太陽能光伏系統(tǒng)的組成和原理

太陽能光伏系統(tǒng)由以下三部分組成：太陽電池組件;充、放電控制器、逆變器、測試儀表和電腦監(jiān)控等電力電子設(shè)備和蓄電池或其他蓄能和輔助發(fā)電設(shè)備。

太陽能光伏系統(tǒng)具有以下的特點：

沒有轉(zhuǎn)動部件，不產(chǎn)生噪音;

沒有空氣污染、不排放廢水;

沒有燃燒過程，不需要燃料;

維修保養(yǎng)簡單，維護(hù)費(fèi)用低;

運(yùn)行可靠性、穩(wěn)定性好;

作為關(guān)鍵部件的太陽電池使用壽命長，晶體硅太陽電池壽命可達(dá)到25年以上;根據(jù)需要很容易擴(kuò)大發(fā)電規(guī)模。

光伏系統(tǒng)應(yīng)用非常廣泛，光伏系統(tǒng)應(yīng)用的基本形式可分為兩大類：獨(dú)立發(fā)電系統(tǒng)和并網(wǎng)發(fā)電系統(tǒng)。應(yīng)用主要領(lǐng)域主要在太空航空器、通信系統(tǒng)、微波中繼站、電視差轉(zhuǎn)臺、光伏水泵和無電缺電地區(qū)戶用供電。隨著技術(shù)發(fā)展和世界經(jīng)濟(jì)可持續(xù)發(fā)展的需要，發(fā)達(dá)國家已經(jīng)開始有計劃地推廣城市光伏并網(wǎng)發(fā)電，主要是建設(shè)戶用屋頂光伏發(fā)電系統(tǒng)和MW級集中型大型并網(wǎng)發(fā)電系統(tǒng)等，同時在交通工具和城市照明等方面大力推廣太陽能光伏系統(tǒng)的應(yīng)用。

光伏系統(tǒng)的規(guī)模和應(yīng)用形式各異，如系統(tǒng)規(guī)模跨度很大，小到0.3～2W的太陽能庭院燈，大到MW級的太陽能光伏電站，如3.75kWp家用型屋頂發(fā)電設(shè)備、敦煌10MW專案。其應(yīng)用形式也多種多樣，在家用、交通、通信、空間應(yīng)用等諸多領(lǐng)域都能得到廣泛的應(yīng)用。盡管光伏系統(tǒng)規(guī)模大小不一，但其組成結(jié)構(gòu)和工作原理基本相同。圖4-1是一個典型的供應(yīng)直流負(fù)載的光伏系統(tǒng)示意圖。其中包含了光伏系統(tǒng)中的幾個主要部件：

光伏組件方陣：由太陽電池元件(也稱光伏電池組件)按照系統(tǒng)需求串、并聯(lián)而成，在太陽光照射下將太陽能轉(zhuǎn)換成電能輸出，它是太陽能光伏系統(tǒng)的核心部件。

蓄電池：將太陽電池元件產(chǎn)生的電能儲存起來，當(dāng)光照不足或晚上、或者負(fù)載需求大于太陽電池元件所發(fā)的電量時，將儲存的電能釋放以滿足負(fù)載的能量需求，它是太陽能光伏系統(tǒng)的儲能部件。目前太陽能光伏系統(tǒng)常用的是鉛酸蓄電池，對于較高要求的系統(tǒng)，通常采用深放電閥控式密封鉛酸蓄電池、深放電吸液式鉛酸蓄電池等。

控制器：它對蓄電池的充、放電條件加以規(guī)定和控制，并按照負(fù)載的電源需求控制太陽電池元件和蓄電池對負(fù)載的電能輸出，是整個系統(tǒng)的核心控制部分。隨著太陽能光伏產(chǎn)業(yè)的發(fā)展，控制器的功能越來越強(qiáng)大，有將傳統(tǒng)的控制部分、逆變器以及監(jiān)測系統(tǒng)集成的趨勢，如AES公司的SPP和SMD系列的控制器就集成了上述三種功能。

光伏逆變器：在太陽能光伏供電系統(tǒng)中，如果含有交流負(fù)載，那么就要使用逆變器設(shè)備，將太陽電池元件產(chǎn)生的直流電或者蓄電池釋放的直流電轉(zhuǎn)化為負(fù)載需要的交流電。

