What Is The Structure And Working Principle Of Solar Power Supply System?

With the support of various policies, the development momentum of the new energy industry is good, I believe you are also very curious about this piece of knowledge, so the next Xiaobian will lead you to take a look at the structure and working principle of the solar power supply system?
1. Principle of solar power generation
The solar power generation system mainly includes: solar cell module (array), controller, battery, inverter, user lighting load, etc. The solar cell module and battery are the power system, the controller and inverter are the control and protection system, and the load is the system terminal
1.1 Solar power supply system
Solar cells and batteries constitute the power unit of the system, so the performance of the battery directly affects the operating characteristics of the system
(1) Battery unit:
Due to technical and material reasons, the power generation of a single battery is very limited, the practical solar cell is a battery system composed of a single battery by string and parallel, called a battery module (array) A single battery is a silicon crystal diode, according to the electronic characteristics of semiconductor materials, When sunlight is irradiated on P-N junction composed of two different conductive types of homogeneous semiconductor materials, P-type and N-type, under certain conditions, solar radiation is absorbed by the semiconductor material, and non-equilibrium carriers are generated in the conduction band and valence band, that is, there is a strong built-in electrostatic field of electrons and holes in the barrier area of P-N junction, so that the current density J can be formed under light. Short circuit current Isc, open circuit voltage Uoc If the two sides of the built-in electric field leading electrode and connected to the load, theoretically by the P-N junction, the connection circuit and the load formed a loop, there is a "photogenerated current" flow, the solar cell module to achieve the load power P output
Theoretical studies have shown that the peak power Pk of solar modules is determined by the local average solar radiation intensity and the electrical load (electricity demand) at the end
(2) Electric energy storage unit:
The direct current generated by the solar cell first enters the battery storage, the characteristics of the battery affect the efficiency and characteristics of the system the battery technology is very mature, but its capacity is affected by the end of the electricity demand, sunshine time (generation time), so the battery watt-hour capacity and ampere-hour capacity are determined by the predetermined continuous no sunshine time
1.2 Controller
The main function of the controller is to make the solar power system always near the high power point of the power generation, in order to obtain high efficiency, and the charging control usually adopts pulse width modulation technology, namely PWM control mode, so that the whole system always runs in the area near the high power point Pm Discharge control mainly refers to when the battery lacks power and the system fails. At present, Hitachi has developed a "sunflower" controller that can track both the control point Pm and the sun movement parameters, increasing the efficiency of fixed battery components by about 50%
1.3 DC-AC Inverter
According to the excitation method, the inverter can be divided into self-excited oscillation inverter and other excited oscillation inverter. The main function is to convert the DC of the battery into alternating current through the full bridge circuit. Generally, SPWM processor is used to modulate, filter, boost voltage, etc., to obtain sinusoidal alternating current matching with the lighting load frequency f and rated voltage UN for the use of the system end user.
2, the efficiency of solar power generation system
In the solar power supply system, the total efficiency of the system ηese is composed of the PV conversion rate of the battery module, controller efficiency, battery efficiency, inverter efficiency and load efficiency, but relative to solar cell technology, it is much more mature than the technology and production level of other units such as controllers, inverters and lighting loads. And the conversion rate of the current system is only about 17%, so improve the conversion rate of the battery module, reduce the unit power cost is the focus and difficulty of the industrialization of solar power generation since the advent of solar cells, crystalline silicon as the main material to maintain the dominant position of the current research on the conversion rate of silicon cells, mainly around increasing the energy absorption surface, such as double-sided batteries, reduce reflection; Using the technology of absorbing impurities to reduce the composite of semiconductor materials; Ultra-thin battery; Improve the theory and establish a new model; Condensing battery, etc