Solar panels are the fundamental components to generate electrical energy in a photovoltaic solar system. Solar power is a renewable energy that can be stored in batteries or supplied directly to the electrical grid.
The most crucial component of the solar panels is the photovoltaic (PV) cells responsible for producing electricity from solar radiation. The rest of the elements that are part of a solar panel protect and give firmness and functionality to the whole.
The structure of a solar panel is divided into different parts or components. Currently, the solar panel's parts are the following:
1. Front cover
The front cover is the part of the solar panel that has the function of protecting the solar panel from weather conditions and atmospheric agents. Again, tempered glass with low iron content is used since it offers good protection against impacts and is an excellent transmitter of solar radiation.
Although a flat cover is necessary to protect the photovoltaic cells, depending on the quality of the protective glass, it can lower the solar panel's performance.
2. Encapsulated Layers
The encapsulated layers are responsible for protecting the solar cells and their contacts. In addition, the materials used (EVA) provide excellent transmission of solar radiation and zero degradation against ultraviolet radiation.
EVA is a thermoplastic polymer of ethylene and vinyl acetate, which acts as a thermal and transparent insulator to allow the sun's rays to pass through to the PV cells. In addition, it provides cohesion to the panel as a whole by filling the existing volume between the front and rear covers, thus damping the vibrations and impacts that may occur.
The most critical problems presented by copolymers such as EVA are their excessive plasticity, excellent adherence to dust, which causes a decrease in transmissivity to solar radiation, and their short useful life, which usually conditions the useful life of the entire module.
3. Support frame
The support frame is the part that gives the mechanical strength. For example, the support frame of a solar panel allows its insertion in structures that will group modules.
The frame is usually made of aluminum, although it can also be made of other materials. The material must resist different climatic conditions and promote heat dissipation. The solar panel's increase in thermal energy reduces the photovoltaic effect's performance.
The support frame is attached to the structure that determines the tilt and orientation of the solar panel. On rooftop solar panels, you can consider installing the panels directly on the roof surface (if facing south), taking advantage of the roof's slope. However, it is better to use some structures on flat roofs to achieve optimal orientation and slope.
4. Rear guard
This part of the solar panel aims to protect against atmospheric agents, exerting an insurmountable barrier against humidity.
Typically, acrylic, Tedlar, or EVA materials are used. They are often white, which favors the panel's performance due to the reflection it produces in the cells.
5. Electrical connection box
The electrical currents generated by the PV cells are conducted to a junction box to be unified. This electric system component links the solar cell to the battery.
Two wires with a difference in electrical potential between them come out of the electrical connection box. The box is the place where there is continuity in the electrical circuit.
Some photovoltaic modules have a ground connection, which should be used in high-power installations.
6. Photovoltaic cells
Photovoltaic cells are the most critical part of the solar panel structure of a solar system. These are semiconductor devices capable of generating a DC electrical current from the impact of solar radiation.
Photoelectric cells appeared for the first time in the mid-nineteenth century thanks to the discovery of the photovoltaic effect by the physicist Alexandre Edmond Becquerel, who devoted his life to research into the solar spectrum, electrical energy, luminescence, etc.
This solar product works pretty simply: when the cells that make up the solar panels are exposed to solar radiation, the so-called PV effect occurs, which converts photons of sunlight into electrons. That is, it transforms solar radiation into electrical energy.
It occurs because the semiconductor material can absorb part of the incident photons on its surface.
A photon produces in the semiconductor material a "hole" in the valence shell of the silicon atom. It means an electron from the valence shell is released, becoming a free electron. Each of these electrons migrates to a part of the cell, generating an electrical current in the semiconductor that can travel through an external circuit and be released as electrical energy.
7. Solar panel stand
Within the components that make up a photovoltaic system, the structures of the photovoltaic panels are passive components that facilitate the installation of the solar PV modules. Solar mounting structures must constantly withstand outdoor weather conditions.
The solar panel mounting structure fixes its position and stays stable for years. They are vital since the inclination of the structure will be responsible for the solar module receiving adequate solar radiation.
8. Charge regulator
Its function is to manage the energy of the batteries optimally. In this way, it prevents the power system from overloading or over-discharging while at the same time extending the useful life of the accumulators.
It has a maximum current capacity in amps that guarantees an adequate charge while ensuring an optimal electrical supply.
9. Battery or accumulator
The battery storage is responsible for regulating the electrical energy that reaches it. It is energy storage so that it can be used later, whenever necessary. The battery is an elementary component to provide the installation with energy during days of low light or sunlight.
In this way, the objective of the accumulator can be summarized in three highlighted functions
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It stores energy for a specific time.
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It provides an immediate power output high enough to provide an adequate supply.
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Limits and fixes the working voltage of the system to avoid voltage drops throughout the installation.
10. Investor
The inverter converts the direct current from the batteries into the alternating or conventional current. Said current must be the same as the electrical network's (220 V with a frequency of 50 Hz).
Of course, once this energy system is in operation, it must adapt to the maximum power demand available in the equipment coupled to it. Hence, it is an element of high efficiency and safety, key in PV systems connected to the network and in those autonomous whose mission is to provide electricity to a home.