太陽能光伏供電系統(tǒng)的基本工作原理就是在太陽光的照射下，將太陽電池元件產(chǎn)生的電能通過控制器的控制給蓄電池充電或者在滿足負(fù)載需求的情況下直接給負(fù)載供電，如果日照不足或者在夜間則由蓄電池在控制器的控制下給直流負(fù)載供電，對于含有交流負(fù)載的光伏系統(tǒng)而言，還需要增加逆變器將直流電轉(zhuǎn)換成交流電。光伏系統(tǒng)的應(yīng)用具有多種形式，但是其基本原理大同小異。對于其他類型的光伏系統(tǒng)只是在控制機(jī)理和系統(tǒng)部件上根據(jù)實際的需要有所不同，下面將對不同類型的光伏系統(tǒng)進(jìn)行詳細(xì)地描述。

光伏系統(tǒng)的分類與介紹

一般將光伏系統(tǒng)分為獨(dú)立系統(tǒng)、并網(wǎng)系統(tǒng)和混合系統(tǒng)。如果根據(jù)光伏系統(tǒng)的應(yīng)用形式、應(yīng)用規(guī)模和負(fù)載的類型，對光伏供電系統(tǒng)進(jìn)行比較細(xì)致的劃分，可將光伏系統(tǒng)分為如下六種類型：小型太陽能供電系統(tǒng)(SmallDC);簡單直流系統(tǒng)(SimpleDC);大型太陽能供電系統(tǒng)(LargeDC);交流、直流供電系統(tǒng)(AC/DC);并網(wǎng)系統(tǒng)(UtilityGridConnect);混合供電系統(tǒng)(Hybrid);并網(wǎng)混合系統(tǒng)。

光伏發(fā)電是利用半導(dǎo)體介面的光生伏特效應(yīng)而將光能直接轉(zhuǎn)變?yōu)殡娔艿囊环N電子元件技術(shù)，這種技術(shù)的關(guān)鍵元件是太陽能電池。太陽能電池經(jīng)過串聯(lián)后進(jìn)行封裝保護(hù)可形成大面積的太陽電池元件，再配合上功率控制器等部件就形成了光伏發(fā)電裝置。光伏發(fā)電的優(yōu)點是較少受地域限制，因為陽光普照大地;光伏系統(tǒng)還具有安全可靠、無雜訊、低污染、無需消耗燃料和架設(shè)輸電線路即可就地發(fā)電供電及建設(shè)同期短的優(yōu)點。

光伏發(fā)電是根據(jù)光生伏特效應(yīng)原理,利用太陽能電池將太陽光能直接轉(zhuǎn)化為電能。不論是獨(dú)立使用還是并網(wǎng)發(fā)電,光伏發(fā)電系統(tǒng)主要由太陽能電池板(元件)、控制器和逆變器三大部分組成，它們主要由電子元器件構(gòu)成，不涉及機(jī)械部件,所以,光伏發(fā)電設(shè)備極為精煉,可靠穩(wěn)定壽命長、安裝維護(hù)簡便。理論上講,光伏發(fā)電技術(shù)可以用于任何需要電源的場合,上至航天器,下至家用電源,大到兆瓦級電站,小到玩具,光伏電源無處不在。太陽能光伏發(fā)電的最基本元件是太陽能電池(片)，有單晶硅、多晶硅、非晶硅和薄膜電池等。目前，單晶和多晶電池用量最大，非晶電池用于一些小系統(tǒng)和計算器輔助電源等。

