光伏離網(wǎng)系統(tǒng)沒有統(tǒng)一的規(guī)格，要根據(jù)用戶的需求去設計，主要考慮組件、逆變器、控制器、蓄電池，電纜、開關等設備的選型和計算。設計之前，前期工作要做好，需要先了解用戶的負載類型和功率，安裝地點的氣候條件，用戶的用電量，需求弄清楚后，方可做好方案。

1、組件的電壓和蓄電池的電壓要匹配，PWM型控制器太陽能組件和蓄電池之間通過一個電子開關相連接，中間沒有電感等裝置，組件的電壓是蓄電池的電壓1.2-2.0倍之間，如果是24V的蓄電池，組件輸入電壓在30-50V之間，MPPT控制器，中間有一個功率開關管和電感等電路，組件的電壓是蓄電池的電壓1.2-3.5倍之間，如果是24V的蓄電池，組件輸入電壓在30-90V之間。

2、組件的輸出功率和控制器的功率要相近，如一個48V30A的控制器，輸出功率為1440VA，組件的功率應該在1500W左右。選擇控制器時，先看蓄電池的電壓，再用組件功率除以蓄電池的電壓，就是控制器的輸出電流。

3、如果一臺逆變器功率不夠，需要多臺逆變器并聯(lián)，光伏離網(wǎng)系統(tǒng)輸出連接負載，每個逆變器輸出端電壓和電流相位和幅值都不一樣，逆變器如果輸出端并聯(lián)，要加上有并機功能的逆變器。

離網(wǎng)系統(tǒng)調(diào)試時常見問題

1

逆變器LCD沒有顯示

01

故障分析

沒有蓄電池直流輸入，逆變器LCD電源是由蓄電池供電的。

02

可能原因

（1）蓄電池電壓不夠。蓄電池剛出廠時，一般都會充滿電，但蓄電池如果長時間不用，也會慢慢放完（自放電）。離網(wǎng)系統(tǒng)電壓有12V、24V、48V、96V等多種，有的應用要多個蓄電池串聯(lián)才到滿足系統(tǒng)電壓，如果連接電纜沒做好，也會造成蓄電池電壓不夠。

（2）蓄電池端子接反。蓄電池端子有正負兩極，一般是紅色接正極，黑色接負極。 

（3）直流開關沒有合上或開關故障。

03

解決辦法

（1）如果是蓄電池電壓不夠，系統(tǒng)不能工作，太陽能不能給蓄電池充電，要去另外找一個地方先把蓄電池充到30%以上。

（2）如果是線路的問題，用萬用表電壓檔測量各個蓄電池電壓。電壓正常時，總電壓是各蓄電池電壓之和。如果沒有電壓，依次檢測直流開關，接線端子，電纜接頭等是否正常

（3）如果蓄電池電壓正常，接線正常，開關也打開了，逆變器還是沒有顯示，則可能是逆變器發(fā)生故障，要通知廠家檢修。

2

蓄電池不能充電

01

故障分析

蓄電池是通過光伏組件和控制器，或者市電和控制器來充電的。

02

可能原因

（1）組件原因：組件電壓不夠，陽光偏低，組件和直流電纜接線不好。

（2）蓄電池電路接線不好。

（3）蓄電池已充滿，達到最高電壓。

03

解決辦法

（1）依次檢測直流開關、接線端子、電纜接頭、組件、蓄電池等是否正常。如果有多路組件，要分開單獨接入測試。

（2）當蓄電池達到滿荷電時，就不能再充電了，但不同的蓄電池充滿電時電壓不一樣，如額定電壓為12V的蓄電池，充滿電時電壓在12.8~13.5V之間，主要和蓄電池滿荷電時的電解液比重有關。要根據(jù)蓄電池的型號調(diào)整最高限壓。

