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Solar street light charge controller and discharge controller

2021-07-14 14:47:58

Solar street light charge controller and discharge controller 1

 

Solar Street Light Controller


The full name of the solar street light controller is the solar charge and discharge controller. It is an automatic control device used in the solar street light power generation system to control the multi-channel solar cell array to charge the battery and the battery to supply power to the solar inverter load. It regulates and controls the charging and discharging conditions of the battery, and controls the power output of the solar cell components and the battery to the load in accordance with the power demand of the load. It is the core control part of the entire photovoltaic power supply system.
 
Full name: solar street light charge and discharge controller
Application system: solar street light power generation system

Introduction
The solar light control system is composed of solar panels, battery controllers, and loads.

The solar light controller is a device used to control the photovoltaic panel to charge the battery and provide the load control voltage for the voltage-sensitive equipment. It regulates and controls the charging and discharging conditions of the battery, and controls the power output of the solar cell components and the battery to the load in accordance with the power demand of the load. It is the core control part of the entire photovoltaic power supply system. It is specially designed for the power supply system of communication or monitoring equipment in remote areas. The controller's charge control and load control voltages are fully adjustable and can display battery voltage, load voltage, solar array voltage, charging current, and load current.

Almost all solar power generation systems powered by batteries require a solar light charge and discharge controller. The role of the solar light charge and discharge controller is to adjust the power, the power delivered from the solar panel to the battery. Overcharge of the battery will at least significantly reduce the battery life, from the worst to damage the battery until it cannot be used normally.

The solar light controller uses a high-speed CPU microprocessor and a high-precision A/D analog-to-digital converter. It is a microcomputer data acquisition and detection control system. It can quickly collect the current working status of the photovoltaic system in real-time, obtain the working information of the PV station at any time, and accumulate the historical data of the PV station in detail, which provides accurate and accurate evaluation for the rationality of the PV system design and the reliability of the quality of the inspection system components. Sufficient basis. In addition, the solar controller also has a serial communication data transmission function, which can centrally manage and remotely control multiple photovoltaic system sub-stations.

Solar street light charge controllers usually have 6 nominal voltage levels: 12V, 24V, 48V, 110V, 220V, 600V

At present, the solar street light charge controller is developed from multi-functions, and there is a trend to integrate the traditional control part of the inverter and the detection system.

Effect
The most basic function of the solar charge and discharge controller is to control the battery voltage and open the circuit, and stop the battery charging when the battery voltage rises to a certain level. The old version of the controller mechanically completes the opening or closing of the control circuit, stopping or starting the power delivered to the battery by the power supply.

In most photovoltaic systems, a controller is used to protect the battery from overcharging or over-discharging. Overcharging may vaporize the electrolyte in the battery and cause malfunctions, while over-discharging the battery may cause premature battery failure. Overcharge and over-discharge may damage the load. Therefore, the controller is one of the core components of the photovoltaic power generation system and the main part of the BOS (Balance of System).
Simply put, the functions of the solar light controller can be divided into:
1 Power adjustment function;
2 Communication function: 1 Simple indication function 2 Protocol communication function such as RS485 Ethernet, wireless and other forms of background management;
3 Perfect protection function: electrical protection reverse connection, short circuit, over current, etc.

Solar panels are photovoltaic devices (the main part is semiconductor materials). After being irradiated by light, the photovoltaic effect generates electric current. Due to the properties and limitations of materials and light, the generated current is also a volatile curve. If the generated current is directly charged into the battery or directly supplies power to the load, it will easily cause damage to the battery and the load. Reduced their lifespan. Therefore, we must first send the current to the solar controller, use a series of dedicated chip circuits to digitally adjust it, add multi-level charge and discharge protection, and use our company’s unique control technology "adaptive three-stage charging mode". Ensure the operational safety and service life of the battery and load. When supplying power to the load, the current of the battery is also allowed to flow into the solar controller first, and after its adjustment, the current is sent to the load. The purpose of this is: one is to stabilize the discharge current; the other is to ensure that the battery is not over-discharged; the third is to carry out a series of detection and protection on the load and the battery.

If you want to use AC power equipment, you also need to add an inverter before the load to convert to AC.

Main feature
1 Using a single-chip microcomputer and special software to realize intelligent control;
2 Accurate discharge control using battery discharge rate characteristic correction. The end-of-discharge voltage is the control point corrected by the discharge rate curve, which eliminates the inaccuracy of the over-discharge of simple voltage control, and conforms to the inherent characteristics of the battery, that is, different discharge rates have different end voltages;
3 With automatic control such as overcharge, over-discharge, electronic short circuit, overload protection, and unique anti-reverse connection protection; none of the above protections will damage any parts, and many insurances;
4 The series PWM charging the main circuit is adopted, which reduces the voltage loss of the charging circuit by nearly half compared with the charging circuit using diodes, and the charging efficiency is 3% to 6% higher than that of non-PWM, which increases the power consumption time; the over-discharge recovery improves the charging, The normal direct charge and float charge automatic control system have a longer service life; at the same time, it has high-precision temperature compensation;
5 The intuitive LED luminous tube indicates the current battery status, allowing users to understand the usage status;
6 All controls use industrial-grade chips, which can run freely in cold, high temperature, and humid environments. At the same time, the crystal oscillator timing control is used, and the timing control is accurate;
7 The digital LED display and settings are used, and all settings can be completed by a one-button operation. The extremely convenient and intuitive use is to control the working status of the entire system and to protect the battery from overcharge and over-discharge. In places with large temperature differences, a qualified controller should also have the function of temperature compensation. Other additional functions such as light control switch and time control switch should be optional options of the controller.

