The principle of operation and the device of solar panels

The principle of operation of the solar battery

The device is designed to directly convert the sun's rays into electricity. This action is called the photoelectric effect. Semiconductors (silicon wafers), which are used to make elements, have positive and negative charged electrons and consist of two layers, the n-layer (-) and the p-layer (+). Excess electrons under the influence of sunlight are knocked out of the layers and occupy empty places in another layer. This causes free electrons to constantly move, moving from one plate to another, generating electricity that is stored in the battery.

How a solar battery works depends largely on its design. Solar cells were originally made from silicon.They are still very popular, but since the process of cleaning silicon is quite laborious and costly, models are being developed with alternative photocells from compounds of cadmium, copper, gallium and indium, but they are less productive.

The efficiency of solar panels has increased with the development of technology. Today, this figure has increased from one percent, which was recorded at the beginning of the century, to more than twenty percent. This allows us to use panels today not only for domestic needs, but also for production.

Specifications

The device of the solar battery is quite simple, and consists of several components:

Directly solar cells / solar panel;

An inverter that converts direct current to alternating current;

Battery level controller.

Buy batteries for solar panels should be based on the required functions. They store and distribute electricity. Storage and consumption occurs throughout the day, and at night the accumulated charge is only consumed. Thus, there is a constant and continuous supply of energy.

Excessive charging and discharging of the battery will shorten its useful life. The solar battery charge controller automatically suspends the accumulation of energy in the battery when it has reached its maximum parameters, and turns off the load of the device when it is heavily discharged.

(Tesla Powerwall - a 7 kW solar panel battery - and home charging for electric vehicles)

The grid inverter for solar panels is the most important design element. It converts the energy received from the sun's rays into alternating current of various capacities.Being a synchronous converter, it combines the output voltage of electric current in frequency and phase with a stationary network.

Photocells can be connected both in series and in parallel. The latter option increases the power, voltage and current parameters and allows the device to work even if one element loses functionality. Combined models are made using both schemes. The service life of the plates is about 25 years.

Choosing solar panels for a private house

Before buying solar panels for a private home, find out:

• Daily consumption of electricity in the room;
• A place for installing panels (directed to the south, while there should be no shadow on them and the appropriate angle of inclination should be set);
• Batteries are placed in a warm room at this temperature up to 25 degrees Celsius;
• Take into account the peak loads of electrical appliances;
• Seasonal or permanent use of the system.

For regions with high light activity, monocrystalline batteries are best suited. For a summer residence or a personal plot, if seasonal use is planned, micromorphic polycrystalline models are best suited. They are relatively inexpensive, they perceive diffused, side light well and work at an angle in cloudy weather.

Calculation example

The suburban area consumes 3-6 kWh of electrical energy, but this figure may be higher when using a large number of electrical appliances or additional lighting at home. A three-story cottage consumes from 20 to 50 kWh and even more. Based on the information provided, we will make a calculation.

The energy intensity of the cottage is 7 kW (including losses). If the house is located in the South, where there is enough sunlight for energy supply, then about 20 batteries will be needed. The working power of one panel is 400 watts. This amount is enough to supply energy to a suburban area where a family of 4-6 people permanently lives.

Installation

When buying products of a particular company, you get detailed wiring diagrams and instructions, and you can install uninterruptible power supplies and solar panels with your own hands. But if you do not want to deal with the installation and configuration of systems or have never done this before, then entrust this work to professionals.

Specialists go to the site and perform installation and commissioning of equipment in a short time. On average, installation of a solar power plant takes from one to four days, depending on the complexity of the system, and an uninterruptible power supply is installed within one to two days.

Installation of solar modules takes place according to a pre-approved scheme, and all components of the system; batteries, charge controllers and converters are installed in a convenient and accessible place for you. The power plant is easy to maintain. Solar panels have a smooth surface from special glass, which does not allow snow and dust to accumulate. Batteries used for solar systems are maintenance-free and have a lifespan of up to 10 years.

Tips

Experts give several recommendations on how to properly lay and connect solar panels.

Most often, products using alternative energy sources are mounted on the roof or on the walls of housing construction, less often they use special reliable supports.

In any case, any blackouts should be completely excluded, that is, the batteries should be oriented in such a way that they do not fall under the shadow of tall trees and neighboring buildings.
The installation of a set of plates is carried out in rows, their arrangement is parallel, in this regard, it is extremely important to ensure that the higher rows do not cast a shadow on those below. This requirement is very important, since complete or partial shading provokes a reduction and even a complete cessation of any energy production, in addition, the effect of the formation of "reverse currents" can occur, which often causes equipment breakdown.

Proper orientation to sunlight is critical to the efficiency and effectiveness of the panels.

It is very important that the surface receives all possible UV rays. The correct orientation is calculated based on data on the geographical location of the building

For example, if the panels are mounted on the north side of the building, then the panels should be oriented to the south.
Equally important is the overall angle of inclination of the structure, it is also determined by the geographical orientation of the structure.Experts calculated that this indicator should correspond to the latitude of the location of the house, and since the sun, depending on the time of year, changes its location above the horizon several times, it makes sense to consider adjusting the final installation angle of the batteries. Usually the correction does not exceed 12 degrees.