（3）輸入過流：蓄電池的充電電流一般為0.1C-0.2C，最大不超過0.3C，例如1節(jié)鉛酸蓄電池12V200AH，充電電流一般在20A到40A之間，最大不能超過60A。組件功率要和控制器功率相配合。

（4）輸入過壓：組件輸入電壓過高，檢查電池板電壓，若確實高，可能原因為電池板配置串數(shù)過多，減少電池板串數(shù)

3

逆變器顯示過載或者不能啟動

01

故障分析

負載功率大于逆變器或者蓄電池功率。

02

可能原因

（1）逆變器過載：逆變器過載超出時間范圍，負載功率超出最大值，調(diào)整負載大小。

（2）蓄電池過載：放電電流一般為0.2C-0.3C，最大不超過0.5C，1節(jié)12V200AH鉛酸蓄電池，輸出最大功率不超過2400W，不同的廠家，不同的型號，具體的數(shù)值也不一樣。

（3）負載是電梯之類的負載不能直接和逆變器輸出端相連接，因為電梯在下降時，電動機反轉(zhuǎn)，會產(chǎn)生一個反電動勢，進入逆變器時，對逆變器有損壞。如果必須要用離網(wǎng)系統(tǒng)，建議在逆變器和電梯電動機之間加一個變頻器。

（4）感性負載啟動功率過大。

03

解決辦法

負載的額定功率要低于逆變器功率，負載的峰值功率不能大于逆變器額定功率的1.5倍。

蓄電池常見問題

1

短路現(xiàn)象及原因

鉛酸蓄電池的短路是指鉛酸蓄電池內(nèi)部正負極群相連。鉛酸蓄電池短路現(xiàn)象主要表現(xiàn)在以下幾個方面：

開路電壓低，閉路電壓(放電)很快達到終止電壓。大電流放電時，端電壓迅速下降到零。開路時，電解液密度很低，在低溫環(huán)境中電解液會出現(xiàn)結(jié)冰現(xiàn)象。充電時，電壓上升很慢，始終保持低值(有時降為零)。充電時，電解液溫度上升很高很快。充電時，電解液密度上升很慢或幾乎無變化。充電時不冒氣泡或冒氣出現(xiàn)很晚。

造成鉛酸蓄電池內(nèi)部短路的原因主要有以下幾個方面：

隔板質(zhì)量不好或缺損，使極板活性物質(zhì)穿過，致使正、負極板虛接觸或直接接觸。隔板竄位致使正負極板相連。極板上活性物質(zhì)膨脹脫落，因脫落的活性物質(zhì)沉積過多，致使正、負極板下部邊緣或側(cè)面邊緣與沉積物相互接觸而造成正負極板相連。導電物體落入電池內(nèi)造成正、負極板相連。

2

極板硫酸化現(xiàn)象及原因

極板硫酸化系是在極板上生成白色堅硬的硫酸鉛結(jié)晶，充電時又非常難于轉(zhuǎn)化為活性物質(zhì)的硫酸鉛。鉛酸酸蓄電池極板硫酸化后主要有以下幾種現(xiàn)象：

（1）鉛蓄電池在充電過程中電壓上升的很快，其初期和終期電壓過高，終期充電電壓可達2.90V／單格左右。

（2）在放電過程中，電壓降低很快，即過早的降至終止電壓，所以其容量比其它電池顯著降低。

（3）充電時，電解液溫度上升的快，易超過45℃。

（4）充電時，電解液密度低于正常值，且充電時過早地發(fā)生氣泡。

 造成極板硫酸化主要有以下幾方面的原因：

（1）鉛蓄電池初充電不足或初充電中斷時間較長。

（2）鉛蓄電池長期充電不足。

（3）放電后未能及時充電。

（4）經(jīng)常過量放電或小電流深放電。

（5）電解液密度過高或者溫度過高，硫酸鉛將深入形成不易恢復。

（6）鉛酸蓄電池擱置時間較長，長期不使用而未定期充電。

There is no unified specification for photovoltaic off-grid system. It should be designed according to the needs of users, mainly considering the selection and calculation of components, inverters, controllers, batteries, cables, switches and other equipment.   Before the design, the preliminary work should be done well. It is necessary to understand the user's load type and power, the climatic conditions of the installation site, and the user's electricity consumption. After the demand is clear, the plan can be done well.  

