Photovoltaics is a form of renewable energy that is obtained from solar radiation and converted into electricity through the use of photovoltaic cells. These cells, generally made of semiconductor materials such as silicon, capture photons of sunlight and generate electrical current.
The electrical generation process of a photovoltaic system begins with solar panels , which consist of multiple photovoltaic cells connected in series or parallel. When sunlight hits the cells, the electrons in the semiconductor material become excited and move, creating a continuous electrical current.
This current is collected and sent through wires to an inverter, which converts direct current into alternating current , which is the form of electricity used in homes and industry.
Parts and operation of a photovoltaic installation
A photovoltaic system consists of several components that work together to convert solar radiation into usable electricity.
The following describes how a basic photovoltaic solar energy system works:
Solar panels
Solar panels, also known as photovoltaic panels, are made up of photovoltaic cells that contain semiconductor materials, usually silicon. When photons of sunlight hit the cells, they excite the electrons in the semiconductor material and generate a direct electrical current.
Wiring and connections
Solar panels are connected in series or parallel to increase current or voltage as needed. Special electrical cables and connectors are used to interconnect the panels and create a solar array.
Inverter
The electrical current generated by solar panels is direct current (DC), but most devices and the electrical grid use alternating current (AC). Therefore, an inverter is used to convert direct current to alternating current. The inverter also controls and monitors system performance.
Bi-directional meter and grid connection system (if applicable)
In some photovoltaic systems, especially those connected to the electrical grid, a bidirectional meter is used to measure the amount of electricity generated and the amount of electricity consumed. If the system is connected to the electrical grid, excess electricity generated can be sent to the grid, and the meter records this additional production.
Batteries (optional)
Some solar installations include batteries to store excess electricity generated during the day and use it at night or during times of low solar radiation.
Batteries allow for energy self-sufficiency and the use of generated electricity even when sunlight is not available.
Advantages of photovoltaic energy
Photovoltaic systems offer several advantages compared to other energy sources. Here are some of the main advantages of this technology:
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Renewable and sustainable energy: Photovoltaic energy is based on solar radiation, an inexhaustible source of energy. Unlike fossil fuels, whose availability is limited and contribute to the depletion of natural resources, solar energy is a long-term sustainable option.
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Zero emissions and environmentally friendly: During the generation of electricity using solar panels, no greenhouse gas emissions or pollutants are released into the environment. This contributes to reducing the carbon footprint and mitigating climate change.
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Long-term cost savings: Once installed, a photovoltaic system can generate electricity for free from the sun. This makes it possible to reduce or even eliminate dependence on the conventional electrical grid and reduce long-term energy costs.
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Energy independence: the installation of solar panels allows users to generate their own electricity. This provides energy independence and reduces vulnerability to potential power outages.
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Wide applicability and scalability: Photovoltaic systems can be adapted to different needs and scales, from residential installations to large-scale projects.
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Low maintenance: Solar panels require minimal maintenance. Generally, it is only necessary to clean them periodically to ensure that solar radiation falls efficiently.
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Distributed generation: Photovoltaic systems can be installed in areas close to the point of consumption, which reduces electricity transmission and distribution losses, optimizes efficiency and contributes to the stability of the electrical grid.
Countries with the highest production of photovoltaic energy
The percentage of electrical energy generated by solar photovoltaic energy in the world has experienced significant growth in recent years. According to data from the International Renewable Energy Agency (IRENA), at the end of 2020, the installed capacity of solar photovoltaic energy worldwide reached 773 gigawatts (GW).
According to the International Energy Agency (IEA) Renewables 2021 report, in 2020, solar photovoltaics was responsible for around 3% of global electricity generation in the world.
Below is a table with some of the main countries in terms of photovoltaic energy generation in 2022.
|
Country |
Installed photovoltaic energy capacity (GW) |
Percentage of solar power compared to other energy sources |
|
China |
252 |
12.7% |
|
USA |
110 |
3.4% |
|
Japan |
67 |
9.7% |
|
Germany |
52 |
11.8% |
|
India |
Four. Five |
4.2% |
|
Australia |
twenty |
7.3% |
|
South Korea |
16 |
2.9% |
|
France |
12 |
2.7% |
|
Italy |
twenty |
8.6% |
|
Spain |
10 |
7.3% |
Efficiency of photovoltaic panels
Currently, the best conversion rate of sunlight into electricity is around 21.5%.
Depending on the construction, photovoltaic panels can produce electricity from a specific range of light frequencies. Anyway, in general it cannot cover the entire solar range. Specifically, photoelectric cells cannot convert ultraviolet , infrared and low or diffuse light into electricity.
One way to increase the efficiency of solar panels would be to illuminate them with monochromatic light, much higher efficiencies could be obtained.
Therefore, another design concept is to split the light into different wavelengths. Once separated, direct them towards different cells tuned to these ranges. An installation of this type is capable of increasing electrical efficiency by 50%.
Examples of uses and applications
The purpose of photovoltaic systems is the production of electricity that can be used in multiple applications. Here are some examples:
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Large-scale electrical energy generation. There are large power plants connected directly to the electrical grid that can generate hundreds of megawatts. However, these solar farms are built using solar concentrators and function as a thermal power plant.
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Systems integrated into roofs and buildings: These systems can be for electrical self-consumption but can also be connected to the public grid.
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Rural electrification. This type of solar application is used in rural villages where power lines are very far from the population.
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Street and highway lighting.
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Independent systems to power small devices such as calculators, solar mobile chargers, etc.
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In transportation: some electric vehicles have integrated solar systems to drive an electric motor and obtain driving power.
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Communications and signaling towers that use electrical devices that do not consume large amounts of electrical energy and that are difficult to connect to the electrical distribution network.
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Use in spacecraft and space stations since available energy sources in space are scarce.
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Systems for pumping water.
Types of photovoltaic installations
Photovoltaic installations are divided into two main categories according to their relationship with the electrical grid:
Systems connected to the public electrical grid
These photovoltaic systems are connected to the public electrical grid. In this approach, solar panels generate electricity when sunlight is available. If electricity production exceeds local demand at that time, the excess is injected into the electrical grid. In exchange, the system owner can receive credits or compensation for the electricity generated, often called "net metering."
This approach is common in urban and commercial areas and can include large photovoltaic plants or solar parks that generate electricity on a large scale.
Off-grid systems
Off-grid systems are independent of the public electrical grid and are used for self-consumption in places that do not have access to the electrical grid or in specific applications. These systems generate electricity from solar energy and store it in batteries for later use.
They are used in isolated homes, remote weather stations, road lighting in rural areas or remote locations, and in situations where it is not possible or cost-effective to connect to the conventional electrical grid.