Solar energy how it works? Photovoltaic power generation is a power generation method that directly converts the light energy of the sun into electricity using a device called a “solar cell.”
The amount of solar energy reaching the earth is about 1 kW per 1 m2 . If we could convert 100% of the solar energy that hits the entire earth, it would be huge enough to cover the world’s annual energy consumption in just one hour, and there is no fear of exhaustion.
Currently, most energy resources such as oil and coal , but if these fossil fuels are used, they will eventually disappear. Photovoltaic power generation, which utilizes the inexhaustible energy of the sun’s rays, is one of the leading solutions to the problem of energy resources, which is getting worse year by year.
Another major feature is that it is clean. Carbon dioxide (CO 2 ), which is a cause of global warming during power generation, is not emitted at all during power generation.
Solar power generation is easy to secure energy sources and is kind to the earth. The United States is also a country with top-class solar power generation technology in the world, and it is expected that the amount of solar power generation will increase further.
How much can you contribute to the environment?
By installing a solar power generation system, it is possible to reduce CO2 emissions from thermal power plants and save the amount of crude oil consumed there.
For example, if you install a 10kW solar power generation system, you can expect to generate approximately 10,000 kWh of electricity per year. This represents a reduction of crude oil consumption of approximately 2,270 liters per year and a reduction of CO 2 emissions of 5.415 t-CO 2 .
Features of solar power generation
The three main features of photovoltaic power generation, when compared to other power generation systems, are as follows.
Feature 1: Clean and not exhausted
The greatest feature of photovoltaic power generation is that it has an inexhaustible and clean source of energy. Unlike thermal power generation that burns oil to generate electricity, it does not generate atmospheric pollutants such as CO 2 (carbon dioxide), SO X (sulfur oxides), and NO X (nitrogen oxides) during power generation . ..
By the way, if the annual power generation of the 1kW system is 1,000kWh, the CO 2 reduction effect of the crystalline silicon solar cell is 541.5kg per 1kW system per year. The amount of crude oil reduction is 227 liters per 1kW system per year (Source: Photovoltaic Power Generation Association “Display Guidelines”).
Feature 2: Can be installed anywhere
Photovoltaic power generation has almost the same power generation efficiency regardless of the scale of the installed system. Since the scale can be freely determined according to the size of the installation site, it is possible to install a system that suits each facility, from general households to large-scale facilities. It does not generate noise or emissions during power generation, so it can be installed anywhere as long as the amount of solar radiation can be secured. In addition to installation on roofs and rooftops, in recent years the number of installations on the walls of buildings has increased.
Feature 3: Easy maintenance
The solar power system is structurally simple and therefore easier to maintain than other power generation systems. The service life of the system is relatively long, and the service life of solar cell modules used for photovoltaic power generation is now considered to be 20 years or more (depending on various conditions such as the installation location).
Solar energy how it works
A solar power generation system for houses converts the DC power generated by the solar cells by receiving the light energy of the sun into the same AC power as the power company using a power conditioner and supplies electricity to various home appliances in the home. To do. In a general grid-connected solar power generation system, it is connected to the distribution line of the electric power company, so if the generated power exceeds the power consumption, it will be transmitted to the electric power company (reverse power flow) to buy electricity. You can get it. On the other hand, when it is not enough to generate electricity, such as on a cloudy or rainy day, or at night, electricity from the power company is used as usual. It should be noted that this kind of electricity exchange is automatic, so daily operations are not required
A device that directly converts the light energy of the sun into electricity.
A device that collects the DC wiring from the solar cell into one and sends it to the power conditioner.
A device for converting DC power generated by solar cells into AC power.
A device that divides electricity into the house wiring.
A meter that measures the amount of electricity sold or purchased by a power company. You need two electricity meters, one for selling and one for buying.
A method of operating a private power generation facility by connecting it to the distribution line of a power company.
Electricity flows from the power generation equipment for private use such as grid-connected photovoltaic power generation to the distribution line (commercial grid) of the electric power company.
What is a solar cell and How solar cells work
At the heart of solar power generation systems are solar cells.A solar cell is an energy conversion element that absorbs the light energy of the sun and converts it directly into electricity. It is made of a semiconductor such as silicon. When this semiconductor is exposed to light, it generates electricity in proportion to the intensity of solar radiation.
Although it has the name “battery”, it cannot store electricity.By the way, photovoltaic power generation is called Photovoltaic (PV) power generation in English.
The most widely used solar cells today are silicon solar cells. This solar cell has a structure in which two types of semiconductors (p-type and n-type) with different electrical properties are stacked.
When the sunlight hits the solar cell, electrons (-) and holes (+) are generated, and the holes are attracted to the p-type semiconductor and the electrons are attracted to the n-type semiconductor. For this reason, if a load such as a light bulb or a motor is connected to the electrodes on the front and back sides, the current will flow out.
What is conversion efficiency?
The conversion efficiency is a numerical value that represents the ratio of the energy of light incident on the solar cell converted to electrical energy and is calculated by the following calculation.
In other words, it represents the percentage of 1 kW of light energy that can be converted into electrical energy per 1 m2 of the solar cell module.
(Example) With a conversion efficiency of 10%, there is 1 kW / m2 of energy (standard for solar radiation intensity) on the ground in fine weather, and when this energy is applied to a 1 m 2 solar cell, It means that the generated power will be 100 W.
Types of solar cells
■ Silicon type ■ Compound-based *
Crystal system: Single crystal silicon
Polycrystalline silicon III-V family
Thin-film system: Amorphous silicon / thin-film Polycrystalline silicon (CIS, CIGS, CdTe, organic thin-film, dye sensitization, etc. Compound-based)
* Including organic compounds and dye sensitization.
Solar cells, modules, arrays
There are “cells”, “modules”, and “arrays” in the structural units such as solar cells.
The basic unit of a solar cell, the solar cell element itself is called a cell.
The required number of cells are arranged and protected by resin or tempered glass so that they can be used outdoors and packaged. This module is also called a solar panel.
An array consists of multiple modules (panels) arranged side by side and connected.
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