Photovoltaic power generation is a technology that directly converts light energy into electricity by using the photovoltaic effect at the semiconductor interface and consists of three major components: solar panels (modules), controllers, and inverters, with the main components made up of electronic components. So, what is the specific process? Here, we will analyze in detail, what is the process of photovoltaic power generation?
About semiconductors
Silicon crystals are chemically very stable. At room temperature, it is difficult to react with substances other than hydrogen fluoride and is a poor conductor because it has no free electrons to do anything. The phosphorus atom (P), on the other hand, has five electrons in its outermost layer, and by doping the phosphorus atom into the silicon crystal, then the silicon crystal obviously has an extra free electron.
After the phosphorus atom takes out four electrons to share with the four adjacent silicon atoms, there is one electron left, which is free. When the countless silicon atoms in the silicon crystal are replaced by phosphorus atoms, there are a lot more free electrons, so it conducts electricity. At this point, we have made a semiconductor, which is called an "N-type semiconductor".
After the doping of aluminum atoms, obviously, there is a lack of electrons, silicon crystals doped with trivalent atoms such as aluminum, boron, made another semiconductor, called "P-type semiconductors", you can imagine the "P" as a need for electrons to fill the hole.
P-type semiconductors are also conductive, because, after the application of an external electric field, the electrons in the P-type semiconductor will fill the holes in turn against the direction of the electric field, and at the same time, the holes also move in the direction of the electric field, so that the current is generated.
About PN junction
If a semiconductor crystal has an N-type semiconductor on one side and a P-type semiconductor on the other side, the contact surface in the middle is called a PN junction. In an N-type semiconductor, the concentration of free electrons is high, while in a P-type semiconductor, the concentration of holes is high. According to the principle of diffusion, substances always diffuse from the place of high concentration to the place of low concentration.
Therefore, in the PN junction, there will be a lot of free electrons diffusing from the N-type semiconductor to the P-type semiconductor, bringing the result that the N-type semiconductor, which is originally electrically neutral and not charged, becomes positively charged because of the loss of some electrons. And in the P-type semiconductor, because many free electrons run over, filling a lot of holes, resulting in a decrease in the concentration of holes, the P-type semiconductor is also electrically neutral, but now there are many more electrons, so bring a negative charge.
In a PN junction, one side is positively charged and one side is negatively charged, so an internal electric field is formed at the contact surface.
What is the photovoltaic power generation process?
When sunlight hits a normal semiconductor, electron-hole pairs are created, i.e., when sunlight creates a free electron in a semiconductor, a hole is created at the same time, because when the electron leaves the position where it should have been under the effect of sunlight energy and becomes a free electron, that position is bound to lack an electron and a hole is created.
Because there is an internal electric field in the PN junction when the sunlight produces electrons and holes in the PN junction, the electrons will move to the N-type semiconductor under the action of the internal electric field, and similarly, the holes move to the P-type semiconductor. At this point, if the PN junction is connected to the wire at both ends, it can produce current.
