It is amazing that we can convert sunlight into energy and electricity through the use of solar panels. Read more and discover how solar panels work.
Quick summary: How solar panels work
What is a Solar Panel?
Solar panels or modules are the glass-like devices that are often installed on the roof or in any other suitable location. The modules are usually fixed in a way that allows them to face the direction of the sun.
Solar panels differ in appearance because there are three different types: monocrystalline, polycrystalline, and thin film amorphous solar modules. The three types not only differ in appearance but also efficiency, which is a crucial factor in any installed solar power system.
What Are Solar Panels Made Of?
Solar panels consist of many small units called solar cells that are connected in series. Each of these cells is made up of thin silicon wafers.
Silicon is a semiconductor material. In nature, it exists as a hard and brittle crystalline solid that belongs to the carbon family. In the making of solar cells, silicon is doped with elements such as boron and gallium to improve its electrical properties.
Silicon is preferred when it comes to the making of the cells because it has several advantages over the others. They include availability and the fact that it is easy to melt and mold into the required size and shape.
The many solar cells in a panel are coated with an anti-reflective material. This ensures that maximum sunlight falls on the surface and that the sun’s energy is absorbed rather than reflected. A solar panel also consists of a glass cover whose role is to protect solar cells from getting damaged.
How Do Solar Panels Work?
The conversion of sun rays into electricity by solar panels is an interesting process that is made possible by:
- P-type and N-type layers
- The photovoltaic effect
P-type and N-type layers
Each solar panel is designed in such a way that it has two semiconductor layers, the p-type and the n-type. The two are separated by a p-n junction.
P-type, in simple terms, means that this section is positively charged. This layer is found at the lower side of the panel.
On the other hand, n-type indicates that this semiconductor section is negatively charged. The n-type layer is located on the upper side of the panel, where it is exposed to the sun.
The two semiconductors layers are doped, meaning that they are added with another element that is lacking or has an extra electron. This is done to create an imbalance that will facilitate the movement of free electrons, which are negatively charged.
How Solar Panels Work in Less Than 3 Minutes!
The Photovoltaic Effect
The conversion of light into electricity by a solar panel is made possible by the photovoltaic effect. This is a physical and chemical process that allows certain materials to produce an electric voltage or current when struck by a ray of sun.
Under normal conditions, the solar cells are inactive because their atoms are firmly held together. This means that there are no free electrons.
However, this changes when energy particles from the sun, called photons, falls on the panel. They are absorbed by the cells, thereby energizing the layers. This allows electrons to break free from the atoms of the semiconductor material.
Since the p-type and n-type layers have opposite charges, electrons attempt to move across the positive-negative junction after they are separated from the atoms.
The junction is designed in such a way that it only allows electrons to move from the p-type to the n-type layer. The movement of the electrons creates a difference in electrical potential, which then results in the flow of current.
Solar energy capitalize on this, where the cells are provided with an external circuit that facilitates the flow of the produced electricity into the output terminals of the panel. It is then directed into the house by electrical cables.
Depending on the nature of the solar power system, the produced electricity can be fed into a battery bank, an inverter, or can even be used directly.
How Much Energy Does a Solar Panel Produce?
The photovoltaic effect dictates the amount of electricity produced by a panel. The amount of electricity that is produced by a solar panel is dependent on the photovoltaic effect, which is also influenced by the intensity of the sun.
When brighter sunlight strikes all the solar cells in a given module, many electrons are loosened. This allows them to move freely across the junction, creating a higher electrical difference, which translates to more electricity.
However, when only a few cells are exposed to sunlight, there is a decrease in the overall output of the panel since there are few free electrons. This is why you should ensure that there is no shading on any part of an installed solar panel.
However, it is worth noting that panels are also fitted with bypass diodes. Since solar cells are connected in series, failure of one or more of them can affect the output of a solar module.
This is the reason why panels are fitted with bypass diodes, which ensure that electricity flow over shaded cells that are not producing any current.
Regardless, bypassing does not improve the efficiency of a solar module since it works best when all the cells are absorbing photons and producing electricity.
What Kind of Electricity is Produced by a Solar Panel? DC vs AC
Solar panels produce direct current (DC). Direct current is a type of electricity that involves the flow of electrons in one direction that is from the negative to the positive terminals of an electrical circuit.
DC electricity can be used in that form, or it can be converted into alternating current (AC) by an inverter.
Alternating current (AC) refers to a type of electricity where the electrons change direction periodically. At one time, they are flowing in the forward direction and the next time in reverse.
In solar power systems, AC electricity is commonly used at home as opposed to DC for two main reasons:
- Most of the electrical devices and appliances available in the market use AC power.
- Unlike DC electricity, AC can be transferred over long distances without significant loss of energy. Alternating current is made possible by the fact that the voltage can be stepped-up (increased) or stepped-down (decreased) using transformers found in electrical appliances. AC is safer to use at home because the voltage can be reduced to the appropriate value depending on the need.
Definition of Terms
- Semiconductor – Any material whose electrical properties lie between that of a good conductor of electricity and an insulator. Hence, it is neither a good conductor nor a good insulator.
- Photovoltaic – The science of converting sunlight into electricity using photovoltaic cells which are made using semiconductor materials.
- Electrons – They are the negatively charged subatomic particles found outside the nucleus of an atom. They are responsible for the flow of current from one atom to the other.
- Photons – They are the fundamental particles of light that contains energy. The energy is used to separate electrons from their atoms in a semiconductor material.
- Silicon – It is a chemical element with semiconducting properties and is usually used to make solar cells.
- Doping – It is the introduction of impurities to a semiconductor material to improve its electrical properties.