A photovoltaic plant produces electricity by absorbing sunlight. The elements that make it up consist of solar cells, a metal frame, a glass envelope and cables. It is usually installed on a roof or a large outdoor space. Photovoltaic cells are made of silicon and collect electrons from sunlight and convert them into electrical current. These solutions are fully in line with the field of Smart Energy, which aims at optimizing energy efficiency.
Photovoltaic solar panels: main characteristics
Photovoltaic solar panels produce electricity by absorbing sunlight and converting it into electrical current. They are safe and do not produce any noise during their operation. They are made of silicon sheets and do not release toxins or fumes. Solar panels react to visible light and the stronger the light, the more energy they can produce.
The typical solar panel consists of a layer of silicon cells connected to a metal frame and a glass envelope. The glass envelope protects the solar cells and gives them durability. Photovoltaic solar panels are typically placed on rooftops or large outdoor areas to maximize their potential to generate electricity. Silicon cells are designed to absorb sunlight during the day and transform it into electrical current. This process is known as the photovoltaic effect.
In a photovoltaic cell, photons from the sun release electrons into the atoms. These electrons then circulate in a conductor. In a solar installation, many panels can be linked together to produce more electricity. The more panels there are, the higher the energy production.
The photovoltaic inverter transforms the direct current produced by the solar panels into alternating current
Inverters are devices that convert the direct current produced by solar panels into alternating current (AC). Inverters convert direct current from one form to another, and can either send excess energy back to the grid or mix solar and grid energy.
Solar panels produce electricity from sunlight, which strikes a photovoltaic cell. The light causes the electrons to move to a higher activity level, and these electrons escape from the solar panel. An inverter converts this current into alternating current, which can be used by modern household appliances and electronics.
A photovoltaic inverter converts DC energy from the panels into AC power using a voltage-controlled pulse width modulation (PWM) device. This process reduces the generation of low-order harmonics, which cause problems in electrical systems and wiring. It also limits the production of high frequency harmonics by filtering the output current.
Multi-junction devices convert more of the energy spectrum of light into electricity
Multi-junction devices are solar cells with more than one p-n junction, which allows them to convert more of the light spectrum into electricity. They are usually made of two or more semiconductor materials with different band gaps, and the devices use a top cell to capture high-energy photons, while the bottom cells absorb the rest of the photons. As a result, multi-junction solar cells have higher efficiencies than single-junction solar cells.
However, multi-function devices are not cheap to produce. They require semiconductor fabrication techniques such as metal-organic vapor phase epitaxy, which involves fabricating multi-junction solar cells on centimeter-sized chips. Currently, there are three main categories of photovoltaic cells:
- conventional monocrystalline silicon cells,
- multi-junction solar cells
- thin film solar cells.
The conductive metal plates on the sides of a photovoltaic plant collect electrons and transfer them to wires. To create electricity, a photovoltaic solar power plant uses special semiconductors, such as silicon, that absorb light. This light releases the electrons which are directed towards the wires. The photovoltaic cells are connected in arrays and form solar panels. These arrays can form a network or be attached to a single house.
The sides of the photovoltaic plant are usually made of dark conductive materials, called absorbers. These materials have a high absorption coefficient, which is the amount of photons absorbed per unit distance through the material. The acceptor is a hole that can accept a free electron. The side panels of a photovoltaic power plant are designed to collect large amounts of electricity.
Once a photovoltaic cell is built, sunlight hits the solar cell. This free electron hits the conductive metal plates, which then transfer it to the wires. Like any other source of electricity, electrons can flow through the wires.
Concentrated solar thermal systems (CSP) produce superheated steam at high pressure
Concentrated solar thermal power is a type of system that uses concentrated sunlight to produce electricity and steam at high pressure. These systems are most effective in areas where solar radiation is high but not too diffuse. They must also have access to a high voltage transmission network. Large-scale solar power projects depend on high-voltage transmission lines to carry electricity from solar power plants to end users. Unfortunately, the current transmission infrastructure in the Southwest is nearly saturated and new lines are urgently needed.
