The effective conversion of free rays of the sun into energy that can be used to power housing and other facilities is the cherished dream of many apologists for green energy.
But the principle of operation of the solar battery, and its efficiency are such that there is no need to talk about the high efficiency of such systems. It would be nice to have your own additional source of electricity. Is not it? Moreover, even today in Russia, with the help of solar panels, a considerable number of private households are successfully supplied with “free” electricity. You still don't know where to start?
Below we will tell you about the device and the principles of operation of the solar panel, you will find out what the efficiency of the solar system depends on. And the videos posted in the article will help to personally assemble the solar panel from photocells.
Solar panels: terminology
In the subject of "solar energy" there are a lot of nuances and confusion. It is often difficult for beginners to understand all unfamiliar terms at first. But without this, engaging in solar energy, acquiring equipment for generating “solar” current, is unreasonable.
Unknowingly, you can not only choose the wrong panel, but simply burn it when connected or extract too little energy from it.
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Installation from solar panels allows you to rationally use the free, moreover, inexhaustible energy of sunlight
Miniature power plants assembled from solar panels will provide energy to non-electrified objects and houses located in regions with interruptions in the supply of electricity
Installations that process UV radiation into electricity occupy a minimum of space. they are located on the roofs of houses, outbuildings, garages, arbors, verandas. Less commonly, they are located in open areas not occupied by buildings and plantings.
Solar panels are indispensable equipment for travel lovers. It will provide energy away from power sources
The use of solar energy will provide an opportunity to significantly reduce the cost of maintaining summer cottages and country houses. you can assemble and install a cost-effective system without difficulty with your own hands
The solar panels located at the stern of the yacht, the deck of the ship or the bow of the boat will provide electric power, thanks to which it is possible to maintain stable communication with the shore
A portable solar panel with a battery eliminates the occurrence of extreme situations far from settlements, guarantees the charging of mobile devices to communicate with loved ones
Lightweight, compact, solar-powered chargers specially designed for hiking will provide energy for phones, walkie-talkies, tablets and media technology
Rational use of natural resources
Energy supply to non-electrified facilities
Installation of solar panels on the roof
Camping Mobile Solar Battery
Independent installation in the suburban area
Power generator in boat trips
Portable solar panel with battery
Minimum space-saving device
First you need to understand the existing types of equipment for solar energy. Solar panels and solar collectors are two fundamentally different devices. Both of them transform the energy of the rays of the sun.
However, in the first case, the consumer receives electrical energy at the outlet, and in the second case the thermal energy in the form of a heated coolant, i.e. Solar panels are used for heating a house.
The maximum return from the solar panel can be obtained only by knowing how it works, what components and components it consists of and how it all connects correctly
The second nuance is the concept of the term “solar battery” itself. Typically, the word "battery" refers to some kind of energy storage device. Or a banal heating radiator comes to mind. However, in the case of solar batteries, the situation is radically different. They do not accumulate anything in themselves.
The solar panel generates a constant electric current. To convert it to a variable (used in everyday life), an inverter must be present in the circuit
Solar panels are designed exclusively for generating electric current. It, in turn, accumulates to supply the house with electricity at night, when the sun goes down over the horizon, already in the batteries present in addition to the object’s energy supply scheme.
The battery here is implied in the context of a certain combination of the same type of components assembled into a single whole. In fact, it's just a panel of several identical photocells.
The internal structure of the solar battery
Gradually, solar panels are becoming cheaper and more efficient. Now they are used to recharge batteries in streetlights, smartphones, electric cars, private homes and satellites in space. Of these, they even began to build full-fledged solar power plants (SES) with large volumes of generation.
The solar battery consists of many photocells (photovoltaic converters of photovoltaic cells), which convert the energy of photons from the sun into electricity
Each solar battery is arranged as a block of an nth number of modules that combine semiconductor photocells connected in series. To understand the principles of operation of such a battery, it is necessary to understand the operation of this final link in the solar panel device created on the basis of semiconductors.
Types of crystals of photocells
There are a lot of options for solar cells from different chemical elements. However, most of them are development in the initial stages. So far, only silicon-based solar cell panels are currently being produced on an industrial scale.
