What is a Solar Panel?
Updated: Nov 30, 2020
#Solar energy is abundant and renewable energy. You might have seen solar panels on rooftops of houses offices. You might have heard about solar parks, solar vehicles. In this article, you'll get to learn about solar panels.
Construction of solar panel
Silicon is doped with impurities to form P-type and N-type layers. The topmost layer of a solar panel is an anti-reflective coating. The anti-reflective coating protects solar panels from dust, moisture and absorbs light. Beneath the anti-reflective coating, there is an N-type layer and a P-type layer.
The thickness of the N-type layer is more than the thickness of the P-type layer. The N-type layer is more heavily doped than the P-type layer. Between the N-type layer and P-type layer, a junction or depletion layer is formed. A junction box is provided on the backside of the solar panel for a waterproof wiring connection.
How do solar panels work?
Keeping in mind the construction of solar panels, the N-type layer contains negatively charged particles known as electrons. The P-type layer contains several positively charged holes. Electrons try to move towards the P-type layer. Holes try to move towards the N-type layer. This leads to the formation of a depletion layer or junction. Solar rays or light rays contain photon particles.
When solar light rays penetrate the N-type layer and the depletion layer, electrons get excited and start flowing from the N-type layer to the P-type layer through an external electrical circuit. This unidirectional flow of electrons results in electrical energy. A single #solar cell can produce 0.5V. The power produced by solar cells is DC in nature.
Types of solar panels
Monocrystalline solar panel
Polycrystalline solar panel
Thin-film solar panel
Monocrystalline solar panel
Bars of single Silicon crystals are sliced to produce a solar cell. Monocrystalline solar panels are relatively more efficient than Polycrystalline solar panels. These panels are expensive than polycrystalline panels.
Polycrystalline solar panel
Multiple silicon fragments are melted to form a wafer. Polycrystalline solar panels are less efficient. These panels are cheaper than monocrystalline panels.
Thin-film solar panels
A thin layer of photovoltaic substance is deposited on glass or plastic substrate. These solar panels are thin and flexible and lower in weight. The thickness of the thin-film solar panel ranges from a few nanometers to hundreds of micrometers. Thin-film solar panels are less efficient and cheaper than monocrystalline and polycrystalline solar panels.
Some types of thin-film solar panels are mentioned below.
Amorphous solar panel
Cadmium Telluride ( CdTe ) solar panel
Copper gallium indium diselenide (CIGS) solar panel
The efficiency of solar panels
The efficiency of solar panels may vary depending on its thermodynamic efficiency limit, reflectance, charge carrier separation, and conduction values. The maximum efficiency till now achieved by a multi-junction concentrator photovoltaic cell is 47.1%.
The efficiency of a monocrystalline solar cell is 20 - 25 %.
The efficiency of a thin-film solar cell is 13 - 15 %.
The efficiency of a polycrystalline solar cell is 14 - 19 %.
Efficiency may decrease by a small amount after several years due to the deposition of dust and particles on solar panels.
Lenses, mirrors are used to concentrate more solar light on a solar cell. Cooling systems are also used to achieve high efficiency. This technology is known as CPV ( concentrated photovoltaic cells ).
Solar panel cost
The cost of solar panels may vary depending upon its output voltage and power ratings.
Considering an example,
12 volt, 50 watt - monocrystalline panel costs around 2000 - 2500 Rs.
12 volt, 50 watt - polycrystalline panel costs around 1500 - 1700 Rs.
Issues with solar panels
Solar energy is dependent on the weather.
Solar energy is available in less amount to non-sunshine countries.
Power obtained from the solar cells is DC in nature.
Solar energy is abundantly available to sunshine countries. Countries that lie between the tropic of Cancer and the tropic of Capricorn are sunshine countries.
International Solar Alliance is an initiative by India and France which proposes a global solar power grid offering solar energy to non-sunshine countries.
Applications of solar panels
Solar panels are installed on rooftops of households, the power generated by these panels is then stored in batteries. Power is stored in batteries. It can be used for using home electrical appliances.
Many solar panels are installed on huge open spaces like desserts, airports, and dedicated solar power plants. Power from these panels is transformed from DC to AC using inverter circuits and then fed to a transformer. Then this power is transmitted over long distances. Many industries and power generation companies have their own solar parks. Thin-film and CPV type of solar panels are generally used in solar parks.
Solar panels in space
Satellites, spaceships, and space stations are powered using solar panels. Batteries are installed to store electric energy. Special solar panels are manufactured according to space environmental conditions.
Solar panels can be installed on vehicles such as boats, cars, helicopters, rapid transit systems. This area is currently under research and development. Many concepts and designs are revealed till now. An efficient commercial vehicle is not available as such. Many car manufacturers are working on these concepts. They aim to start the production of commercial solar cars by 2021.
Solar panels are costly, but they are a one-time investment. Though efficiency is less, solar panels provide free, green, clean energy. Solar panels are being used in many areas. Solar panels are a need for the future.