Solar energy is converted into electrical energy using PV materials and equipment. A cell is a single photovoltaic (PV) device. A single photovoltaic cell is typically a tiny device, with an average power output of 1 to 2 watts. These cells are frequently thinner than four human hairs and constructed of various semiconductor materials. Cells are sandwiched between protective materials in a combination of glass and/or plastics in order to endure the outdoors for a long time.
PV cells are chained together to create bigger units known as modules or panels, which increase their power output. You can use modules individually or link several of them to create arrays. The electrical grid is then linked to one or more arrays as part of a comprehensive PV system.
A PV system’s modules and arrays are merely one component. In addition to the components that convert the direct-current (DC) electricity generated by modules into the alternating-current (AC) electricity used to power all of the appliances in your home, systems also contain mounting structures that direct panels toward the sun.
What is a photovoltaic (PV) cell?
A photovoltaic (PV) cell, also known as a solar cell, can either reflect, absorb, or pass through light that strikes it. The semiconductor material that makes up the PV cell can conduct electricity more effectively than an insulator but not as effectively as a good conductor like a metal. In PV cells, a variety of semiconductor materials are employed.
When a semiconductor is exposed to light, it absorbs the light’s energy and transfers to the semiconductor’s negatively charged electrons. The additional energy enables the electrons to conduct an electrical current through the material. This current can be used to power your home and the rest of the electric grid by extracting it through conductive metal contacts, which are the grid-like lines on solar cells.
The basic materail of the semiconductor: SILICON
With silicon accounting for over 95% of the modules supplied today, silicon is by far the most prevalent semiconductor material in solar cells. The building blocks of crystalline silicon cells are silicon atoms interconnected to create a crystal lattice. This lattice offers a well-organized structure that improves the efficiency of turning light into electricity.
The semiconductor used in about 95% of solar panels now on the market is either monocrystalline silicon or polycrystalline silicon. Polycrystalline silicon is made up of many different crystal structures, whereas monocrystalline silicon wafers only contain one crystal structure. Although polycrystalline cells are less expensive to produce, monocrystalline panels are more efficient due to the greater free movement of the electrons throughout the electricity generation process.
The structure of semiconductor
P-type and n-type silicon are two different types of semiconductors that are used to make solar cells. Atoms with one fewer electron in their outer energy level than silicon, like boron or gallium, are added to create p-type silicon. An electron vacancy, sometimes known as a “hole,” is generated in boron because it has one fewer electron than is necessary to make the bonds with the neighboring silicon atoms.
By adding elements, like phosphorus, that have one extra electron in their outer level than silicon, the n-type silicon is created. The outer energy level of phosphorus contains five electrons, not four. It forms bonds with the silicon atoms next to it, however the bonds do not involve one electron. It can instead move around freely inside the silicon framework.
When sunlight strikes a solar cell, silicon’s electrons are evacuated, which causes “holes” to form—the voids the outgoing electrons left behind. The electric field will transport holes to the p-type layer and electrons to the n-type layer if this occurs. Electrons will move from the n-type layer to the p-type layer by crossing the depletion zone and then go through the external wire back of the n-type layer, causing an electrical flow, if the n-type and p-type layers connect by a metallic wire.
Limitation of silicon semiconductor
Due to the amount of sunlight the silicon semiconductor can absorb above the bandgap, the greatest theoretical efficiency level for a silicon solar cell is around 32%. The most effective commercial panels have efficiencies of about 18% to 22%, but scientists are looking into ways to increase efficiency and energy yield while lowering production costs.
Currently, silicon-based solar cells offer a mix of high efficiency, low cost, and long lifespan. Modules should last for at least 25 years and continue to generate more than 80% of their initial power after that.