• The batteries must be laid in such a way as to provide free access to them, since in the cold winter time it will be necessary to periodically clean them from attacking snow, and in the warm season - from rain stains, which significantly reduce the efficiency of using batteries.
• To date, there are many Chinese and European models of solar panels on sale, which differ in cost, so everyone can install the model that is optimal for their budget.

In conclusion, it should be noted that our planet will receive the greatest benefit from the use of solar panels, since this energy source does not cause absolutely any harm to the environment. If you, as a consumer, care about the future of our Earth, the potential of its land resources and the conservation of natural resources, then solar panels are the best choice.

How to install a solar battery on the roof of the house, see the following video.

Conclusion on the topic

A professional approach to the installation of a solar power plant will allow you to take into account all the factors, nuances and avoid annoying mistakes.

General rules for installing solar panels

When installing solar panels, it is necessary to take into account 5 factors, the combination of which ultimately determines the place and method of installation:

1. Heat dissipation
2. Shadow
3. Orientation
4. Incline
5. Availability for service

As mentioned above, heat dissipation plays an important role in maintaining the performance of batteries. It is imperative to leave a ventilation gap between the panel and the installation plane, and the larger it is, the better. Usually, when mounting a frame or frame for mounting modules between the panel and the plane, 5-10 centimeters are left. Maximum ventilation is ensured when mounted on a separate frame or rod.

Any shadow falling on the battery from trees or buildings "turns off" the shaded cell, which accelerates the degradation of expensive single-crystal modules and completely stops power generation in polycrystalline ones. Manufacturers offer various ways to minimize the risk of a “hot spot” due to interruption of the electrical circuit, which must be considered when purchasing. But it is better to install the battery in such a way that the "hard" shadow cannot fall on it in any way. A "soft" shadow due to fog, clouds or smog does not harm the battery, it just reduces power output.

You need to orient the battery to the south - so the insolation will be maximum. All other installation methods are compromises, and it is better not to consider them. It would be unreasonable to spend tens of thousands of rubles on the purchase of modules, but it would be unreasonable to orient the battery not to the sun. Insolation maps for various regions of the Russian Federation are published on the Internet and are publicly available. The central strip of Russia is mainly located in the 2nd zone of insolation, where from 1 sq. meters of a properly installed ideal solar module can produce up to 3 kWh / day.

The availability of a battery for quick cleaning of the surface allows you to perform this simple operation without the involvement of specialists.In winter, the surface must be freed from snow, in summer - from dust and dirt caused by wind and rain. If there is an object under construction nearby, then the surface of the modules will have to be cleaned daily. The easiest way to do this is with a water jet from a hose or any window cleaning brush.

How to achieve maximum efficiency

When buying solar panels for your home, it is very important to choose a design that can provide your home with sufficient power. It is believed that the efficiency of solar panels in cloudy weather is approximately 40 W per 1 square meter per hour.

In fact, in cloudy weather, the light power at ground level is approximately 200 watts per square meter, but 40% of sunlight is infrared radiation, to which solar panels are not susceptible. It is also worth considering that battery efficiency rarely exceeds 25%.

Sometimes the energy from intense sunlight can reach 500 W per square meter, but the calculations should take into account the minimum figures, which will make the autonomous power supply system uninterrupted.

Every day the sun shines for an average of 9 hours, if we take the annual average. In one day, a square meter of the surface of the converter is capable of generating 1 kilowatt of electricity. If approximately 20 kilowatts of electricity are consumed per day by the residents of the house, then the minimum area of ​​​​solar panels should be approximately 40 square meters.

However, such an indicator of electricity consumption in practice is rare. As a rule, tenants will use up to 10 kW per day.

If we talk about whether solar panels work in winter, then it is worth remembering that at this time of the year the duration of daylight hours is greatly reduced, but if you provide the system with powerful batteries, then the energy received per day should be sufficient, taking into account the presence of a backup battery.

When choosing a solar battery, it is very important to pay attention to the capacity of the batteries. If you need solar panels that work at night, then the capacity of the backup battery plays a key role. Also, the device must be resistant to frequent recharging.

Also, the device must be resistant to frequent recharging.

Despite the fact that the cost of installing solar panels can exceed 1 million rubles, the costs will pay off within a few years, since solar energy is absolutely free.

How does a solar battery work

All living things on earth arose thanks to the energy of the sun. Every second, a huge amount of energy comes to the surface of the planet in the form of solar radiation. While we are burning thousands of tons of coal and petroleum products to heat our homes, countries closer to the equator are languishing in the heat. To use the energy of the sun for human needs is a worthy task for inquisitive minds. In this article, we will consider the design of a direct converter of sunlight into electrical energy - a solar cell.

