This is powered by a solar battery. Portable solar battery - especially for tourists. Operating principle of solar panel

They have become so widespread that each user can order components and assemble and install photovoltaic panels with their own hands. Of course, the issue of price remains relevant, because solar panels are not a cheap option, but they are environmentally friendly. And the cost is getting cheaper every year. So everyone has probably come across the idea of using such a source of electricity, but not everyone knows the principle of operation of a solar battery.

Video about how a solar battery works

The principle of operation of a solar battery

To understand how a solar battery works, you need to understand what it consists of. Typically, a solar energy source consists of the following parts:

DC generator(aka solar panel)

Battery with charge control and inverter that converts current into alternating current

In its turn the panel consists of photoelectric converters which, speaking in simple language, transform solar energy into electrical energy. Most often these are polycrystalline or monocrystalline silicon batteries. The difference is in efficiency and production technology.

The operating principle of a solar power plant is the sequential interaction of a number of elements unified network. Elements are connected in solar panel sequentially and in parallel. This is done in order to increase power, voltage and current. Plus, such a connection will protect the remaining parts of the circuit in case of failure of one element.

The batteries are also riddled with so-called diodes. The operating principle of solar panels is based on these elements. Such diodes protect the panel during partial dimming. During such blackouts, the battery does not interrupt its operation, but produces a quarter less power. The bottom line is that diodes prevent solar cells from overheating, which during darkening begin to consume electricity instead of generating it.

Further Electricity is stored in batteries. And then it is sent to the system. Important point is that the number of parallel and series-connected elements in the solar panel is calculated in such a way that the voltage supplied to the batteries exceeds the voltage of the battery itself. Even taking into account the drawdown. In this case, the load current of the solar battery must provide a sufficient amount of charging current. This parameter must be taken into account when .

Another important factor in the operation of solar panels - useful power. Exactly this indicator reflects the cost-effectiveness of use for the user. This power is calculated based on the voltage and output current of the installation. And these indicators, in turn, depend on the strength of sunlight that falls directly on the panel. By the way, too high temperatures are not useful for the operation of solar panels. Indeed, with intense heating by the sun, the so-called electromotive force. However, the brighter the sunlight, the higher current is being produced.

Now a few formulas about the principle of operation of solar panels.

How does a solar panel work? For example, a solar battery is connected to a load with a measured resistance (Rн). Consequently, a current appears in the circuit (I). At the same time, the indicator I is formed in direct dependence on the quality of the converter in the circuit, the strength of solar illumination and resistance. Next we'll look at Un. Un- this is the voltage that is created at the terminals of solar panels. As a result, knowing these indicators, we can calculate the power that appears in the load on the installation: Pn = InUn

However, each panel has its own optimal resistance and it depends on the level of efficiency.

In cloudy weather, the battery charge naturally decreases due to less electricity generated by the panels.

During this process, the electricity is received by the receiver. In other words, batteries always operate either on charge or discharge. This interaction mechanism is controlled by the controller. Most often, the operation of batteries in a circuit is designed in such a way that they are very They quickly charge up to 80-90%, and then take a long time to collect the remaining charge.

Today, the most effective batteries for use in alternative energy supply systems are gel batteries. Such batteries do not require maintenance and are unpretentious in operating conditions. In this case, the service life usually reaches 10 years.

Controller, resistor and inverter Controller

necessary for connecting batteries to the network. It controls the charge. absorbs excess power generation capacity.

Inverter necessary for the normal supply of the electrical network, except in cases where it is necessary to power receivers that operate on direct voltage rather than alternating voltage.

Of course, it is difficult to understand all the intricacies of the work. But we hope you will find the answers on the pages of our website. More clear work solar cells can be understood from graphical diagrams.

Every second great amount Solar energy reaches the surface of our planet, giving life to all living things. A worthy challenge for inquiring minds is a solution that would make it serve the needs of people. And those who have invented the design of a solar battery capable of converting sunlight into electrical energy.

It is easier to understand how a solar battery works using the example of a design based on monocrystalline silicon.

Two layers of silicon with different physical properties form a thin wafer. The inner layer is monocrystalline pure silicon with p-type conductivity, which is coated on the outside with a layer of “contaminated” silicon. This could be, for example, an admixture of phosphorus. It has n-type conductivity. The back side of the plate is covered with a continuous metal layer.

The photocells are fixed in the frame in such a way that they can be replaced if they fail. The entire structure is covered with tempered glass or plastic, which protects it from negative impact external factors.

