Solar panels are indispensable for harnessing sunlight and converting it into usable electricity. The photovoltaic effect describes how solar cells transform sunlight into electricity, which you can use to run various electrical devices. When light from the sun strikes solar cells, they gain energy and release it as a direct current (DC). An inverter transforms this direct current (DC) power into usable alternating (AC) power.
Solar power is becoming more popular since it is a reliable and sustainable energy source that doesn’t contribute to climate change or release harmful byproducts. However, solar panel science is even more intriguing. You can learn a lot about solar energy, from making solar cells to what goes into a solar power installation.
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Components of a Solar Panel System
Solar panels
A solar panel is a device that employs photovoltaic (PV) cells to generate electricity from direct sunlight. Panels made of solar cells are also known as PV modules or solar electric panels.
Inverter
Solar panels produce DC (direct current) electricity, while most buildings require AC (alternating current) power. An inverter is a device that changes direct current (DC) electricity into alternating current (AC) electricity, which you can use to run household appliances, lights, and other electrical equipment. Inverters change the voltage and may also have monitoring and control tools that let the user keep tabs on how well their solar panels are doing.
Batteries
Batteries can store the extra energy solar panels produce during low sunshine or at night. When solar panels cannot supply enough energy, you can use batteries to run electronics and appliances.
Charge Controller
A charge controller is an electronic component that manages energy transfer from solar panels to storage batteries. Some charge controllers may also have monitoring and management capabilities.
Types of Solar Cells
Crystalline Silicon Solar Cells
Crystalline silicon solar cells account for over 90% of the industry, making them the most widely used variety. The solar cells of these panels are made of pure crystalline silicon wafers, making them highly efficient in converting sunlight into power. Crystalline silicon solar panels come in a few different types, the most popular being monocrystalline and polycrystalline solar cells. Monocrystalline solar cells are more efficient than multi-crystalline ones but are more expensive because they require only a single, pure silicon crystal. Although cheaper, polycrystalline solar cells are less efficient than monocrystalline ones since they comprise several smaller silicon crystals.
Thin Film Solar Cells
Thin-film solar cells, or thin-film photovoltaics, are roughly one hundred times thinner than crystalline silicon cells produced from wafers that are only a fraction of a millimeter deep. Amorphous Silicon (a-Si) creates these thin-film solar panels and cells. The atoms in a-Si are organized in a random pattern instead of forming an ordered crystalline structure. CdTe, CIGS, and organic PV materials are other viable options for fabricating these films.
The most cost-effective method of making solar panels, these cells are made by stacking photovoltaics to create a module. The cells can be laminated onto glass, metal, and polymers for various applications. Despite its adaptability, their efficiency is lower than that of standard crystalline silicon cells. These thin film cells have an efficiency of only about 7%, compared to 20% for crystalline silicon cells. The most performing CIGS cells only operate at a mere 13% efficiency.
Process of Conversion of Solar Energy to Electrical Energy in solar cells
Solar energy from sunlight is absorbed by the photovoltaic cells in a solar panel. Silicon atoms absorb the photons causing the atom’s electrons to be dislodged. After that, the released electrons can circulate freely throughout the solar cell.
The freed electrons then flow toward the solar cell’s p-n junction. The electrons create an electric field at the p-n junction, which can collect the energy emitted from the sun and convert it into electricity. The electricity produced by the solar cell can be used to power various electrical appliances.
At the p-n junction, electrons and holes are produced after establishing the electric field. Electrons move in the opposite direction of the holes, that is, the negatively charged side of the solar panel. The movement of electrons and holes across a solar panel produces a voltage differential across the panel. The voltage difference is necessary for generating power from the solar panel.
Electrons migrate through the metal contacts at both ends of the solar panel due to the voltage difference between the top and bottom of the panel. Metal contacts act as a conduit for electricity, enabling electrons to go through the solar panel. As a result, electrical energy is produced.
The Making of Solar Panels
The process of making solar cells involves the following seven steps:
Purify the Silicon
A carbon arc is used in an electric arc furnace to release the oxygen trapped in silicon dioxide. The remaining substances after the purification process are carbon dioxide and molten Silicon. The resulting Silicon has an impurity level of only 1%. The floating zone technique involves periodically passing rods of 99% pure silicon across a heated zone in the same direction. The contaminated portion of the rod can be readily cut off and thrown away by employing this technique repeatedly.
Creating Single Crystal Silicon
Single-crystal Silicon is created via the Czochralski Method, which involves dipping a seed silicon crystal into molten polycrystalline Silicon. A cylindrical ingot or boule is made by rotating the seed crystal extracted from the molten polycrystalline material.
Cut The Silicon Wafers
The second-stage boule is cut into silicon wafers with a circular saw. When Silicon is etched using a diamond saw, uniform slices are produced, which can then be further shaped into squares or hexagons for more effective assembly on the surface of a solar cell. Wafers are usually polished to remove saw marks, although some manufacturers skip this step because cells with more texture will absorb more light.
Doping
Impurities can now be reintroduced into the Silicon after it has been cleaned. Doping adds foreign material, such as phosphorus ions, to a nugget. Adjusting the ionization rate can precisely control the treatment’s penetration depth. This step is not required if boron is injected as the wafers are sliced, which is the usual process.
Add Electrical Contacts
The electrical connectors used to connect solar cells collect the generated current. Thin metals, like copper or palladium, are used to make these connections, allowing sunlight to penetrate the cell still. The metal is either vacuum evaporated using a photoresist or is coated on the exposed area because wax only covers a fraction of the cells. After the connections are made, the cells are separated by thin strips, often made of copper that has been tin-coated.
Add the Anti-Reflective Coating
With its reflective qualities, Silicon may refract up to 35% of the sunlight it is exposed to. Silicon is covered with anti-reflective material to lessen light loss due to reflection. The procedure often involves silicon oxide or titanium dioxide, which is heated until the molecules boil off and transfer to the latter, where they condense. A high voltage can also sputter the material, which entails removing molecules from the substance and depositing them on Silicon at the opposing electrode.
Encapsulate the Cell
The solar cells are enclosed in silicon rubber or ethylene vinyl acetate before being mounted in an aluminum frame with a backing sheet and a glass or plastic cover.
Conclusion
Solar panels ensure the production of clean, sustainable electrical energy from solar energy. Solar cells convert sunlight into usable energy through the photovoltaic effect. Electricity from solar panels has many benefits, including lowering greenhouse gas emissions and supplying a renewable energy source. The solar panel system is intriguing and crucial for the world to meet its energy needs and help create a greener, more sustainable world.
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