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How Does a Solar Panel Work?
Sunlight to electricity? How does a conversion like that take place?
Solar panels are the most well-known source of renewable energy. But how do they work, exactly?
Table of Contents
What do solar panels do?
When most people imagine solar power, they think of giant fields of solar panels, each taking energy from the Sun. This is the most common use of solar panels, but it is only half of the story.
Solar energy and sunlight are terms that are both commonly used, and mostly mean the same thing. Some part of the Earth is always receiving sunlight. As chemical reactions take place within the core of the Sun, it emits heat and light. We experience the heat that the Sun emits, since it makes our planet livable, but this is not what solar panels do. Solar panels make use only of the light.
It is hard to imagine, but light carries energy. Solar panels convert this light energy into electrical energy, but they can also convert it into heat! In large power plants, this heat is used to boil water, and the steam spins turbines. In smaller-scale household setups, solar panels can be used to heat water for bathing and keeping pipes warm in the winter.
Light, heat, and electricity are the three main forms of energy involved with solar panels.
What are solar panels made of?
If you have ever looked at a solar panel closely, you may have noticed it is made up of regular, smaller segments. These segments are squarish and usually deep blue or black. These are known as photovoltaic cells. The most common photovoltaic cells are made of an element called silicon. Silicon is not uncommon in nature, but it is usually found in impure forms, and needs to be refined before it can be used. More recent photovoltaic cells may also use another element called germaninum.
The dark blue or black color of the photovoltaic cell is to ensure that the cell absorbs as much solar energy as possible. Light or white surfaces tend to reflect light. Each photovoltaic cell is connected in a network with others in order to generate electricity from the entire panel.
How does a solar panel work?
In order to get familiar with how solar panels work, we need to introduce two heroes to the story: the photon and the electron.
The light energy coming in from the Sun arrives in the form of an electromagnetic wave. Light does not only behave as a wave. In some situations, light also behaves like it is made up of smaller particles, known as photons. A stubborn law of physics is that things are always made of smaller things. Just as material objects are made of atoms, light is made of photons! Photons carry a lot of energy with them as they move.
An even smaller part of the atom is the electron, which carries negative charge. The electron is the second hero in our story. In some elements, like silicon, the electrons are loosely held to the atom. The slightest push of energy can knock an electron out of the atom.
A photovoltaic cell has two main layers, both made of a compound known as a semiconductor, which is rich in silicon. The top layer is silicon mixed with phosphorus, in a process known as doping. This gives the layer many extra electrons. The bottom layer is silicon mixed with boron, giving the layer fewer electrons than normal. Electrons are negatively charged, and like charges repel. When lots of like charges are stuck in one place together, they want to escape that place.
Photons give that little push of energy necessary to knock electrons out of orbit. When light, and consequently photons, hit the top layer of silicon, the electrons begin moving around. When they move, they jump ship into the bottom layer, which has a deficiency of electrons.
How does a solar panel produce electricity?
Electricity is nothing but the flow of electrons. When electrons move from one place to another, they carry energy, which is known as electricity! Photons force electrons to move, thereby creating electricity
What are the two main disadvantages to solar energy?
One huge disadvantage of solar power is that it is weather-dependent. Solar power works best when the weather is sunny. When it is cloudy or raining outside, solar panels tend not to get enough light to produce energy effectively. This weather-dependence also means that home energy supplies can be very unpredictable. Being stuck in the middle of a storm without power can be a scary prospect, so most home solar setups incorporate some form of backup.
Another major disadvantage is the difficulty of storing solar energy. When do you imagine solar energy production would peak? If you said around noon and in the afternoon, you would be correct. During the nights and early morning, energy production takes a dip. Cooking, lights, air conditioning—all of these might take place at night, and all require energy. Figuring out how to store energy when it is being produced is key to tackling the two main disadvantages of solar panels.
Though solar energy has its disadvantages, solar panels are likely to become very common as renewable energy becomes more popular. What do you think? Would you use a solar panel?
Doping: The process of adding extra charges to a semiconductor material
Electron: A tiny, negatively charged component of an atom
Electromagnetic wave: A type of wave that can travel through space, including light, UV and infra-red waves
Photon: A particle that makes up light
Photovoltaic cells: The single units that make up a solar panel
Semiconductor: A substance with variable electric properties
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