The principle of operation of a solar battery

As a result of the flow of charges at the boundary of the p- and n-layers, a zone of uncompensated positive charge is formed in the n-layer, and a zone of negative charge is formed in the p-layer, i.e. known to everyone from school course physics p-n junction. The potential difference that appears at the junction, the contact potential difference (potential barrier), prevents the passage of electrons from the p-layer, but freely allows minority carriers to pass in the opposite direction, which makes it possible to obtain a photo-emf when sunlight hits the photovoltaic cell.

When irradiated by sunlight, the absorbed photons begin to generate nonequilibrium electron-hole pairs. The electrons generated near the transition move from the p-layer to the n-region.

In a similar way, excess holes from the n layer enter the p-layer (Figure a). It turns out that a positive charge accumulates in the p-layer, and a negative one in the n-layer, causing voltage in external circuit(Figure b). The current source has two poles: positive - p-layer and negative - n-layer.

This is the basic operating principle of solar cells. The electrons thus seem to be running in circles, i.e. leave the p-layer and return to the n-layer, passing the load (battery).

Photoelectric outflow in a single-junction element is provided only by those electrons that have an energy higher than the width of a certain band gap. Those that have less energy do not participate in this process. This limitation can be removed by multilayer structures consisting of more than one solar cell, with different band gaps. They are called cascade, multi-junction or tandem. Their photovoltaic conversion is higher due to the fact that such solar cells operate with a wider solar spectrum. In them, photocells are arranged as the band gap decreases. The sun's rays hit the photocell with the widest area first, and the photons with the highest energy are absorbed.

Then, the photons transmitted by the upper layer reach the next element etc. In the field of cascade elements, the main direction of research is the use of gallium arsenide as one component or several. Such elements have a conversion efficiency of 35%. The elements are connected into a battery, since it is necessary to make a separate element big size(and therefore power) is not allowed by technical capabilities.

Solar cells can operate for a long time. They have proven themselves to be stable and reliable source energy, having been tested in space, where the main danger for them is meteor dust and radiation, which lead to the erosion of silicon elements. But, since on Earth these factors do not have such a negative effect on them, it can be assumed that the service life of the elements will be even longer.

Solar panels are already in the service of humans, serving as a power source for various devices, ranging from mobile phones to electric cars.

And this is already the second attempt by man to harness the limitless solar energy, forcing it to work for his own benefit. The first attempt was to create solar collectors, in which electricity was generated by heating water to boiling point with concentrated rays of the sun.

The advantage of solar panels is that they directly produce electricity, losing energy much less than solar multi-stage collectors, in which the process of obtaining it is associated with the concentration of the sun's rays, heating water, releasing steam that rotates a steam turbine, and only after that the generation of electricity by a generator. The main parameters of solar panels are, first of all, power. Then it is important how much energy they have.

This parameter depends on the capacity of the batteries and their number. The third parameter is peak power consumption, meaning the number of simultaneously possible connections devices. One more important parameters is the rated voltage on which the choice depends additional equipment: inverter, solar panel, controller, battery.

Types of solar panels

All solar panels appear at first glance to be the same - dark glass-covered elements with metal strips that conduct current, placed in an aluminum frame.

But, solar panels are classified according to the power of electricity they generate, which depends on the design and area of the panel (they can be miniature plates with a power of up to ten watts and wide “sheets” with a power of two hundred or more watts).

In addition, they differ in the type of photocells that form them: photochemical, amorphous, organic, and also those created on the basis of silicon semiconductors, whose photoelectric conversion coefficient is several times higher. Consequently, the power is greater (especially during sunny weather). A competitor to the latter may be a solar battery based on gallium arsenide. That is, there are five types of solar panels on the market today.

They differ in the materials used for their manufacture:

1. Panels made of polycrystalline photovoltaic cells, with the characteristic blue color of a solar panel, crystalline structure and efficiency of 12-14%.

Polycrystalline panel

2. Panels made from monocrystalline elements are more expensive, but also more efficient (efficiency - up to 16%).

3. Solar panels made of amorphous silicon, which have the lowest efficiency - 6-8%, but they generate the cheapest energy.

4. Panels made of cadmium telluride, created using film technologies (efficiency - 11%).

Panel based on cadmium telluride

5. Finally, solar panels based on CIGS semiconductor, consisting of selenium, indium, copper, gallium. The technologies for their production are also film, but the efficiency reaches fifteen percent.