Silicon semiconductors are used in the manufacture of solar cells because of their low cost, they cannot boast of particularly high efficiency
A common solar cell in a solar panel is a thin plate of two silicon layers, each of which has its own physical properties. This is a classic semiconductor pn junction with electron-hole pairs.
When photons enter the PEC between these layers of the semiconductor due to the inhomogeneity of the crystal, a gate photo-emf is formed, resulting in a potential difference and an electron current.
Silicon wafers of solar cells differ in manufacturing technology for:
- Monocrystalline.
- Polycrystalline.
The former have a higher efficiency, but the cost of their production is higher than that of the latter. Externally, one option from another on the solar panel can be distinguished by shape.
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Helio-power station in a suburban area
Monocrystalline Solar Cells
Appearance of solar cells on single crystals
Monocrystalline Solar Unit
Supply of ready-to-install solar panel
Polycrystalline Solar Cell
Polycrystalline Solar Cell Battery
DIY solar cell manufacturing
Single-crystal PECs have a homogeneous structure; they are made in the form of squares with cut corners. In contrast, polycrystalline elements have a strictly square shape.
Polycrystals are obtained by gradually cooling molten silicon. This method is extremely simple, therefore such photocells are inexpensive.
But productivity in terms of generating electricity from sunlight they rarely exceed 15%. This is due to the “impurity” of the obtained silicon wafers and their internal structure. Here, the purer the p-layer of silicon, the higher the efficiency of the PEC from it.
The purity of single crystals in this respect is much higher than that of polycrystalline analogs. They are made not from molten, but from an artificially grown whole silicon crystal. The photovoltaic conversion coefficient of such solar cells already reaches 20-22%.
In a common module, individual photocells are assembled on an aluminum frame, and to protect them from above, they are closed with durable glass, which does not interfere with sunlight at all
The upper layer of the solar cell plate facing the sun is made of the same silicon, but with the addition of phosphorus. It is the latter that will be the source of excess electrons in the pn junction system.
The development of flexible panels with amorphous photoelectric silicon has become a real breakthrough in the field of using solar energy:
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Flexible solar option
Flexible photocell sticker on the blinds
Flexible mobile phone charger
Resistant to mechanical stress
The principle of operation of the solar panel
When sunlight falls on a photocell, nonequilibrium electron-hole pairs are generated in it. Excess electrons and "holes" are partially transferred through the pn junction from one semiconductor layer to another.
As a result, voltage appears in the external circuit. In this case, a positive pole of the current source is formed at the contact of the p-layer, and a negative pole at the n-layer.
The potential difference (voltage) between the contacts of the photocell appears due to a change in the number of “holes” and electrons from different sides of the p-n junction as a result of irradiation of the n-layer by solar rays
The photocells connected to an external load in the form of a battery form a vicious circle with it. As a result, the solar panel works like a kind of wheel along which electrons “run” along proteins. And the rechargeable battery is gradually gaining charge.
Standard silicon photovoltaic cells are single junction cells. The transfer of electrons into them occurs only through one p-n junction with a zone of this transition limited in photon energy.
That is, each such photocell is capable of generating electricity only from a narrow spectrum of solar radiation. All other energy is wasted. Therefore, the efficiency of solar cells is so low.
To increase the efficiency of solar cells, silicon semiconductor elements for them have recently been made multi-junction (cascade). There are already several transitions in the new FEP. Moreover, each of them in this cascade is designed for its own spectrum of sunlight.
The total efficiency of converting photons to electric current in such photocells ultimately increases. But their price is much higher. Here, either ease of manufacture with low cost and low efficiency, or higher returns coupled with high cost.
The solar battery can work both in summer and in winter (it needs light, not heat) - the less cloudiness and the sun shines brighter, the more the solar panel will generate an electric current
During operation, the photocell and the entire battery gradually heats up. All the energy that did not go to the generation of electric current is transformed into heat. Often the temperature on the surface of the heliopanel rises to 50–55 ° С. But the higher it is, the less efficient the photovoltaic cell works.
