Solar panels generate electricity from solar radiation. They are an essential element in a PV system facility.
Photovoltaic solar panels can generate electrical energy for both domestic and commercial uses. Typically, industrial solar panel facilities are connected to the power grid, and all electricity generated is supplied to the grid. Domestic solar power systems can be autonomous or connected, and it helps save money on the electricity bill.
The solar energy source is a renewable energy that reduces fossil fuel dependency.
Photovoltaic panels are made up of a set of interconnected photovoltaic cells. Each cell supplies DC electricity that an inverter will transform into AC electricity at the correct voltage.
How Do Photovoltaic Panels Generate Electricity?
The solar cells that make up a solar panel are made of semiconductor materials. Solar radiation is a compound of photons traveling at the speed's light.
When the photons that make up the light collide with the atoms of this material, they cause the displacement of an electron, which is what is called the photovoltaic effect. As a result, the sum of moving electrons generates an electric current in the form of a direct current (DC).
A solar cell can only generate an electrical voltage of a few tenths of a volt (+/- 0.5 V) and a maximum power of 1 or 2 Watts. Therefore, connecting several cells in series (which behave like small current generators) is necessary to get an acceptable voltage in the solar panel. Finally, we can link several solar panels to build a solar array to achieve the expected power.
What Technology Is Used in Solar Panels?
Silicon is the most widely used material for the construction of photovoltaic panels. Silicon is made into wafers that are later bonded together to form photovoltaic cells.
The most common types of photovoltaic cell construction are:
Monocrystalline silicon: this kind of silicon solar cell has 18-21% efficiency. They tend to be expensive and are also present. They are cut with cylindrical ingots; it is challenging to cover extended surfaces with them without wasting material or space.
Polycrystalline silicon: cheaper cells but less efficient (15-17%), whose advantage lies in the ease of cutting them into shapes suitable for joining in modules.
Amorphous silicon deposited by vapor phase: photovoltaic cells have low efficiency (8%) but are much cheaper to produce. Amorphous silicon (Si-a) has an important band of crystalline silicon (Si-c).
CIS: cells are based on chalcogenide layers (e.g. Cu (InxGa1-x) (SexS1-x) 2). They have an efficiency of up to 15%, but their cost is still too high.
Photoelectrochemical cells: First built in 1991, these photovoltaic cells were initially designed to mimic the process of photosynthesis.
Hybrid photovoltaic cell: combines the advantages of organic semiconductors and various types of inorganic semiconductors.
Concentrated photovoltaic cell: the use of this cell in a PV panel combines the technologies mentioned above with solar concentration lenses that significantly increase efficiency. They represent the promising new generation of panels still under development.
How Can the Performance of Photovoltaic Panels Be Improved?
There are many options to increase the yields of this power source. Among them, the following techniques are the most popular:
1. Solar Trackers
Solar trackers work using a motor generally associated with a computer. The system adjusts the solar panel's orientation depending on the date and time of day. These systems are naturally more complex and involve more significant expense and higher maintenance.
2. Light Diffraction
The light diffraction phenomenon makes it possible to obtain photovoltaic panels with a higher transparency index than the apparent one since the shadow cast by each cell inside the building is less than the surface it occupies.
It implies that the solar panel is significantly more opaque from the outside than from the inside.
It is also possible to obtain greater transparency if the distance between the cells is increased within the same PV panel.
How Are Solar Panels Made?
The photovoltaic panel is designed to withstand the conditions that occur outdoors and to be able to form part of the "skin" of the building. If you want to buy solar panels, most providers will assure you that their useful life is about 25 years if you're going to buy solar panels.
The cells are encapsulated in a resin and placed between two sheets to form solar panels. The outer layer is made of glass, and the back can be made of opaque plastic or glass if you want to do a semi-transparent panel.
Crystalline silicon and gallium arsenide are typical material choices for solar cells. Gallium arsenide crystals are created especially for photovoltaic uses, but silicon crystals are also produced for consumption by the microelectronics industry.
When exposed to 1 AU direct light, a 6-centimeter diameter silicon cell can produce a current of 0.5 amps at 0.5 volts. Gallium arsenide is more efficient.
The glass is cut into small disks and polished to eliminate the danger of cutting. Dopants are inserted into the disks. Metallic controllers are deposited on each surface: a connector on the surface facing the sun and a connector on the opposite side. PV panels are built with these cells cut into appropriate shapes, protected against radiation, and damaged by applying a layer of glass and cemented onto a substrate.
Electrical connections are made in parallel series to determine the total output voltage.
The protective layer must not be a thermal conductor. Since cell heating reduces operating efficiency, it is desirable to reduce this heat.