aperture is the shaded area created by the tube. Thus, the area of the shadow rectangle will be:

S = 1.6 * 0.058 = 0.0928m2

The efficiency of the middle tube is 80%, solar insolation for Moscow is about 1170 kWh/m2 per year. Thus, one tube will produce per year:

W = 0.0928 * 1170 * 0.8 = 86.86 kWh

It should be noted that this is a very rough estimate. The amount of energy generated depends on the orientation of the installation, angle, average annual temperature, etc. published econet.ru