Photovoltaic energy 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 from sunlight and generate electrical current.
The electrical generation process of a photovoltaic system begins with the solar panels, which consist of multiple photovoltaic cells connected in series or parallel. When sunlight hits the cells, electrons in the semiconductor material become excited and move, creating a continuous electrical current.
This current is collected and sent through cables 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 System
A photovoltaic system consists of several components that work together to convert solar radiation into usable electricity. The following describes how a basic photovoltaic system works:
Solar Panels
Solar panels, also known as photovoltaic modules, are made up of photovoltaic cells that contain semiconductor materials, usually silicon. When photons of sunlight strike cells, they excite electrons in the semiconductor material and generate a continuous electrical current.
Wiring and Connections
Solar panels are connected in series or parallel to increase current or voltage as needed. Special cables and connectors are used to interconnect the panels and create a solar array.
Investor
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 the performance of the system.
Two-way Meter and Network 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, the excess electricity generated can be sent to the grid, and the meter registers this additional production.
Batteries (optional)
Some photovoltaic systems include batteries to store excess electricity generated during the day and use it at night or at times of low solar radiation.
Batteries allow energy self-sufficiency and the use of generated electricity even when sunlight is not available.
Advantages of Photovoltaic Systems
Photovoltaic systems offer several advantages compared to other energy sources. Here are some of the main advantages of this technology:
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 sustainable option in the long term.
Zero emissions and respectful with the environment: During the generation of electricity through solar panels, no greenhouse gas emissions or pollutants are released into the environment. This contributes to reducing the carbon footprint and mitigating climate change.
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 dependency on the conventional electrical grid and lower energy costs in the long run.
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.
Wide Applicability and Scalability: PV systems can be adapted to different needs and scales, from residential installations to large-scale projects.
Low need for maintenance: Solar panels require minimal maintenance. Generally, it is only necessary to clean them periodically to ensure that solar radiation hits efficiently.
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 network.
Countries with the Highest Production of Photovoltaic Energy
The percentage of electrical energy generated by photovoltaic solar 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 photovoltaic solar energy worldwide reached 773 gigawatts (GW).
According to the International Energy Agency (IEA) Renewables 2021 report, in 2020, solar PV 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 capacity of photovoltaic energy (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 | 45 | 4.2% |
Australia | 20 | 7.3% |
south korea | 16 | 2.9% |
France | 12 | 2.7% |
Italy | 20 | 8.6% |
spain | 10 | 7.3% |
Efficiency of Photovoltaic Panels
Currently, the best conversion rate of sunlight to photovoltaics is around 21.5%.
Depending on the construction, photovoltaic modules can produce electricity from a specific range of light frequencies. In general, however, it cannot cover the entire solar range. Specifically, photoelectric cells cannot convert ultraviolet , infrared, and low light 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 light into different wavelengths. Once separated, direct them towards different cells tuned in these ranges. A photovoltaic system of this type is capable of raising electrical efficiency by 50%.
Examples of Uses of Photovoltaic Energy
The purpose of photovoltaic systems is the production of electricity that can be used in multiple applications. Here are some examples:
Large-scale electricity 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 station.
Systems integrated into roofs and buildings: These systems can be for electrical self-consumption but they can also be connected to the public network.
Rural electrification. This type of solar application is used in rural villages where power lines are very far from the population.
Street and highway lighting.
Independent systems to power small devices such as calculators, solar mobile chargers, etc.
In transportation: Some electric vehicles have integrated solar systems to drive an electric motor for motive power.
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.
Use in spacecraft and space stations as available power sources in space are scarce.
Systems for pumping water.
Types of Photovoltaic Systems
Photovoltaic systems can be of two different types:
Photovoltaic systems connected to the public electricity grid. Within the photovoltaic systems connected to the grid there are large photovoltaic plants or solar parks.
Off-grid photovoltaic systems. These types of systems are used for self-consumption and can be used in isolated houses, road lighting or other remote places.