 

 

 

 

 

The picture  

1, the voltage of the component and the voltage of the battery to match, PWM controller between the solar module and the battery through an electronic switch connected, there is no inductive device in the middle, the voltage of the component is between 1.2-2.0 times the voltage of the battery, if it is the 24V battery, the input voltage of the component is between 30-50V, MPPT controller,   There is a power switch tube and inductor circuit in the middle, the voltage of the component is between 1.2-3.5 times of the voltage of the battery, if it is a 24V battery, the input voltage of the component is between 30-90V.  

 

 

 

2, the output power of the component and the power of the controller should be close, such as a 48V30A controller, the output power is 1440VA, the power of the component should be about 1500W.   When selecting the controller, first look at the battery voltage, and then divide the component power by the battery voltage, is the output current of the controller.  

 

 

 

3, if an inverter power is not enough, the need for multiple inverters in parallel, photovoltaic off-grid system output connection load, each inverter output voltage and current phase and amplitude are different, if the inverter output parallel, to add a parallel function of the inverter.  

 

 

 

The picture  

Common problems during off-network system debugging  

 

 

1  

 

The inverter LCD is not displayed  

01  

Failure analysis  

 

There is no battery DC input, the inverter LCD power supply is powered by the battery.  

 

02  

Possible reasons for  

 

(1) Battery voltage is not enough.  When the battery just leaves the factory, it is generally full of electricity, but if the battery is not used for a long time, it will slowly run out (self-discharge).  Off-grid system voltage is 12V, 24V, 48V, 96V and other kinds of, some applications to multiple battery series to meet the system voltage, if the connection cable is not good, will also cause battery voltage is not enough.  

 

(2) The battery terminal is improperly connected.  Battery terminals have positive and negative poles, usually red to the positive pole and black to the negative pole.  

 

(3) Dc switch is not closed or the switch is faulty.  

 

03  

The solution  

 

(1) If the battery voltage is not enough, the system can not work, the solar energy can not charge the battery, to find another place to charge the battery to more than 30%.  

 

(2) If it is the fault of the line, use a multimeter to measure the voltage of each battery.  When the voltage is normal, the total voltage is the sum of all battery voltages.  If there is no voltage, check whether the DC switch, wiring terminals, and cable connectors are normal  

 

(3) If the battery voltage is normal, the wiring is normal, the switch is opened, and the inverter is still not displayed, the inverter may be faulty, and the manufacturer should be notified for maintenance.  

 

 

 

2  

 

The battery cannot be charged  

 

01  

Failure analysis  

 

Batteries are charged by photovoltaic modules and controllers, or mains and controllers.  

 

02  

Possible reasons for  

 

(1) Component cause: component voltage is insufficient, sunlight is low, and the connection between component and DC cable is not good.  

 

(2) The battery circuit is not connected properly.  

 

(3) The battery is full and reaches the maximum voltage.  

 

03  

The solution  

 

(1) Check the DC switches, wiring terminals, cable connectors, components, and batteries in sequence.  If there are multiple components, connect them separately for testing.  

 

(2) when the battery is fully charged, it can no longer be charged, but the voltage is not the same when the battery is fully charged, such as the rated voltage of 12V battery, when the voltage is fully charged between 12.8 and 13.5V, mainly related to the proportion of electrolyte when the battery is fully charged.   Adjust the maximum voltage limit according to the type of the battery.  

 

(3) Input overcurrent: The charging current of batteries is generally 0.1C-0.2c, and the maximum charging current is no more than 0.3c. For example, the charging current of a lead-acid battery 12V200AH is generally between 20A and 40A, and the maximum charging current cannot exceed 60A.   The component power must be matched with the controller power.  