In addition, solar panels can be flexible and portable.

Very convenient are flexible panels that can be easily rolled up, like regular paper. Although their cost is higher than their solid-state counterparts, they have occupied their niche in the market. They are mainly in demand among tourists and travelers who, in the absence of electrification, need to charge mobile gadgets. The main manufacturer of flexible batteries powered by solar energy is Sun Charger, which, by the way, recently updated its the lineup models 34 W and 9 W.

The first model is suitable for powering tablets, cell phones, video cameras, digital cameras, GPS, gel batteries 6 and 12 volts, i.e. it can meet the needs of several people during a hike.

SunCharger SC-9/14 - folded battery

She is in an open form

Battery features: compact folding design, operating in a temperature range from -50 to +70 degrees, weighing only 420 grams, equipped with anti-reflective coating, built-in LED, eyelets for fastening. The output jack is round (5.5 mm / 2.1 mm).

Electrical characteristics: working output voltage 13.5 V (standard 12V), no load – 19V; operating output current – 0.65 A; dimensions when folded and unfolded - 20.5x15x3 cm and 50x41.5x0.4 cm; output power – 8.6 W.

The second model SunCharger SC-34/18 is by far the most powerful in the line of flexible solar panels. It was developed specifically for universal drives (laptops), which have a charging input of, as a rule, 17-19 volts. Maximum power – 18V. It connects directly to the drives, ensuring perfect matching. It is clear that it is also suitable for less “gluttonous” drives, including twelve-volt lead-acid batteries used in cars.

The solar array produces 18V at its maximum power point and is directly connected to these storage devices. Thus, she is “perfectly” aligned with them.

Naturally, this battery is also suitable for charging less voracious consumers. As you know, there is never enough power. And also quietly charges 12 V lead acid batteries, including automobile ones (after a few hours of charging, you can already start the car). Its thickness is 4 cm (i.e. it has become a little larger), but the battery turned out to be even a little more compact than conventional 12 V batteries.

This was achieved due to the thinner fabric used in its production and laminated photocells of a larger area.

The same battery opened

In addition to the features characteristic of the previous model, here, in addition to the round connector, there is also a “mother” and “father” at the output.

Electrical characteristics: output power, as is clear from the markings, 34 W; operating output current – 1.9 A; dimensions 40x18x4 cm (folded) and 40x18x4 cm (opened). Output voltage – 18 V and 26 V (no load). The weight, of course, is much more - 1.7 kg.

Portable solar battery - especially for tourists

Everyone nowadays has electronic gadgets. It doesn’t matter that some have less and some have more. All of them need to be charged, and for this we need charging device. But this issue is especially acute for those who find themselves in places where there is no power supply. The only way out is solar panels. But their prices remain high, and the choice remains small. The best option, as is commonly believed, is a product of the Goal Zero company (although there are both Russian and Chinese products - as always raising doubts).

But it turned out that not everything that is made in China or Korea is bad. Particularly pleased with the solar battery was the YOLK company from Chicago, which began production of a compact solar Solar batteries Paper – the thinnest and lightest. Its weight is only 120 grams. But there are other advantages - a modular design that allows you to increase power. The solar battery looks like a plastic box, similar in size to an iPad, only twice as thin. There is a solar panel on its front side. There is an output for a laptop on the case and USB ports and for connecting other solar panels, as well as a flashlight. Inside this miracle box are batteries and a control board. You can charge the device from an outlet, and it can be a phone and two laptops at the same time. Of course, the device is also charged from the sun. As soon as light hits it, the indicator lights up. IN hiking conditions The solar panel is simply irreplaceable: it successfully charges everything necessary devices– phones are faster, laptops.

Portable solar panels are compact in size: They are even available in the form of keychains, which can be attached to anything. They were developed so that you could take them fishing, hiking, etc. They definitely have a flashlight so that at night you can illuminate the road, tent, etc., mounts that make it easy to place them on backpacks, kayaks, tents . It is very important that such a device has a built-in battery that allows you to charge devices at night.

Scientists are working to increase the efficiency, but so far solar panels made from monocrystalline elements are leading in this indicator. Consisting of several layers, monocrystalline panels are designed so that one of the layers absorbs green energy, another - red, and the third - blue. But, the cost of such panels is very high.

A solar battery, as you know, consists of several required parts. Its basis, like the engine of a car or the heart of a person, is a solar panel - a transparent rectangular box with dark squares of thinly sliced silicon inside. Silicon used in production, or rather its oxide (a compound with oxygen), is the main element in the production of solar cells.

