太阳能光伏发电基本原理科普

光伏发电是利用半导体界面的光生伏特效应而将光能直接转变为电能的一种技术。这种技术的关键元件是太阳能电池。太阳能电池经过串联后进行封装保护可形成大面积的太阳电池组件，再配合上功率控制器等部件就形成了光伏发电装置。光伏发电的优点是较少受地域限制，因为阳光普照大地;光伏系统还具有安全可靠、无噪声、低污染、无需消耗燃料和架设输电线路即可就地发电供电及建设同期短的优点。

并网光伏发电就是太阳能组件产生的直流电经过并网逆变器转换成符合市电电网要求的交流电这后直接接入公共电网。并网光伏发电有集中式大型并网光伏电站一般都是国家级电站，主要特点是将所发电能直接输送到电网，由电网统一调配向用户供电。但这种电站投资大、建设周期长、占地面积大，目前还没有太大发展。而分散式小型并网光伏，特别是光伏建筑一体化光伏发电，由于投资小、建设快、占地面积小、政策支持力度大等优点，是目前并网光伏发电的主流。

户用式太阳能发电系统

二、光伏发电的原理

光伏发电，其基本原理就是“光伏效应”。光子照射到金属上时，它的能量可以被金属中某个电子全部吸收，电子吸收的能量足够大，能克服金属内部引力做功，离开金属表面逃逸出来，成为光电子。

白天采用高能vcz晶体发电板和太阳光互感对接和全天候24小时接收风能发电互补，通过全自动接收转换柜接收，直接满足所有家电用电需求。并通过国家信息产业化学物理电源产品质量监督检验中心检测合格。

光照使不均匀半导体或半导体与金属结合的不同部位之间产生电位差的现象。它首先是由光子(光波)转化为电子、光能量转化为电能量的过程;其次，是形成电压过程。有了电压，就像筑高了大坝，如果两者之间连通，就会形成电流的回路。

光伏发电的主要原理是半导体的光电效应。硅原子有4个外层电子，如果在纯硅中掺入有5个外层电子的原子如磷原子，就成为N型半导体；若在纯硅中掺入有3个外层电子的原子如硼原子，形成P型半导体。当P型和N型结合在一起时，接触面就会形成电势差，成为太阳能电池。当太阳光照射到P－N结后，空穴由P极区往N极区移动，电子由N极区向P极区移动，形成电流。

多晶硅经过铸锭、破锭、切片等程序后，制作成待加工的硅片。在硅片上掺杂和扩散微量的硼、磷等，就形成P－N结。然后采用丝网印刷，将精配好的银浆印在硅片上做成栅线，经过烧结，同时制成背电极，并在有栅线的面涂一层防反射涂层，电池片就至此制成。电池片排列组合成电池组件，就组成了大的电路板。一般在组件四周包铝框，正面覆盖玻璃，反面安装电极。有了电池组件和其他辅助设备，就可以组成发电系统。为了将直流电转化交流电，需要安装电流转换器。发电后可用蓄电池存储，也可输入公共电网。发电系统成本中，电池组件约占50%，电流转换器、安装费、其他辅助部件以及其他费用占另外 50%。

三、光伏电站的类型

光伏发电系统分为独立光伏发电系统、并网型光伏发电系统及分布式光伏发电 系统。

1、独立光伏发电也叫离网光伏发电。主要由太阳能电池组件、控制器、蓄电池组成，若要为交流负载供电，还需要配置交流逆变器。独立光伏电站包括边远地区的村庄供电系统，太阳能户用电源系统 ，通信信号电源、阴极保护、太阳能路灯等各种带有蓄电池的可以独立运行的光伏发电系统。