 

(4) Input overvoltage: The input voltage of the component is too high. Check the voltage of the panel. If it is indeed high, the possible reason is that the number of panels is too many and the number of panels is reduced  

 

 

 

3  

 

The inverter shows overload or does not start  

01  

Failure analysis  

 

The load power is greater than that of the inverter or battery.  

 

02  

Possible reasons for  

 

(1) Inverter overload: the inverter overload exceeds the time range, and the load power exceeds the maximum value. Adjust the load size.  

 

(2) Battery overload: the discharge current is generally 0.2C-0.3c, and the maximum is no more than 0.5C. The maximum output power of one 12V200AH lead-acid battery is no more than 2400W. Different manufacturers and models have different specific values.  

 

(3) The load is the load such as the elevator can not be directly connected to the output end of the inverter, because when the elevator falls, the motor reverses, and a back electromotive force will be generated. When entering the inverter, the inverter will be damaged.   If off-grid system must be used, it is recommended to add a frequency converter between the inverter and the elevator motor.  

 

(4) The starting power of inductive load is too large.  

 

03  

The solution  

 

The rated power of the load must be lower than that of the inverter, and the peak power of the load cannot be more than 1.5 times of the rated power of the inverter.  

 

 

 

The picture  

Common Problems with Batteries  

 

 

1  

 

Short circuit phenomenon and causes  

 

 

Lead acid battery short circuit refers to the lead acid battery internal positive and negative electrode group connected.  Lead acid battery short circuit is mainly manifested in the following aspects:  

 

 

 

Open circuit voltage is low, the closed circuit voltage (discharge) quickly reaches the stop voltage.  When discharging with high current, the terminal voltage drops rapidly to zero.  When open circuit, electrolyte density is very low, in low temperature environment electrolyte will appear ice phenomenon.  When charging, the voltage rises slowly and remains low (sometimes falling to zero).  When charging, the temperature of the electrolyte rises very high and very quickly.  When charging, electrolyte density rises slowly or hardly changes.  Charging without bubbles or gas appearing very late.  

 

 

 

Causes of lead acid battery internal short circuit mainly include the following aspects:  

 

The diaphragm quality is not good or defective, so that the plate active substance through, resulting in positive and negative plate virtual contact or direct contact.   The partition plate channeling causes the positive and negative plates to be connected.  The active material on the plate expands and falls off. Because the active material deposited too much, the lower edge or side edge of the positive and negative plates contact each other with the sediments, resulting in the positive and negative plates being connected.  A conductive object falls into the battery and connects the positive and negative plates.  

 

 

 

2  

 

Phenomenon and reason of plate acidification  

Plate sulphuric acid is lead sulphate which forms white hard crystals on the plate and is very difficult to convert into active substances when charging.   There are mainly the following phenomena after sulphation of lead-acid battery plate:  

 

 

 

(1) The voltage of lead battery rises rapidly in the charging process, and its initial and final voltage is too high, and the final charging voltage can reach about 2.90V/single cell.  

 

(2) In the discharge process, the voltage drops quickly, that is, prematurely to the termination voltage, so its capacity is significantly lower than other batteries.  

 

(3) When charging, the temperature of the electrolyte rises quickly and easily exceeds 45℃.  

 

(4) When charging, the electrolyte density is lower than normal, and bubbles occur prematurely when charging.  

 

 

 

The main reasons for plate acidification are as follows:  

 

(1) Lead battery initial charge is insufficient or initial charge interruption time is long.  

 

(2) Long-term insufficient charge of lead battery.  

 

(3) Failed to charge in time after discharge.  

 

(4) often excessive discharge or small current deep discharge.  

 

(5) If the electrolyte density is too high or the temperature is too high, lead sulfate will form deeply and it is not easy to recover.  

 

(6) lead-acid battery for a long time, long-term use without regular charging.