一、系统构成

     离网型太阳能光伏发电系统主要由太阳能电池板、蓄电池组、太阳能控制器、变换器和监控系统等五大部分组成。图一为光伏发电系统示意图，图二为系统构成原理框图。各部分的功能和作用是：

1、 光伏电池板：它是光伏发电的核心，其作用是太阳辐射能直接转换为直流电能供给负载或储存在蓄电池中。

2、 光伏控制器：由于一般的单晶硅或多晶硅光伏电池板输出为电流源型，不能直接输出给负载和电池，需要通过光伏控制器将其变换为蓄电池可接受的稳定的电压或电流，实现蓄电池的有效充电或供给外接负载。光伏控制器还能实现对蓄电池组的过冲和过放保护功能。

3、 逆变器；如果要求输出为直流，则可以通过该部分将蓄电池的电压转换成不同的直流电压以适应不同的负载设备。如果输出为交流，则可通过直流电变为交流电 220V(单相）、380V（三相），对于家庭用，该部分一般采购交流逆变器。

4、监控系统：该部分的主要作用是监控各部分的工作参数和工作状态，同时提供人机操作界面。

图一  离网型光伏发电系统示意图

图二、离网型光伏发电构成原理图

二、系统功能及特点 

1、能实现对蓄电池组的恒压、恒流充电和充电过程的自动管理；  

2、具有太阳能最大功率点跟踪控制功能（ MPPT），发挥光伏电池的最大功效；  3 、逆变器交流输出波形正弦度好，输出电压稳定，抗扰能力强； 

4、保护功能完善，具有蓄电池过充、过放、输出过压、过流、短路等多种保护；  

5、具有交流电网供电后备功能，当多日无太阳光照，蓄电池储存电能无法满足输出供电时，系统可自动切换为交流市电供电，由于采用直流侧无间断切换，交流输出无间断现象；  6、友好的人机操作界面、完善的监控功能，系统采用大尺寸触摸液晶屏，操控方便、显示直观；  

三、系统适应领域 

1、家庭供电：特别适用于独立式居住的家庭，如城市别墅区、农村家庭。对于城市居民小区，居住在顶楼的住户或私家阳台较大的家庭也较合适；  

2、学校供电：特别适用于中小学和幼儿园，在这些地方，一般白天用电较多，且用电量不大；  

3、医院供电：可与医院的应急供电系统融合在一起，可有效提高医院的应急电源的可靠性和经济性；  

4、城市小区公共供电：可安装在城市小区公共部分，接入小区的公用电房，作为小区公用电使用；  

3、政府部门、企事业单位办公大楼供电：集中安装在办公大楼的顶层，作为公用电接入大楼低压配电柜中。

I. System structure  

Off-grid solar photovoltaic power generation system is mainly composed of solar panels, batteries, solar controller, converter and monitoring system.  Figure 1 is a schematic diagram of photovoltaic power generation system, and Figure 2 is a block diagram of system composition.  The functions and functions of each part are:  

1, photovoltaic panel: it is the core of photovoltaic power generation, its role is to directly convert solar radiation into direct current power supply load or stored in the battery.  

2, photovoltaic controller: because the output of the general monocrystalline silicon or polysilicon photovoltaic panel is the current source type, it can not be directly output to the load and battery, it needs to be transformed into a stable voltage or current acceptable to the battery through the photovoltaic controller, to realize the effective charging of the battery or supply external load.   The photovoltaic controller can also realize the protection function of overshoot and overdischarge of the battery.  

3. Inverter;  If dc output is required, the battery voltage can be converted to different DC voltages through this part to adapt to different load devices.  If the output is AC, it can be changed into AC 220V(single-phase) and 380V (three-phase) through direct current. For family use, ac inverters are generally purchased for this part.  

4, monitoring system: the main role of this part is to monitor the working parameters and working status of each part, while providing man-machine operation interface.  

FIG. 1 Schematic diagram of off-grid PHOTOVOLTAIC power generation system  

The picture  

Figure 2. Schematic diagram of off-grid photovoltaic power generation  

The picture  

Ii. System functions and characteristics  

1, can realize the battery constant voltage, constant current charging and charging process automatic management;  

2, with solar maximum power point tracking control function (MPPT), to maximize the efficiency of photovoltaic cells;  3, inverter AC output waveform sine, stable output voltage, strong disturbance resistance;  

4, perfect protection function, with battery overcharge, overdischarge, output overvoltage, overcurrent, short circuit and other protection;  

5, with ac power supply backup function, when there is no sunlight for many days, the battery storage energy can not meet the output power supply, the system can automatically switch to AC power supply, because the DC side without interruption switch, AC output without interruption phenomenon;   6, friendly man-machine interface, perfect monitoring function, the system uses large touch LCD screen, easy to control, intuitive display;  

Three, system adaptation field  

1, home power supply: especially suitable for independent living families, such as urban villa areas, rural families.  To city dweller village, the household that lives in the top floor or the family with bigger private balcony is more appropriate also;  

2, school power supply: especially suitable for primary and secondary schools and kindergartens, in these places, generally during the day more electricity, and electricity consumption is not large;  

3, hospital power supply: can be integrated with the hospital emergency power supply system, can effectively improve the reliability and economy of the hospital emergency power supply;  

4, urban community public power supply: can be installed in the public part of the urban community, access to the community of public electricity room, as the community of public electricity use;  

3, government departments, enterprises and institutions office building power supply: centralized installation in the top floor of the office building, as a public power access building low-voltage power distribution cabinet.