How Do Solar Panels Work?

From the use of sundials for telling the time to using the sun to create fires with magnifying glass, the power of the sun has never been underestimated. Though more accessible use of solar panels to generate electricity for homes has been a relatively new phenomena for people, for reasons such as the introduction of Irish grant schemes in 2021, the power of the sun has been widely utilised throughout time. The first solar panel or roof top photo array ever made was in 1883 by Charles Fritz. As the solar cell efficiency on this was too low for it to be practical it wasn’t until the 1950’s that the first modern solar panels were developed in Bell labs.

Solar panels work by turning the suns light into electricity by a process known as the photovoltaic effect. Solar panels are made of special type of material known as a semiconductor. This is a material that has an electrical conductivity value between that of a conductor and an insulator. An example of such a material is silicon. Solar panels are made up of solar cells. Solar cells are made up of semiconductor materials with different doping levels in order to create a PN junction. Doping is where we add impurities to the materials to change its conductivity. The P-type semiconductor has an excess of the negative charge carriers known as electrons. This is essentially the negatively charged semiconductor. Whereas the N-type semiconductor has an excess of holes which are the positive charge carriers. This is essentially the positively charged semiconductor. For example, silicon can be doped with phosphorous making it N-type doped as this creates an excess of free electrons or it can be P-type doped by adding boron and causing an abundance of holes. When these semiconductors are sandwiched together, they form a PN junction, it allows for electron movement and forms an electric field. There are different types of solar cells these include monocrystalline silicon, where the cells are made from a single silicon crystal, Polycrystalline silicon, where the solar cells are made of multiple small silicon crystals, thin- film solar cells, where the cells are made by placing a thin layer of semiconductor material onto a glass, plastic or metal substrate and multi junction cells which are mase up of layers of multiple semiconductor materials with each layer designed to capture a specific wavelength of light.

The sun produces energy this travels to the earth in the form of electromagnetic waves known as radiation. The light hits the solar panel, the energy is absorbed and transferred to the semiconductor. The absorbed photons from the sunlight energize the electrons in the atom, giving them enough energy to move from a state of lower energy to a state of higher energy, leaving behind holes. As described the solar cell is made up of a PN junction and so this forces electrons to move in specific direction and this movement of electrons generates a an electrical current. The combination of the cell’s voltage and current produced gives rise to the amount of power produced. Power is essentially the amount of energy transformed into an electrical circuit and so is the electricity produced by the solar cell. The electricity produced by a photovoltaic cell is direct current (DC), however most homes require alternating current (AC) power. Therefore, the power generated by the solar panel is then passed through an inverter to transform the power from DC to AC.

Solar panels act as a renewable energy resource. Unlike other means of generating electricity, such as burning fossil fuels, solar panels produce electricity without producing carbon dioxide emissions which are a leading cause of global warming. This makes it a green form of creating energy.

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