The thin wafer consists of two layers of silicon with different physical properties. The inner layer is pure single-crystal silicon with hole conductivity. Outside, it is covered with a very thin layer of "contaminated" silicon, for example, with an admixture of phosphorus. A solid metal contact is applied to the back side of the plate.At the boundary of the n- and p-layers, as a result of the overflow of charges, depleted zones are formed with an uncompensated positive volume charge in the n-layer and volume negative charge in p-layer. These zones together form a p-n junction.

The potential barrier that arises at the junction prevents the passage of the majority charge carriers, i.e. electrons from the side of the p-layer, but freely pass minor carriers in opposite directions. This property of p-n junctions determines the possibility of obtaining photo-emf when irradiating solar cells with sunlight. When the SC is illuminated, the absorbed photons generate non-equilibrium electron-hole pairs. Electrons generated in the p-layer near the p-n junction approach the p-n junction and are carried out to the n-region by the electric field existing in it.

Similarly, excess holes created in the n-layer are partially transferred to the p-layer. As a result, the n-layer acquires an additional negative charge, and the p-layer acquires a positive one. The initial contact potential difference between the p- and n-layers of the semiconductor decreases, and a voltage appears in the external circuit. The negative pole of the current source corresponds to the n-layer, and the p-layer to the positive.

Most modern solar cells have a single p-n junction. In such an element, free charge carriers are created only by those photons whose energy is greater than or equal to the band gap. In other words, the photoelectric response of a single junction cell is limited to the part of the solar spectrum whose energy is higher than the band gap, and photons of lower energy are not used. This limitation can be overcome by multilayer structures of two or more SCs with different band gaps.Such elements are called multi-junction, cascade or tandem. Since they work with a much larger portion of the solar spectrum, they have higher photovoltaic conversion efficiency. In a typical multi-junction solar cell, single photocells are arranged one behind the other so that sunlight hits the cell with the largest bandgap first, while the photons with the highest energy are absorbed.

Batteries do not work from sunlight, but from sunlight in principle. Electromagnetic radiation reaches the earth at any time of the year. Just in cloudy weather, less energy is produced. For example, we installed autonomous solar-powered lights. Of course, there are short periods when the batteries do not have time to fully charge. But in general, this does not happen so often during the winter.

Interestingly, even if snow falls on the solar panel, it still continues to convert solar energy. And due to the fact that the photocells heat up, the snow itself thaws. The principle is the same as heating the glass of a car.

Perfect winter weather for a solar battery frosty cloudless day. Sometimes on such days even generation records can be arranged.

In winter, the efficiency of the solar panel drops. In Moscow and the Moscow region, on average, it produces 8 times less electricity per month. Let's say, if in summer the operation of a refrigerator, a computer and overhead lighting of a house requires 1 kW of energy, then in winter it is better to stock up on 2 kW for reliability.

At the same time, in the Far East, the duration of sunshine is longer, the efficiency is reduced by only one and a half to two times. And, of course, the further south, the smaller the difference between winter and summer.

The angle of inclination of the modules is also important. You can set the universal angle for the whole year. And you can change every time, depending on the season. This is not done by the owners of the house, but by specialists who go to the site.

Solar connection options

Solar panels are made up of several individual panels. To increase the output parameters of the system in the form of power, voltage and current, the elements are connected to each other, applying the laws of physics.

The connection of several panels to each other can be performed using one of three solar panels mounting schemes:

• parallel;
• consistent;
• mixed.

The parallel circuit involves connecting terminals of the same name to each other, in which the elements have two common nodes of convergence of conductors and their branching.

With a parallel circuit, the pluses are connected to the pluses, and the minuses to the minuses, as a result of which the output current increases, and the output voltage remains within 12 volts

The value of the maximum possible output current in a parallel circuit is directly proportional to the number of connected elements. The principles for calculating the quantity are given in the article we recommend.

The serial circuit involves the connection of opposite poles: the "plus" of the first panel to the "minus" of the second. The remaining unused "plus" of the second panel and the "minus" of the first battery are connected to the controller located further along the circuit.

This type of connection creates conditions for the flow of electric current, in which there is only one way to transfer the energy carrier from the source to the consumer.

With a serial connection, the output voltage increases and reaches 24 volts, which is enough to power portable equipment, LED lamps and some electrical receivers

A series-parallel or mixed circuit is most often used when it is necessary to connect several groups of batteries. By applying this circuit, both voltage and current can be increased at the output.

With a series-parallel connection scheme, the output voltage reaches a mark, the characteristics of which are most suitable for solving the bulk of household tasks

This option is also beneficial in the sense that in the event of failure of one of the structural elements of the system, other connecting chains continue to function. This significantly increases the reliability of the entire system.

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Connecting Solar Cells

Number of panels depending on needs

Serial connection of solar appliances

Direct connection to lighting fixtures

The principle of assembling a combined circuit is based on the fact that the devices within each group are connected in parallel. And the connection of all groups in one circuit is carried out sequentially.

By combining different types of connections, it will not be difficult to assemble a battery with the necessary parameters.The main thing is that the number of connected cells should be such that the operating voltage supplied to the batteries, taking into account its drop in the charging circuit, exceeds the voltage of the batteries themselves, and the load current of the battery at the same time provides the required amount of charging current.