As a result, the same model of a solar battery generates less current in heat than in cold weather. Photocells show maximum efficiency on a clear winter day. Two factors affect this - a lot of sun and natural cooling.
Moreover, if snow falls on the panel, it will continue to generate electricity anyway. Moreover, snowflakes do not even have time to lie down on it, melted from the heat of heated photocells.
Solar battery efficiency
One photocell even at noon in clear weather gives out quite a bit of electricity, only enough for the LED flashlight to work.
To increase the output power, several solar cells are combined in a parallel circuit to increase the DC voltage and in series to increase the current strength.
The effectiveness of solar panels depends on:
- air temperature and the battery itself;
- correct selection of load resistance;
- angle of incidence of sunlight;
- presence / absence of anti-reflective coating;
- power of a light stream.
The lower the outside temperature, the more efficient the photocells and the solar battery as a whole work. Everything is simple here. But with the calculation of the load, the situation is more complicated. It should be selected based on the current generated by the panel. But its value varies depending on weather factors.
Heliopanels are manufactured with an output voltage multiple of 12 V - if 24 V is required for the battery, then two panels will have to be connected to it in parallel
It is problematic to constantly monitor the parameters of the solar battery and manually adjust its operation. To do this, it is better to use a control controller, which automatically adjusts the settings of the solar panel itself in order to achieve maximum performance and optimal operating modes from it.
The ideal angle of incidence of the sun's rays on the solar cell is straight. However, when the deviation is within 30 degrees from the perpendicular, the efficiency of the panel falls only around 5%. But with a further increase in this angle, an increasing proportion of solar radiation will be reflected, thereby reducing the efficiency of the solar cells.
If the battery is required to give maximum energy in the summer, then it should be oriented perpendicular to the average position of the Sun, which it occupies on the days of the equinox in spring and autumn.
For the Moscow region, it is approximately 40–45 degrees to the horizon. If the maximum is needed in winter, then the panel should be placed in a more vertical position.
And one more thing - dust and dirt greatly reduce the performance of solar cells. Photons through such a "dirty" barrier simply do not reach them, which means there is nothing to convert into electricity. Panels must be washed regularly or placed so that dust is washed off by the rain on their own.
Some solar cells have built-in lenses to concentrate radiation on solar cells. In clear weather, this leads to increased efficiency. However, with heavy cloud cover, these lenses only do harm.
If a conventional panel in this situation continues to generate current, albeit in smaller volumes, the lens model will stop working almost completely.
Ideally, the sun from a solar cell battery should be illuminated evenly. If one of its sections turns out to be darkened, then the unlit PEC turn into a parasitic load. They not only in this situation do not generate energy, but also take it from the working elements.
The panels must be installed so that there are no trees, buildings or other obstacles in the path of the sun's rays.
Power scheme of the house from the sun
The solar power system includes:
- Solar panels.
- Controller.
- Batteries
- Inverter (transformer).
The controller in this circuit protects both solar panels and batteries. On the one hand, it prevents reverse currents from flowing at night and in cloudy weather, and on the other, it protects batteries from excessive charge / discharge.
Batteries for solar panels should be selected the same in age and capacity, otherwise charging / discharging will occur unevenly, which will lead to a sharp decrease in their service life
To transform a direct current of 12, 24 or 48 Volts into alternating 220-volts, an inverter is needed.It is not recommended to use car batteries in such a scheme because of their inability to withstand frequent overcharges. It is best to spend money and purchase special helium AGM or jellied OPzS batteries.
The principles of operation and the connection diagram of solar panels are not too complicated to understand. And with the video materials collected by us below, it will be even easier to understand all the intricacies of the functioning and installation of solar panels.
It is accessible and understandable how the photovoltaic solar battery works, in all details:
How solar panels are arranged, see the following video:
DIY assembly of a solar panel from photocells:
Each element in the system of solar power supply of the cottage must be selected correctly. Inevitable power losses occur on batteries, transformers and the controller. And they must be reduced to a minimum, otherwise the sufficiently low efficiency of solar panels will be reduced to zero in general.
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