The technologies underlying the production of solar panels are constantly being improved and consist of several stages.

At the first stage, raw materials are prepared: quartz sand is cleaned by calcining it with coke. As a result, it is freed from oxygen, turning into pieces of pure silicon, somewhat reminiscent of coal. Then, crystals are grown from it - the basis of solar panels, ordering the structure of silicon. To do this, pure silicon is lowered into a crucible and heated to high temperature, adding a seed to the molten lava. You can compare it with a sample of a future crystal, around which silicon of an ordered structure grows, layer by layer. After several hours of growth, a monosilicon crystal is obtained (or polycrystalline silicon, the production process of which is more expensive, which affects the price of solar panels made from it), resembling a large icicle. Then the cylindrical workpiece is converted into a parallelepiped. After this, the workpiece is cut into plates with a thickness of 100-200 microns (the thickness of three human hairs), they are tested, sorted and sent to the next stage of processing.
In the second stage the plate soldered into sections, from which blocks are formed on glass to eliminate the possibility of mechanical impact on the finished solar cells. Sections usually consist of 9-10 solar cells, blocks - of 4-6 sections.
Third stage involves laminating plates soldered into blocks with ethylene vinyl acetate film, and then a protective coating, which is carried out using a computer that monitors pressure, vacuum and temperature.
The fourth stage is final. During this process, the connection box and aluminum frame are installed. Testing is carried out again, during which the open circuit voltage, short circuit current, voltage and current of the maximum capacitance point are measured.

The leaders among enterprises producing solar panels are the following countries: China (Trina Solar, Yingli, Suntech companies), Japan (Sharp Solar) and the USA (First Solar), which not only produces them, but also participates in the design of solar stations and their construction. The most powerful solar power plant in the world, Agua Caliente in Arizona, is the work of this company. The construction of the largest solar power plant "Perovo" in Ukraine was carried out by an Austrian company (Activ Solar).

How much does a solar battery cost?

Selling solar panels is a profitable and promising business. Sales volume increases annually. First place in sales - Chinese manufacturers, whose products are characterized by low cost. This situation led to the bankruptcy of large German brands, which cost twice as much as Chinese solar panels.

The cost of solar panels depends on the manufacturer and power, and has a huge range - from 1800 UAH up to 9000 UAH (for Ukraine), from 5 thousand rubles to 30 thousand (For Russia). The cost of these SunCharger SC-9/14 and SunCharger SC-34/18 batteries is also high (you have to pay for excellent characteristics). It amounts accordingly 6100 and 20700 rubles. But, in comparison with the AcmePower 32 W flexible battery, the price for which is 27 thousand rubles, this battery is much cheaper.

Those who want to save money can purchase solar crystalline folding batteries at a price that is 2.5 times less.

conclusions

Fantastic ideas are gradually becoming reality. Let’s remember, for example, a microcalculator based on photocells, which once seemed like a curiosity that allowed you to not change the battery for years. The invention of recent years is a mobile phone with a built-in solar panel, cars and planes that move thanks to the same solar energy. In the future, solar panels will certainly become the main source of energy, finally “curing” all gadgets from “outlet addiction” and giving humanity cheap energy.

Application of solar panels

Using solar energy to create solar power plants is a very profitable and not so expensive source of electricity. Solar batteries are widely used not only in industry and other sectors, but also for individual needs.

Over time, solar panels become cheaper and that's it larger number people acquire them and use them as a source alternative energy. Solar panels power calculators, radios, and battery-powered flashlights that are recharged from a solar panel.

There's even Korean mobile phone, which can be charged from solar panels. Small portable power stations based on solar panels have appeared, which are used by tourists, fishermen, and hunters. Nowadays you won’t surprise anyone with a car with a solar panel on the roof.

How solar panels work

A solar panel consists of many photocells that, when illuminated by sunlight, create a potential difference. Now, by connecting these photocells in series, we will increase the DC voltage, and by connecting in parallel, we will increase the current.

Installation of solar panels

That is, by connecting photocells in series - in parallel, we can achieve high power solar panel. Also, batteries can be assembled in parallel and in series in a module and achieve significant increase voltage, current and power of such a module.

Operating principle of solar panel

In addition to solar panels, the circuit also has devices such as those necessary to control the battery charge; the inverter has the function of converting direct voltage into stable alternating voltage for electricity consumers. Batteries are designed to store electricity.