Composition and principle of solar photovoltaic system
The solar photovoltaic system consists of the following three parts: solar cell module; Charge and discharge controllers, inverters, test instruments, computer monitoring and other power electronic equipment and batteries or other energy storage and auxiliary power generation equipment.
The solar photovoltaic system has the following characteristics:
No rotating parts, no noise;
No air pollution, no waste water discharge;
No combustion process, no fuel required;
Simple maintenance and low maintenance cost;
Good operation reliability and stability;
As a key component, the solar cell has a long service life, and the service life of crystalline silicon solar cell can reach more than 25 years; It is easy to expand the scale of power generation as required.
Composition, principle and characteristics of solar photovoltaic power generation
Photovoltaic systems are widely used. The basic forms of photovoltaic system applications can be divided into two categories: independent power generation systems and grid connected power generation systems. The main application fields are mainly in space aircraft, communication system, microwave relay station, TV turntable, photovoltaic water pump and household power supply in areas without electricity and power shortage. With the development of technology and the sustainable development of the world economy, developed countries have begun to promote urban photovoltaic grid connected power generation in a planned way, mainly building household roof photovoltaic power generation systems and MW level centralized large-scale grid connected power generation systems, and vigorously promoting the application of solar photovoltaic systems in transportation and urban lighting.
The scale and application forms of photovoltaic systems vary. For example, the scale span of the system is very large, ranging from 0.3 ~ 2W solar garden lamps to MW solar photovoltaic power plants, such as 3.75kwp household roof power generation equipment and Dunhuang 10MW project. Its application forms are also diverse, and it can be widely used in many fields, such as household, transportation, communication, space applications and so on. Although the scale of photovoltaic system varies, its composition structure and working principle are basically the same. Figure 4-1 is a schematic diagram of a typical photovoltaic system supplying DC load. It includes several main components in the photovoltaic system:
Photovoltaic module array: it is composed of solar cell elements (also known as photovoltaic cell modules) in series and parallel according to the system requirements. It converts solar energy into electric energy output under the sunlight. It is the core component of the solar photovoltaic system.
Storage battery: it stores the electric energy generated by the solar cell element. When the light is insufficient or at night, or the load demand is greater than the electric energy generated by the solar cell element, it releases the stored electric energy to meet the energy demand of the load. It is the energy storage component of the solar photovoltaic system. At present, lead-acid batteries are commonly used in solar photovoltaic systems. For systems with high requirements, deep discharge valve regulated sealed lead-acid batteries and deep discharge liquid absorption lead-acid batteries are usually used.
Controller: it regulates and controls the charging and discharging conditions of the battery, and controls the solar cell elements and the electric energy output of the battery to the load according to the power demand of the load. It is the core control part of the whole system. With the development of the solar photovoltaic industry, the functions of the controller are becoming more and more powerful. There is a trend to integrate the traditional control part, inverter and monitoring system. For example, the spp and SMD series controllers of AES company integrate the above three functions.
Photovoltaic inverter: in the solar photovoltaic power supply system, if there is an AC load, the inverter equipment shall be used to convert the DC generated by the solar cell elements or the DC released by the battery into the AC required by the load.
The basic working principle of the solar photovoltaic power supply system is to charge the battery through the control of the controller or directly supply power to the load when the load demand is met under the illumination of the sun. If the sunlight is insufficient or at night, the battery will supply power to the DC load under the control of the controller. For the photovoltaic system with AC load, It is also necessary to add an inverter to convert DC into AC. The application of photovoltaic system has many forms, but its basic principles are similar. For other types of photovoltaic systems, the control mechanism and system components are different according to actual needs. The following will describe different types of photovoltaic systems in detail.
Composition, principle and characteristics of solar photovoltaic power generation
Classification and introduction of photovoltaic system
Generally, photovoltaic system is divided into independent system, grid connected system and hybrid system. If the photovoltaic power supply system is carefully divided according to the application form, application scale and load type of the photovoltaic system, the photovoltaic system can be divided into the following six types: small solar power supply system (smalldc); Simple DC system (simpledc); Large solar power supply system (largedc); AC and DC power supply system (ac/dc); Utility grid connect; Hybrid power supply system; Grid connected hybrid system.
Photovoltaic power generation is an electronic component technology that directly converts light energy into electrical energy by using the photovoltaic effect at the semiconductor interface. The key component of this technology is the solar cell. After the solar cells are connected in series, they can be packaged and protected to form a large area of solar cell elements, and then combined with power controllers and other components to form a photovoltaic power generation device. The advantage of photovoltaic power generation is that it is less restricted by region, because the sun shines on the earth; The photovoltaic system also has the advantages of safety and reliability, no noise, low pollution, local power generation and power supply without fuel consumption and power transmission lines, and short construction period.
Photovoltaic power generation is based on the principle of photovoltaic effect, using solar cells to directly convert solar energy into electric energy. Whether it is used independently or connected to the grid for power generation, the photovoltaic power generation system is mainly composed of solar panels (components), controllers and inverters, which are mainly composed of electronic components and do not involve mechanical parts. Therefore, the photovoltaic power generation equipment is extremely refined, reliable, stable, long service life and easy to install and maintain. Theoretically, photovoltaic power generation technology can be used in any situation that requires power, from spacecraft to household power, from megawatt power stations to toys. Photovoltaic power is everywhere. The most basic components of solar photovoltaic power generation are solar cells (chips), including monocrystalline silicon, polycrystalline silicon, amorphous silicon and thin film cells. At present, single crystal and polycrystalline batteries are the most widely used. Amorphous batteries are used in some small systems and auxiliary power supplies for calculators.