2、并网光伏发电就是太阳能组件产生的直流电经过并网逆变器转换成符合市电电网要求的交流电之后直接接入公共电网。

可以分为带蓄电池的和不带蓄电池的并网发电系统。带有蓄电池的并网发电系统具有可调度性，可以根据需要并入或退出电网，还具有备用电源的功能，当电网因故停电时可紧急供电。带有蓄电池的光伏并网发电系统常常安装在居民建筑；不带蓄电池的并网发电系统不具备可调度性和备用电源的功能，一般安装在较大型的系统上。并网光伏发电有集中式大型并网光伏电站一般都是国家级电站，主要特点是将所发电能直接输送到电网，由电网统一调配向用户供电。但这种电站投资大、建设周期长、占地面积大，还没有太大发展。而分散式小型并网光伏，特别是光伏建筑一体化光伏发电，由于投资小、建设快、占地面积小、政策支持力度大等优点，是并网光伏发电的主流。

3、分布式光伏发电系统，又称分散式发电或分布式供能，是指在用户现场或靠近用电现场配置较小的光伏发电供电系统，以满足特定用户的需求，支持现存配电网的经济运行，或者同时满足这两个方面的要求。　　分布式光伏发电系统的基本设备包括光伏电池组件、光伏方阵支架、直流汇流箱 、直流配电柜、并网逆变器、交流配电柜等设备，另外还有供电系统监控装置和环境监测装置。其运行模式是在有太阳辐射的条件下，光伏发电系统的太阳能电池组件阵列将太阳能转换输出的电能，经过直流汇流箱集中送入直流配电柜，由并网逆变器逆变成交流电供给建筑自身负载，多余或不足的电力通过联接电网来调节。

Photovoltaic power generation is a technology that directly converts light energy into electricity by using the photogenerated volt effect of semiconductor interface.   The key element in this technology is the solar cell.  Solar cells after series packaging protection can form a large area of solar cell components, and then with the power controller and other components to form a photovoltaic power generation device.  Photovoltaics have the advantage of being less localised, since the sun shines; The photovoltaic system also has the advantages of safety and reliability, no noise, low pollution, no need to consume fuel and set up transmission lines to generate electricity and supply power locally, and the construction period is short.  

Grid-connected photovoltaic power generation means that the direct current generated by solar modules is converted into alternating current that meets the requirements of the mains power grid through grid-connected inverter and then directly connected to the public power grid.   Grid-connected photovoltaic power generation centralized large-scale grid-connected photovoltaic power stations are generally national-level power stations, the main feature of which is that the generated energy is directly transmitted to the power grid, and the power grid is unified to supply power to users.  However, this kind of power station has not been developed much because of its large investment, long construction cycle and large area.  And the distributed small-scale grid-connected photovoltaic, especially the integrated photovoltaic power generation of photovoltaic buildings, is the mainstream of grid-connected photovoltaic power generation due to the advantages of small investment, fast construction, small footprint, and large policy support.  

Image of household solar power system  

The principle of photovoltaic power generation  

Photovoltaic power generation, its basic principle is the "photovoltaic effect".  When a photon strikes a metal, its energy can be completely absorbed by an electron in the metal. The energy absorbed by the electron is large enough to overcome the metal's internal gravity to do work, leave the metal surface and escape, becoming a photoelectron.  

During the day, it adopts high-energy VCZ crystal power generation panel and solar light mutual induction docking and round-the-clock wind power generation complementarity. It can directly meet the electricity demand of all household appliances through automatic receiving and conversion cabinet.   And passed the national information industry chemical physical power supply product quality supervision and inspection center test qualified.  

An electric potential difference caused by light exposure in an inhomogeneous semiconductor or between different parts of a semiconductor bound to a metal.   It is first from the photon (light wave) into electrons, light energy into electric energy process;  Second, is the formation of voltage process.  With voltage, it's like building a dam, and if the two are connected, it creates a loop of current.  