How do solar cells work?

Becquerel also proved that solar energy can be converted into electricity by illuminating special semiconductors. Later, these semiconductors began to be called photocells. A photocell consists of two layers of semiconductor with different conductivities. Contacts are soldered to these semiconductors on both sides for connection to the circuit. The semiconductor layer with n conductivity is the cathode, and the layer with p conductor is the anode.

Conductivity n is called electronic conductivity, and the layer p is called hole conductivity. Due to the movement of “holes” in the p layer during illumination, a current is created. The state of an atom that has lost an electron is called a “hole.” Thus, the electron moves along the “holes” and the illusion of the “holes” moving is created.

In reality, the "holes" do not move. The boundary of contact of conductors with different conductivities is called p-n junction ohm An analogue of a diode is created, which produces a potential difference when illuminated. When n conductivity is illuminated, electrons, receiving additional energy, begin to penetrate through p-n barrier transition.

The number of electrons and “holes” changes, which leads to a potential difference, and when the circuit is closed, a current appears. The magnitude of the potential difference depends on the size of the photocell, light intensity, and temperature. The main element of the first photocell was silicon. However high purity Silicon is difficult to obtain and it is not cheap.

When the n conductivity is illuminated, the electrons, receiving additional energy, begin to penetrate the barrier of the pn junction. The number of electrons and “holes” changes, which leads to a potential difference, and when the circuit is closed, a current appears

Therefore, they are now looking for a replacement for silicon. In new developments, silicon is replaced with a multilayer polymer with high efficiency up to 30%. But such solar panels are expensive and are not yet on the market. Efficiency of solar The battery life can be increased if you install them on the south side and at an angle of at least 30 degrees.

It is recommended to use a sun tracking device. This device moves the panels so that they receive the maximum possible illumination from the sun's rays from sunrise to sunset. At the same time, the efficiency of solar panels increases quite significantly.

The sun is an inexhaustible source of energy. It can be used by burning trees or heating water in solar heaters, converting the resulting heat into electricity. But there are devices that convert sunlight into electricity directly. These are solar panels.

Scope of application

There are three areas for using solar energy:

Energy saving. Solar panels allow you to abandon centralized power supply or reduce its consumption, as well as sell excess electricity to the power supply company.
Providing electricity to facilities to which connecting power lines is impossible or economically unprofitable. This could be a summer cottage or a hunting lodge located far from power lines. Such devices are also used to power lamps in remote areas of the garden or bus stops.
Power supply for mobile and portable devices. When hiking, fishing trips and other similar activities, there is a need to charge phones, cameras and other gadgets. Solar cells are also used for this.

Solar panels are convenient to use where electricity cannot be supplied

Principle of operation

Solar cell elements are silicon wafers 0.3 mm thick. On the side where the light hits, boron is added to the plate. This leads to the appearance of an excess number of free electrons. Phosphorus is added to the reverse side, which leads to the formation of “holes”. The boundary between them is called a p-n junction. When light hits the plate, it “knocks out” electrons reverse side. This is how a potential difference appears. Regardless of the size of the element, one cell develops a voltage of 0.7 V. To increase the voltage, they are connected in series, and to increase the current - in parallel.

Expert opinion

Alexey Bartosh

Specialist in repair and maintenance of electrical equipment and industrial electronics.

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In some designs, to increase power, lenses were installed above the elements or a system of mirrors was used. With decreasing battery costs, such devices have become obsolete.

The maximum efficiency of the panel, and therefore the power, is achieved when the light falls at an angle of 90 degrees. In some stationary devices, the battery rotates to follow the sun, but this greatly increases the cost and makes the design heavier.

The principle of operation of a solar battery

Advantages and disadvantages of using batteries

Solar panels, like any device, have advantages and disadvantages related to the principle of operation and design features.

Advantages of solar panels:

Autonomy. Allows you to provide electricity to remote buildings or lamps and work mobile devices in hiking conditions.
Economical. The light from the sun is used to generate electricity, for which you do not have to pay. Therefore, PV systems (photovoltaic systems) pay for themselves in 10 years, which is less than the service life of more than 30. Moreover, 25–30 years is guarantee period, and the photovoltaic power plant will continue to operate after it, bringing profit to the owner. Of course, it is necessary to take into account the periodic replacement of inverters and batteries, but still, using such a power plant helps save money.
Environmental friendliness. During operation, the devices do not pollute the environment and do not make noise, unlike power plants operating on other types of fuel.

