Popular Science: How Photovoltaic Power Generation?
Jan 05, 2018
Photovoltaic power generation is a technology that utilizes the photovoltaic effect of a semiconductor interface to convert light energy directly into electricity. The photovoltaic power generation is mainly composed of three parts of a solar panel (a module), a controller and an inverter. The main components are composed of electronic components . So, what is a specific process? Here, we will come to a detailed analysis, the photovoltaic power generation process is what?
About semiconductors
Silicon crystal chemistry is very stable. At room temperature, except hydrogen fluoride, it is difficult to react with other substances and is a poor conductor because it has no idle free electrons. The phosphorus atoms (P) of the outermost five electrons, the phosphorus atoms into the silicon crystal, then the silicon crystal is obviously an extra free electrons.
Phosphorus atoms take out four electrons and the adjacent four silicon atoms share, there is an electron remaining, it is free. Numerous silicon atoms in silicon crystals are replaced by phosphorus atoms, giving rise to a lot of free electrons, so that it conducts electricity. At this point, we have made a semiconductor, its name is "N-type semiconductor."
After doping with aluminum atoms, it is clear that there is an electron missing. Silicon doping with trivalent atoms such as aluminum and boron results in another type of semiconductor called "P-type semiconductor" P "Imagine a hole that requires electrons to fill.
P-type semiconductor is also conductive, because after the application of an external electric field, the electrons in the P-type semiconductor sequentially fill holes in the opposite electric field direction, and at the same time, the holes move in the direction of the electric field, so that current is generated.
About PN junction
If one side of a semiconductor crystal is an N-type semiconductor and the other side is a P-type semiconductor, the contact surface in the middle is called a PN junction. In N-type semiconductors, the concentration of free electrons is high, whereas in P-type semiconductors, the concentration of holes is high. According to the principle of diffusion, substances always diffuse from high concentrations to low concentrations.
Therefore, in the PN junction, there will be a lot of free electrons from the N-type semiconductor to the P-type semiconductor diffusion, the result is that the N-type semiconductor is electrically neutral, not charged, but because of the loss of some of the electrons, It is positively charged. In the P-type semiconductor, because many free electrons ran to fill a lot of holes, resulting in reduced hole concentration, the original P-type semiconductor is also electrically neutral, now more than a lot of electronic, so bring Negative electricity.
In the PN junction, one side is positively charged and the other side is negatively charged, thus forming an internal electric field at the contact surface.
What is the photovoltaic power generation process?
When sunlight shines on a typical semiconductor, electrons and holes are generated. That is, when sunlight generates a free electron in a semiconductor, a hole is generated at the same time because the electron leaves the solar cell The position to be, when becoming a free electron, that position necessarily lacks an electron, and holes are created.
Because there is an internal electric field in the PN junction, when the sunlight generates electrons and holes in the PN junction, the electrons move to the N-type semiconductor under the action of the internal electric field. Similarly, the holes move to the P-type semiconductor. At this point, if the PN junction connected to both ends of the wire, you can generate current.
