Multilayered solar panels.
Classical solar panels occupy large areas that are not always available. The company Green Energy solves this problem by inventing the multilayered solar panel more and more people prefer alternative energy sources aiming to be independent in their power supply. The owners of private houses and cottages choose the source of electricity with solar panels among the many alternative sources of supply, the correct name of which is photovoltaic panels.
Equipment for the conversion of solar energy is quite expensive, but free electric energy will quickly cover expensed finances. Also solar panel is an environmentally friendly source of energy that doesn"t produce any air emissions. Prices for photovoltaic panels have decreased drastically and they keep on decreasing due to the great prospects of development of science in the industry. Standard structure of power plant based on solar panels:
- Solar battery which produces direct current
- Rechargeable battery pack
- Inverter with charge control
- Commuting equipment
Solar panels consist of many photovoltaic converters (PVC) which convert solar energy directly into electricity. The direct or one-stage transition of solar energy into electrical energy is the most economical. The first photovoltaic cells were designed by the Bell Labs company in 1950 for the space industry.
The process of energy transfer in the photovoltaic converter from one state to another is based on the photovoltaic effect that arises in inhomogeneous semiconductor structures when exposed to sunlight. The efficiency of conversion depends on the optical properties of the transducer, electrophysical characteristics of semiconductor cells. The most important property of a semiconductor is its photoconductivity determined by the internal photo effect phenomena in semiconductors during their exposure to light.
The principle of PVC operation can be explained on the example of converters with a p-n junction that is the most common in bioenergetics. P-n junction or electron-hole junction is an area of a semiconductor which holds the spatial variation of conductivity type from electron n to hole p. Combined bands with an uncompensated volumetric positive charge in n-layer and volumetric negative charge in p-layer are formed at the border of n and p-layers in response to leakage of charges during solar radiation of module.
Therefore, the barrier (potential difference) occurs at this transition. Due to this very feature of the p-n junction, we can explain the fact of photoelectromotive force occurrence when exposed to sunlight. The most of the solar cells are made of valuable silicon. This fact determines the initial high cost of electricity which is obtained when using solar panels.
Photovoltaic converters can be divided into the ones made of single-crystal silicon and the ones made of silicon polycrystalline that are identifiable by their production technology. The former has efficiency up to 17.5% while the latter one up to 15%. The most important technical parameter of the solar cell, which has a major impact on the efficiency of the entire system, is its useful power. It is determined by voltage and output current. These parameters depend on the intensity of the sunlight falling on the panel as well as the solar panel design in which the Green Energy company has made a technological breakthrough. Further, you will learn about this in more detail.
Electromotive force (EMF) of the individual solar panels doesnÔÇŁt depend on their size and it decreases with battery heated by the sun, by about 0.4% per 1 g. C. 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 solar cells. The charging current and output power in cloudy weather decreases dramatically.
If the battery illuminated by the sun is closed to any load with resistance RL, the electric current I appears in the circuit, the value of which is determined by the quality of the photoelectric converter, light intensity, and load resistance. Power PL, which is released in the load is determined by the product of the ILUL = UL where UL is voltage at the terminals of the battery. The top power is produced in the load at its optimum resistance Ropt which corresponds to the highest coefficient of performance (COP) of conversion of the light energy into electrical energy. Each converter has its own value Ropt that depends on the quality, work surface size, and luminance degree.
Solar cells inside the battery are connected in series and in parallel to increase the output parameters (current, voltage and power). Series connection increases output voltage and parallel connection increases output current. These two ways of connection are combined in order to extend both current and voltage. In this way, the connection failure of one of the solar cells does not result in failure of the entire circuit, which also increases the reliability of the entire battery.
Consequently, a solar panel consists of parallel-series connected solar cells. The value of the maximum possible current given by the battery is directly proportional to the number of parallel-connected solar cells and COP is directly proportional to the number of series-connected ones. The battery with required parameters is assembled by combining these types of connection.
Solar cells of the battery are shunted with diodes. Usually, there are 4 of them, one for each ┬╝ of the battery. Diodes protect from failure the parts of the battery which for some reason turned out to be blacked out, i.e. if at any point of time they donÔÇŁt get the sunlight. At this, the battery temporarily generates 25% less output than under normal conditions of lighting the entire panel surface. In the absence of these diodes, solar cells will overheat and fail, as they turn into the current consumers for the time of blackout (batteries discharge through the solar cells. With the use of diodes, they are shunted and the current doesnÔÇŁt go through them. The resulting electrical energy is stored in batteries and then given to the load. Batteries are the chemical current sources. The battery charge arises when it is accompanied by the potential that is greater than the battery voltage. The number of series and parallel connection of solar cells must be such that the operating voltage supplied to the battery taking into account the voltage drop in the charging circuit is slightly greater than the battery voltage, and the load current of the battery provides required amount of charging current. For example, to charge a lead storage battery 12B a solar cell consisting of 36 elements is needed.
In weak sunlight battery charge decreases and the battery gives electrical energy to the receiver, i.e. the batteries run continuously in the discharge and charge mode. This process is controlled by a special controller. A constant voltage or constant current charge is required in the cyclic charge. In strong light the battery charges quickly to 90% of its nominal capacity, followed by a slower rate of charge to full capacity. Switching to a lower charge rate is made by the controller charger. The usage of special batteries such as gel and lead batteries made by AGM-technology is the most effective. These batteries donÔÇŁt need special installment conditions or maintenance. Rated service life for such batteries is 10 - 12 years at a 20% depth of discharge. Batteries should never be discharged below this value; otherwise, their service life reduces dramatically.
The battery is connected to the solar panel through the controller, which controls its charge. The solar cell is connected to a resistor which absorbs the excess power when charging the battery to full capacity.
In order to convert the DC voltage from the battery into an AC voltage, it is possible to use special devices or inverters. Without the usage of invertors, solar batteries can charge the power-consuming units running at a constant voltage, including various portable equipment, energy-saving light sources, such as LED lamps.
So what is the advantage of the multilayered solar panels developed by the Green Energy company over the classical solar panels? As you understood from our article, quite large areas are needed for power supply of houses. What to do if these areas are not enough to create the necessary power? Here are the parameters of the standard solar panel:
So, what do we see? With rather a large area of the panel, its thickness is only 35mm. This is the characteristic of the single-layer solar panels. The Green Energy company has designed a multi-layer solar cell, which with the same area, has a thickness of three times as much. This is necessary to place additional elements inside the battery. Light comes to the internal elements due to the clear glass located on the perimeter as well as a system of mirrors and optical fibers.
As we can see, to provide the power of 800 W at a voltage of 230V, it is enough to connect two multi-layer solar cells in series. The usage of multilayered solar cells developed by Green Energy can significantly reduce the occupied area. The only disadvantage of the multilayered panels is their price. But Green Energy doesnÔÇŁt stay still trying to reduce the manufacturing costs of solar cells.