In addition to its advantages, FES has disadvantages:

High price. Such a system is quite expensive, especially considering the price of batteries and inverters.
Long payback period. The funds invested in a photovoltaic power plant will pay off only after 10 years. This is more than the bulk of other investments.
Photovoltaic systems take up a lot of space - the entire roof and walls of a building. This violates the design of the structure. In addition, high-capacity batteries take up an entire room.
Uneven power generation. The power of the device depends on the weather and time of day. This is compensated by installing batteries or connecting the system to the network. This allows you to sell excess electricity to the electric company during the day during the day, and at night, on the contrary, connect the equipment to the centralized power supply.

Technical specifications: what to look for

The main parameter of a photocell system is power. The voltage of such an installation reaches its maximum in bright light and depends on the number of elements connected in series, which in almost all designs is 36. The power depends on the area of one element and the number of chains of 36 pieces connected in parallel.

In addition to the batteries themselves, it is important to choose a battery charging controller and an inverter that converts the battery charge into mains voltage, as well as the panels themselves.

Batteries have a permissible charging current that cannot be exceeded, otherwise the system will fail. Knowing the battery voltage, it is easy to determine the power required for charging. She must be more power solar power plant, otherwise on a sunny day some of the energy will be unused.

The controller provides charge to the batteries and must also have the power to fully utilize the sun's energy.

Equipment that receives energy from the solar power plant is connected to the inverter, so its power must correspond to the total power of electrical appliances.

Types of solar panels

In addition to size and power, the panels differ in the way the individual elements are made from silicon.

Appearance mono- and polycrystalline panels

Monocrystalline silicon elements

Solar cell cells made of monocrystalline silicon have a square shape with rounded corners. This is due to manufacturing technology:

a cylindrical crystal is grown from molten silicon of a high degree of purity;
after cooling, the edges of the cylinder are cut off, and the circle base takes the shape of a square with rounded corners;
the resulting block is cut into plates 0.3 mm thick;
boron and phosphorus are added to the plates and contact strips are glued to them;
A battery cell is assembled from ready-made elements.

The finished cell is fixed to the base and covered with glass that transmits ultraviolet rays or laminated.

Such devices are characterized by the highest efficiency and reliability, therefore they are installed in important places, for example, in spacecraft.

Multi-polycrystalline silicon photocells

In addition to solid crystal elements, there are devices in which solar cells are made of polycrystalline silicon. The production technology is similar. The main difference is that instead of a crystal round shape a rectangular block is used, consisting of large quantity small crystals of various shapes and sizes. Therefore, the elements are rectangular or square in shape.

Waste from the production of microcircuits and photocells is taken as raw material. This reduces the cost of the finished product, but degrades its quality. Such devices have lower efficiency - on average 18% versus 20–22% for monocrystalline batteries. However, the question of choice is quite complex. U different manufacturers the price of one kilowatt of power for monocrystalline and polycrystalline panels can be the same or in favor of any type of device.

Amorphous silicon photocells

IN last years Flexible batteries, which are lighter than rigid ones, have become widespread. Their manufacturing technology differs from the manufacturing technology of mono- and polycrystalline panels - thin layers of silicon with additives are sprayed onto a flexible base, usually a steel sheet, until the required thickness is achieved. After this, the sheets are cut, conductive strips are glued to them, and the entire structure is laminated.

Amorphous silicon solar cells

The efficiency of such batteries is approximately 2 times less than that of rigid structures, however, they are lighter and more durable due to the fact that they can be bent.

Such devices are more expensive than conventional ones, but there is no alternative to them in camping conditions, when lightness and reliability are of primary importance. The panels can be sewn onto a tent or backpack and charge the batteries while moving. When folded, such devices resemble a book or a rolled-up drawing that can be placed in a case resembling a tube.

In addition to charging mobile devices on the go, flexible panels are installed in electric cars and electric planes. On the roof, such devices follow the curves of the tiles, and if glass is used as a base, it takes on a tinted appearance and can be inserted into a house window or greenhouse.

Charge controller for solar panels

U direct connection panels to the battery have disadvantages:

A battery with a nominal voltage of 12 V will only charge when the voltage at the output of the photocells reaches 14.4 V, which is close to the maximum. This means that part of the time the batteries will not be charged.
The maximum voltage of photocells is 18 V. At this voltage, the battery charging current will be too high, and they will quickly fail.

In order to avoid these problems, it is necessary to install a charge controller. The most common designs are PWM and MPRT.

