First, the principle of solar power:
(a) How does a solar cell work?
The working principle of crystalline silicon n/p type solar cell: When the p-type semiconductor and the n-type semiconductor are tightly connected together, a p-n junction is formed at the interface between the two. When the photocell is illuminated by sunlight, positive and negative charges are accumulated on both sides of the p-n junction, resulting in a photo-generated voltage and a built-in electric field. This is the “photovoltaic effect”. Theoretically, at this time, if the electrodes are drawn on both sides of the built-in electric field and an appropriate load is connected, a current will be formed and the power will be obtained from the load. Solar cell modules are solid devices that use P-V conversion using the electronic properties of semiconductor materials.
(b) Basic composition of solar energy system
As shown in the above figure, the solar power system consists of a solar module, a solar controller, and a battery (group). If the output power is AC 220V or 110V, you also need to configure the inverter.
(c) The role of each part is
Solar panels: Solar panels are a core part of solar power systems and the most valuable part of solar power systems. Its role is to convert the sun's radiant power into electrical energy, or send it to a storage battery, or push a load to work.
Solar controller: The function of the solar controller is to control the working status of the entire system and play the role of overcharge protection and over-discharge protection of the battery. In areas with large temperature differences, qualified controllers should also have temperature compensation. Other additional functions such as light-controlled switches and time-controlled switches should be optional for the controller.
Storage batteries: Generally lead-acid batteries, nickel-metal hydride batteries, nickel-cadmium batteries, or lithium batteries can also be used in small-scale micro-systems. Its role is to store the electric energy emitted by the solar panel when there is light, and release it when needed.
Inverter: The direct output of solar energy is generally 12VDC, 24VDC, 48VDC. In order to supply electric energy to 220VAC electric appliances, it is necessary to convert the DC electric energy generated by the solar power generation system into AC electric energy, and therefore it is necessary to use a DC-AC inverter. Efficiency is one of the important criteria when choosing an inverter. The higher the efficiency, the less the power loss in the process of converting the direct current generated by the photovoltaic components into alternating current. It can be said that the quality of the inverter determines the efficiency of the power generation system, which is the core of the solar power system.
(d) Main factors to be considered in the design of solar power systems:
Where is the solar power system used and how is the solar radiation in the area?
How much load power does the system have?
What is the output voltage and frequency of the system, DC or AC?
How many hours does the system need to work every day?
If there is rainy weather without sunlight, how many days does the system need to supply power continuously?
In the case of a load, is it resistive, capacitive or inductive, and what is the starting current?
Second, solar power technology applications:
The solar photovoltaic power generation system is a power generation and power conversion system that consists of photovoltaic panels, controllers, and energy storage and conversion links. With the rapid development of the global photovoltaic industry, from the production of panels to the design of power electronic inverters, numerous photovoltaic power generation related technologies have been greatly developed. For a photovoltaic power generation system, solar cell technology, photovoltaic arrays, the largest Maximum PowerPoint Tracking (MPPT) technology, concentrator technology, and islanding detection technology are all important technologies involved in system operation.
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