The most common and advanced CSP systems are:
- parabolic cylindrical furnaces,
- linear Fresnel systems,
- electric towers.
They are very efficient and can produce electricity from 10 to 200 MW. In addition to power generation, these systems can also provide heat for industrial applications such as :
enhanced oil recovery
Solar energy can be an excellent way to optimize the energy management of industrial buildings.
Advantages and disadvantages of a photovoltaic plant
A photovoltaic plant has several advantages and disadvantages. Among the disadvantages of solar panels is their dependence on sunlight. Indeed, the intensity of the sun varies throughout the day and the year. Therefore, solar panels cannot produce electricity at night. Clouds and snow can also affect the efficiency of solar panels. In this case, it may be necessary to add a battery storage system.
Another disadvantage is the installation conditions of the solar panels. For example, flat-roofed houses are not ideal for photovoltaic panels because they are difficult to slide. In addition, shaded roofs may not receive enough sunlight to produce energy. Finally, obstructions in the path of the sun can prevent these panels from producing electricity.
That being said, a photovoltaic plant can offer many advantages. We know that today, the world’s energy consumption is largely dependent on fossil resources. Their collection and use generate greenhouse gases and significant air pollution. We also know that these resources are limited and will soon reach a critical threshold. To face their depletion, they must be used in combination with renewable energies such as solar energy. The latter is a free, inexhaustible resource accessible to all. In spite of a consequent initial investment, a photovoltaic power plant pays for itself very well in the long term.
A photovoltaic plant can benefit companies, local authorities and farmers. Indeed, in a farm, agrivoltaics can for example mix with agriculture by using solar panels to protect crops. Communities can take advantage of the sun’s rays by installing a photovoltaic plant on the properties they administer. Finally, companies can use solar panels and use technologies like IoT to gain energy efficiency. You can find this in the definition of the smart grid.
Cost of producing solar energy
The cost of producing solar energy depends on the size and efficiency of the panels. The best panels are monocrystalline, which reflect the most light and convert it into electrical and thermal energy. Other types of solar panels are polycrystalline or thin film. The latter type is less expensive to produce but less effective. Prices can vary significantly from state to state due to differences in system size and rating trends. Some states also offer incentives to help solar consumers offset the cost of solar panels.
Solar panels can be expensive, but the initial demand for satellites has brought prices down, allowing more people to afford them. As the cost of solar panels has decreased, panels have been adopted for other uses, including homes and industrial or commercial buildings. This “virtuous cycle” continued as technology improved and economies of scale increased. Finally, solar power has become a general purpose energy source, with its cost decreasing by 20.2% for every doubling of solar power generation capacity.
Environmental impact of solar energy
When solar panels are used to generate electricity, they produce no emissions and have minimal impact on the environment for most of their life cycle. However, solar panels must be manufactured and recycled before they can be reused. This involves energy-intensive manufacturing processes that produce a significant environmental impact.
The installation of solar energy systems also requires a significant amount of land. However, some areas are more suitable for installation than others. Whether you install solar panels on existing structures or install them on new structures, the amount of land cleared can have a significant impact on local ecosystems. In addition, the construction of transmission lines and roads can fragment habitats and disturb local wildlife.
The reliability of a photovoltaic installation is a key element of PV systems. The reliability of a photovoltaic system depends on how the system is designed. The components are arranged in a certain way to meet the established performance levels. The reliability of a PV system can be compromised if a component or system fails.
Solar radiation and seasonal climate variations have a direct impact on the reliability of electricity. The higher the solar radiation, the more reliable the electricity production. However, this relationship is not linear.
For example, a slight decrease in solar radiation can result in a sharp decrease in the amount of energy produced. Conversely, a large variation in solar radiation during the winter can result in increased electricity reliability.