PWM charge controller

Operation of the PWM controller ( pulse width modulation– English pulse-width modulation (PWM) maintains a constant output voltage. This provides maximum degree battery charge and protection from overheating during charging.

MPRT charge controller

MPPT controller (Maximum power point tracker - tracking the point of maximum power) provides such a value of output voltage and current that allows you to maximize the potential of the solar battery, regardless of the brightness of sunlight. At reduced brightness light, it raises the output voltage to the level necessary to charge the batteries.

Such a system is found in all modern inverters and charging controllers

Types of batteries used in batteries

Different kinds batteries that can be used for solar panels

Batteries are an important element of the 24-hour solar power supply system for a home.

Such devices use the following types batteries:

starter;
gel;
AGM batteries;
flooded (OPZS) and sealed (OPZV) batteries.

Other types of batteries, such as alkaline or lithium, are expensive and rarely used.

All these types of devices must operate at temperatures from +15 to +30 degrees.

Starter batteries

The most common type of battery. They are cheap, but have a high self-discharge current. Therefore, after a few cloudy days, the batteries will be discharged even without load.

The disadvantage of such devices is that gas is released during operation. Therefore, they must be installed in a non-residential, well-ventilated area.

In addition, the service life of such batteries is up to 1.5 years, especially with multiple charge-discharge cycles. Therefore, in the long run, these devices will be the most expensive.

Gel batteries

Gel batteries are maintenance-free products. There is no gas emission during operation, so they can be installed in living rooms and rooms without ventilation.

Such devices provide high output current, have high capacitance and low self-discharge current.

The lack of such devices in high price and short service life.

AGM batteries

These batteries have a short service life, however, they have many advantages:

no gas emission during operation;
small in size;
a large number (about 600) charge-discharge cycles;
fast (up to 8 hours) charge;
works well even when not fully charged.

AGM battery from inside

Flooded (OPZS) and sealed (OPZV) batteries

Such devices are the most reliable and have the longest service life. They have low current self-discharge and high energy intensity.

These qualities make such devices the most popular for installation in photocell systems.

How to determine the size and number of photocells?

The required size and number of photocells depends on the voltage, current and power to be drawn from the battery. The voltage of one element on a sunny day is 0.5 V. When it is cloudy it is much lower. Therefore, to charge 12 V batteries, 36 photocells are connected in series. Accordingly, 24 V batteries require 72 cells, and so on. Their total number depends on the area of one element and the required power.

One square meter The battery area, taking into account efficiency, can produce approximately 150 W. More precisely, it can be determined from meteorological reference books showing the amount of solar radiation at the installation site of a solar power plant or on the Internet. The efficiency of the device is indicated in the passport.

When making photovoltaics with your own hands required amount elements is determined by the power of one element in a given climate, taking into account efficiency.

The calculation of the number of solar panels is based on required electricity

Efficiency of solar panels in winter

Despite the fact that the sun rises lower in winter, the flow of light decreases slightly, especially after snow falls.

There are three main reasons why solar cells are less efficient in winter:

The angle of incidence of the rays changes. In order to maintain power, the angle of the battery must be changed at least once a season, and preferably every month.
Snow, especially wet snow, sticks to the surface of the device. It must be removed immediately after falling out.
In winter, there is less daylight hours and more cloudy days. It is impossible to change this, so you have to calculate the battery power based on the winter minimum.

Installation Rules

The maximum power of the panel is achieved in a position in which Sun rays fall perpendicularly. This must be taken into account during installation. It is also important to consider what time of day the cloudiness is minimal. If the angle of the roof and its position do not meet the requirements, it can be corrected by adjusting the base.

There should be an air gap of 15–20 centimeters between the battery and the roof. This is necessary to allow rain to flow through and to prevent overheating.

Photovoltaic cells do not perform well in the shade, so you should avoid placing them in the shade of buildings or trees.

Power plants made from solar photocells are a promising environmentally friendly source of energy. Their widespread use will solve problems with energy shortages, pollution environment and the greenhouse effect.

Nowadays, almost everyone can collect and have their own independent source of electricity using solar panels(in scientific literature they are called photovoltaic panels).

Over time, expensive equipment is offset by the opportunity to receive free electricity. It is important that solar panels are an environmentally friendly source of energy. In recent years, prices for photovoltaic panels have fallen tens of times and they continue to decline, which indicates great prospects for their use.

