Solar Panels convert sunlight into electricity. Solar panels generate Direct Current (DC) electricity which may or may not be converted to Alternating Current (AC) electricity depending on the end use. This is a simple explanation of solar panel working which can be easily understood by anybody.
It must be noted here that, solar panels convert sunlight into electricity and not Sun’s heat into electricity. In fact, with the rise in temperature above that of Standard Test Condition (25 degrees Celsius or 77 degrees Fahrenheit), the efficiency of solar panel decreases. So, the solar panel starts generating electricity with the sunrise and it continues to generate electricity till the sunset.
Solar Panel Construction
Solar Panels consists of various solar cells arranged in a particular order in series and parallel. These cells are generally made up of silicon doped with thin layers of materials called dopants.
These dopants are applied in thin layers to create a layer of either fewer or more electrons. The side with more electrons will act as negative charge and the side with less electrons will act as positive charge. Generally, a thin layer of phosphorous is added on top of silicon as it brings more electrons and so, acts as a negative charge and a layer of boron is added at the bottom of silicon which has fewer electrons and acts as a positive charge.
Solar Panel Working Principle
Solar Panels work on the principle of Photoelectric Effect. According to this principle, when a light shines on a material, the electrons inside the material gain / absorb energy from photons in light and become high in energy. When this energy becomes higher than the binding energy or band gap energy of the material, electrons escape, or, in other words, electrons get emitted from the material.
Solar Panel being a semiconductor device also works on the principal of p-n junction. When we form layers of phosphorous and boron on silicon, it forms a p-n junction. One side of this junction has more electrons than the other side, which makes current to flow in a particular direction.
Solar Panel Working
When not excited by sunlight, electrons from one side find it difficult to go to other side of the junction as more energy is required to counter the opposing electric field.
When solar panel is placed in the sunlight, electrons absorb energy from the sunlight. This makes their energy enough to counter the opposing electric field. As a result, electrons flow from one region to the other region across the p-n junction.
This can be seen in the picture on the left. In the presence of sunlight, electrons are moving from left side to the right side. This causes an accumulation of negative charge on the right side and consequently, positive charge on left side. This creates a voltage difference and thus causes the current to flow in the wire from positive side to negative side as shown in the same figure.
This can be seen as similar to the terminals of a battery. The current flows from positive to negative side powering your loads and appliances.
In order to to capture the charge, metal contacts are provided at both positive and negative terminals. They are then connected to wires or cable for the flow of current.
At this point, solar panels are converting sunlight into DC electricity. This can either be converted into AC using an inverter or can be used directly while employing DC appliances.