The main principle of photovoltaic power generation is the photoelectric effect of semiconductors.  Silicon atoms have four outer electrons. If pure silicon is mixed with an atom with five outer electrons, such as phosphorus, it becomes an N-type semiconductor.  If pure silicon is mixed with atoms with three outer electrons, such as boron atoms, P-type semiconductors are formed.  When the P-type and N-type are combined, the contact surface will form a potential difference and become a solar cell.  When sunlight hits the P-N junction, holes move from the P-pole region to the N-pole region, and electrons move from the N-pole region to the P-pole region, forming an electric current.  The picture  

The polysilicon is made into silicon wafers to be processed after ingot casting, ingot breaking, slice and other procedures.  The P-N junction is formed by doping and diffusing trace amounts of boron and phosphorus on the silicon wafer.  Then using screen printing, the fine silver paste is printed on a silicon wafer to make a grid line. After sintering, the back electrode is made at the same time, and the surface of the grid line is coated with a layer of anti-reflection coating, and the cell sheet is made.  The cells are arranged and combined into battery components to form large circuit boards.   Generally, the components are surrounded by aluminum frames, the front side is covered with glass, and the opposite side is installed with electrodes.  With battery modules and other auxiliary equipment, a power generation system can be formed.  In order to convert direct current to alternating current, a current converter is required.  After generating electricity, it can be stored by battery or input into public power grid.  Battery components account for about 50 percent of the cost of a generation system, and current converters, installation, other ancillary components and other expenses account for another 50 percent.  

3. Types of photovoltaic power stations  

Photovoltaic power generation system is divided into independent photovoltaic power generation system, grid-connected photovoltaic power generation system and distributed photovoltaic power generation system.  

1. Independent photovoltaic power generation is also called off-grid photovoltaic power generation.  It is mainly composed of solar cell modules, controllers, and batteries. To power AC loads, an AC inverter is also required.  Independent photovoltaic power station includes village power supply system in remote areas, solar household power supply system, communication signal power supply, cathodic protection, solar street lamp and other photovoltaic power generation systems with batteries that can operate independently.  

The picture  

2. Grid-connected photovoltaic power generation refers to the direct current generated by solar modules that is converted into alternating current that meets the requirements of the mains power grid by grid-connected inverter and then directly connected to the public power grid.  

It can be divided into grid-connected power generation systems with and without batteries.  The grid-connected power generation system with battery is dispatchable and can be incorporated into or withdrawn from the power grid as required. It also has the function of backup power supply, which can provide emergency power when the power grid fails for some reason.  Grid-connected photovoltaic power systems with batteries are often installed in residential buildings;   Grid-connected power generation systems without batteries do not have the functions of schedulability and backup power supply, and are generally installed in larger systems.  Grid-connected photovoltaic power generation centralized large-scale grid-connected photovoltaic power stations are generally national-level power stations, the main feature of which is that the generated energy is directly transmitted to the power grid, and the power grid is unified to supply power to users.  However, this kind of power station has not been developed much because of its large investment, long construction cycle and large area.  And the distributed small-scale grid-connected photovoltaic, especially the integrated photovoltaic power generation of photovoltaic buildings, is the mainstream of grid-connected photovoltaic power generation due to the advantages of small investment, fast construction, small footprint, and large policy support.  

The picture  

3. Distributed photovoltaic power generation system, also known as distributed power generation or distributed energy supply, refers to the configuration of small photovoltaic power supply system at or near the user site to meet the needs of specific users, support the economic operation of the existing distribution network, or meet the requirements of the two aspects at the same time.   The basic equipment of the distributed photovoltaic power generation system includes photovoltaic cell modules, photovoltaic square support, DC bus box, DC power distribution cabinet, grid-connected inverter, AC power distribution cabinet and other equipment. In addition, there are power supply system monitoring devices and environmental monitoring devices.   Its operation mode is in the solar radiation conditions, photovoltaic power generation system of solar cell module array to convert solar energy output power, a dc bus concentrated into dc power distribution cabinet, by the grid inverter inverter into alternating current supply of building their own load, excess or shortage of electricity through the grid to adjust.