IN classic look such a source of electricity will consist of the following parts: directly, a solar battery (DC generator), a battery with a charge control device and an inverter that converts D.C. into variable.

Solar panels consist of a set solar cells (photovoltaic converters), which directly convert solar energy into electrical energy.

Most solar cells are made from silicon, which is quite expensive. This fact will determine the high cost of electrical energy, which is obtained by using solar panels.

There are two common types of photovoltaic converters: those made of monocrystalline and polycrystalline silicon. They differ in production technology. The former have an efficiency of up to 17.5%, and the latter - 15%.

The most important technical parameter of a solar battery, which has a major impact on the efficiency of the entire installation, is its useful power. It is determined by voltage and output current. These parameters depend on the intensity of sunlight hitting the battery.

E.m.f. (electromotive force) of individual solar cells does not depend on their area and decreases when the battery is heated by the sun, by approximately 0.4% per 1 g. C. The output current depends on the intensity of solar radiation and the size of the solar cells. The brighter the sunlight, the more current is generated by the solar cells. Charging current and the output power in cloudy weather decreases sharply. This occurs by reducing the current supplied by the battery.

If a battery illuminated by the sun is connected to any load with resistance Rн, then a electricity I, the value of which is determined by the quality of the photoelectric converter, lighting intensity and load resistance. The power Pн, which is released in the load, is determined by the product Pн = InUn, where Un is the voltage at the battery terminals.

The greatest power is released in the load at a certain optimal resistance Ropt, which corresponds to the highest efficiency of converting light energy into electrical energy. Each converter has its own Ropt value, which depends on the quality, size of the working surface and degree of illumination.

Solar battery consists of individual solar cells that are connected in series and parallel in order to increase the output parameters (current, voltage and power). At serial connection elements, the output voltage increases, and in parallel, the output current increases. In order to increase both current and voltage, these two connection methods are combined. In addition, with this connection method, the failure of one of the solar cells does not lead to the failure of the entire chain, i.e. increases the reliability of the entire battery.

Thus, A solar battery consists of parallel-series connected solar cells. The value of the maximum possible current supplied by the battery is directly proportional to the number of parallel connected ones, and the emf. - series-connected solar cells. So, by combining connection types, a battery with the required parameters is assembled.

The solar cells of the battery are shunted by diodes. Usually there are 4 of them - one for each ¼ of the battery. Diodes protect parts of the battery from failure that for some reason are darkened, that is, if at some point in time the light does not fall on them. The battery temporarily generates 25% less output power than with normal sun illumination of the entire surface of the battery.

In the absence of diodes, these solar cells will overheat and fail, since during darkening they turn into current consumers (the batteries are discharged through the solar cells), and when diodes are used, they are shunted and no current flows through them. Diodes must be low-resistance to reduce voltage drop across them. For these purposes in Lately Schottky diodes are used.

The resulting electrical energy is stored in batteries and then transferred to the load. - chemical current sources. The battery is charged when a potential is applied to it that is greater than the battery voltage.

The number of solar cells connected in series and parallel must be such that the operating voltage supplied to the batteries, taking into account the voltage drop in the charging circuit, slightly exceeds the battery voltage, and the load current of the battery provides the required amount of charging current.

For example, to charge a 12 V lead battery, you need to have a solar battery consisting of 36 cells.

In weak sunlight, the battery charge decreases and the battery transfers electrical energy to the electrical receiver, i.e. Rechargeable batteries constantly operate in discharge and recharge mode.

This process is controlled. Cyclic charging requires a constant voltage or constant charging current.

When there is good lighting, the battery is quickly charged to 90% of its rated capacity, and then at a slower charge rate to full capacity. Switching to a lower charging rate is performed by the charger controller.

The most effective is the use of special batteries (the battery uses sulfuric acid as an electrolyte) and lead batteries, which are made using AGM technology. These batteries are not needed special conditions installation and no maintenance required. The certified service life of such batteries is 10 - 12 years with a discharge depth of no more than 20%. Batteries should never be discharged below this value, otherwise their service life will be drastically reduced!

The battery is connected to the solar panel through a controller that controls its charge. When the battery is charged to full capacity, a resistor is connected to the solar panel, which absorbs excess power.

In order to convert DC voltage from the battery into AC voltage, which can be used to power most electrical receivers together with solar batteries can be used special devices - .

Without using an inverter, a solar battery can be used to power electrical receivers operating at constant voltage, incl. various portable equipment, energy-saving light sources, for example, the same LED lamps.