⑴Composition of photovoltaic power generation system
The photovoltaic power generation system is mainly composed of photovoltaic modules, inverters, combiner boxes, combiner cables, box transformers and supporting equipment. Other equipment includes lightning protection systems, power distribution cabinets, energy storage equipment, energy storage converters, environmental monitoring systems, Monitoring system and solar tracking system, etc.
①Photovoltaic modules: In the presence of light (sunlight or other light-emitting objects), the battery absorbs light energy, and the accumulation of different signs of electric charge appears at both ends of the battery, that is, a “photo-generated voltage” is generated, which is “photovoltaic volts” effect”. Under the action of the photovoltaic effect, the two ends of the solar cell generate electromotive force to convert light energy into electric energy, which is an energy conversion device. Solar cells are generally silicon cells, which are classified into monocrystalline silicon photovoltaic modules, polycrystalline silicon photovoltaic modules, and amorphous silicon photovoltaic modules.
②Inverter: A device that converts direct current into alternating current. When solar cells and energy storage devices are DC power sources, and the load is an AC load, inverters are indispensable. According to the operation mode, inverters can be divided into independent operation inverters and grid-connected inverters. Independent operation inverters are used for independent operation of photovoltaic power generation systems to supply power to independent loads. Grid-connected inverters are used for grid-connected operation. Photovoltaic power generation system. According to the inverter output waveform, the inverter can be divided into square wave inverter and sine wave inverter. The square wave inverter has simple circuit and low cost, but the harmonic component is large, and it is generally used for a few hundred watts or less. And systems that do not require high harmonics. The sine wave inverter has a high cost, but it can be applied to various loads. The protection functions of the inverter include: overload protection, short circuit protection, reverse connection protection, undervoltage protection, overvoltage protection, overheating protection, etc.
③Power distribution cabinet: The power distribution cabinet of a photovoltaic power station is a power equipment used to receive and distribute electrical energy. It is mainly composed of control appliances (circuit breakers, isolating switches, load switches, etc.), protection appliances (fuse, relay, arrester, etc.), measuring appliances (current transformer, voltage transformer, voltmeter, ammeter, watt-hour meter, power factor meter, etc.) and Current-carrying conductors and other components. According to the location of the equipment, the power distribution cabinet can be divided into indoor power distribution cabinet and outdoor power distribution cabinet: according to the voltage level, it can be divided into high-voltage power distribution cabinet and low-voltage power distribution cabinet; according to the structure, it can be divided into assembly type distribution cabinet. Electric cabinets and complete power distribution cabinets. Small and medium-sized photovoltaic power stations generally have a small power supply range, and the use of low-voltage AC power supply can basically meet the power needs. Therefore, the low-voltage power distribution cabinet system in the photovoltaic power station becomes the power equipment that connects the inverter and the AC load to receive and distribute electrical energy.
④Energy storage equipment: its function is to store the electric energy generated by the photovoltaic module when exposed to light, which can supply power to the load at any time. The basic requirements of photovoltaic power generation for the battery energy storage equipment used are: low self-discharge rate, long service life, strong deep discharge capability, high charging efficiency, low maintenance to maintenance-free, wide operating temperature range and low price. The batteries used in Dayang Power Generation System mainly include lead-acid batteries, cadmium-nickel batteries and lithium batteries. Matching lead-acid batteries above 200Ah. Generally, fixed or industrial sealed maintenance-free lead-acid batteries are used, and the rated voltage of each battery is 2V DC: for lead-acid batteries below 200Ah, small sealed maintenance-free lead-acid batteries are generally used, and the rated voltage of each battery is 12V DC.For energy storage equipment at this stage, lithium batteries are better used in system engineering, and the cost performance and advantages are obvious. Therefore, this site is more recommended to use lithium-ion batteries. As for where to get better lithium-ion ups batteries, we can take a look at the company’s lithium-ion ups batteries-https://www.takomabattery.com/ups -lithium-battery-ultimate-faq-guide/
⑤Energy storage converter: It regulates and controls the charging and discharging conditions of the energy storage device, and controls the electrical energy output of the photovoltaic module energy storage device to the load according to the power demand of the load. It is the core control part of the energy storage system.
⑥Solar tracking system: The solar tracking system is a power device that can ensure that the photovoltaic module is facing the sun at any time, so that the sun’s rays illuminate the photovoltaic module vertically, and can significantly improve the power generation efficiency of the photovoltaic power generation system. Its structure mainly includes: motor (DC, stepping, servo, planetary reduction motor, push rod motor, etc.), worm gear, sensor system, etc.
⑵Main types of photovoltaic power generation
Photovoltaic power generation systems can be divided into grid-connected photovoltaic power generation systems and independent photovoltaic power generation systems according to whether they are connected to the public grid.
The independent photovoltaic power generation system is mainly composed of photovoltaic components, inverters, energy storage equipment, and energy storage converters. Specific working principle: Photovoltaic modules transfer part of the DC power generated by the sun during the day to the inverter into AC power through the controller, and part of the energy storage device is charged; when the sunlight is insufficient, the energy storage device is transferred to the inverter through the inverter. AC load power supply. Independent photovoltaic power stations include power supply systems for villages in remote areas, solar household power systems, communication signal power supplies, cathodic protection, solar street lights, and other independent photovoltaic power generation systems with energy storage equipment.
The biggest feature of the grid-connected photovoltaic power generation system is that the DC power generated by the photovoltaic modules is converted into AC power that meets the requirements of the public grid through the grid-connected inverter, and then directly connected to the public grid. The excess power is fed back to the grid. The grid-connected photovoltaic power generation system directly inputs electrical energy into the grid without the need to configure energy storage equipment, which saves the energy storage and release process of energy storage equipment, and can make full use of the electricity generated by photovoltaic components to reduce energy loss and reduce system costs. However, a dedicated grid-connected inverter is required in the system to ensure that the output power meets the grid’s requirements for power quality indicators such as voltage and frequency. This kind of system can usually use city electricity and photovoltaic modules in parallel as the power source of the local AC load, which reduces the load shortage rate of the entire system. In addition, the grid-connected photovoltaic system can also play a role in the peak regulation of the public grid. However, the grid-connected photovoltaic power generation system, as a kind of distributed power generation system, will have some adverse effects on the traditional power grid based on the centralized power supply system, such as harmonics. Pollution, islanding effect, etc.