Mode
1 Pure light control mode: when there is no sunlight, the light intensity drops to the start point, after the controller confirms the start signal after a delay of 5 seconds, the load is turned on according to the set parameters, and the load starts to work; when there is sunlight, the light intensity rises to start Point, the controller delays for 5 seconds to confirm the shutdown signal and then turns off the output, and the load stops working.
2 Light control plus time control mode: the start-up process is the same as pure light control, when the load is working to the set time, it will automatically turn off, and the set time is 1 to 14 hours.
3 Manual mode: In this mode, the user can control the opening and closing of the load by pressing the buttons, regardless of whether it is during the day or at night. This mode is used for some special load occasions or during debugging.
4 Debugging mode: used for system debugging. When there is a light signal, the load is turned off, and the load is turned on without a light signal, which is convenient for checking the correctness of the system installation during installation and debugging.
5 Normally open mode: The load always keeps the output state after power-on. This mode is suitable for loads that require 24 hours of power supply.

Classification
The popular solar light charge controllers on the market mainly include ordinary solar light controllers, PWM solar charge controllers, and MPPT solar charge controllers.

Ordinary solar charge controller is the first-generation technology. The working principle is to directly connect the output of the solar panel to the battery port, and disconnect it when the battery is full. It is difficult to fully charge the battery due to the internal resistance of the battery, and the solar panel It has not been fully utilized, and the charging conversion efficiency is only 70 to 76%, which has been eliminated by the market, and basically few people use it.

The PWM solar controller is the second-generation technology, and it is the most on the market now. The working mode is PWM control mode (pulse width modulation is an analog control mode, which modulates the bias of the transistor base or the MOS gate according to the corresponding load changes. Set, to realize the change of transistor or MOS tube conduction time, so as to realize the change of the output of the switching regulated power supply. This method can keep the output voltage of the power supply constant when the working conditions change. It uses the digital signal of the microprocessor to be A very effective technology for analog circuit control. It is widely used in many fields from measurement communication to power control and conversion). Compared with ordinary solar controllers, it has improved a lot. It can solve the problem of battery dissatisfaction and charge conversion efficiency. 75 to 80%, but the solar panels are not fully utilized.

MPPT solar controller is the third generation technology, the most high-end solar controller. The MPPT solar controller refers to the solar controller with the function of "maximum power point tracking". It is an upgraded product of the PWM solar controller. The MPPT solar controller can detect the voltage and current of the solar panel in real-time, and continuously track the maximum power so that The system always charges the battery with the maximum power. The MPPT tracking efficiency is 99%, and the power generation efficiency of the entire system is as high as 97%. It also has excellent management of the battery, which is divided into MPPT charging constant tooth charging and constant tooth floating charging. With the advancement of technology and energy conservation, the trend of MPPT solar controllers replacing traditional PWM solar controllers is irreversible

Features
The new solar controller has the following main functions:
1 Overcharge protection: When the charging voltage is higher than the protection voltage, the battery will be automatically turned off to charge the battery. After that, when the voltage drops to the maintenance voltage, the battery will enter the floating charge state. When the voltage is lower than the recovery voltage, the float charge will be turned off and enter the equalized charge state.
2 Over-discharge protection: When the battery voltage is lower than the protection voltage, the controller automatically turns off the output to protect the battery from damage; when the battery is recharged, it can automatically restore power.
3 Load over-current and short-circuit protection: After the load current exceeds 10A or the load is short-circuited, the fuse is blown, and it can be used after replacement
4 Overvoltage protection: When the voltage is too high, the output is automatically turned off to protect the electrical appliances from damage.
5 With anti-reverse charging function: Schottky diodes are used to prevent the storage battery from charging the solar battery.
6 With lightning protection function: when there is a lightning strike, the varistor can prevent lightning strikes and protect the controller from damage.
7 Solar battery reverse connection protection: solar battery "+" and "-" polarity connection is reversed, it can continue to be used after correction
8 Battery reverse connection protection: the battery "+" and "-" polarity is reversed, the fuse is blown, and it can be used after replacement
9 Battery open circuit protection: In case the battery is open circuit, if the solar battery is charging normally, the controller will limit the voltage at both ends of the load to protect the load from being damaged. If it is at night or when the solar battery is not charging, the controller will not be able to get it. When it comes to power, there will be no action.
10 With temperature compensation function.
11 Self-check: When the controller is affected by natural factors or thinks that the operation is improper, you can let the controller self-check to let people know whether the controller is in good condition, reducing a lot of unnecessary man-hours, and creating conditions for winning the quality of the project and the construction period. .
12 Recovery interval: It is the recovery interval for overcharge or overdischarge protection to avoid resistance or the self-recovery characteristics of the battery from causing the load to move.
13 Temperature compensation: monitor the temperature of the battery, make corrections to the charge and discharge values, and make the battery work in an ideal state.
14 Light control: It is mostly used for electric lamps. When the environment is bright enough, the controller will automatically turn off the load output; and when the environment is dark, it will turn on the load to realize the automatic control function.

 

Solar street light charge controller and discharge controller 2


Installation and precautions
1 Open the package and fix it in a suitable place (please avoid direct sunlight and humid places)
2 First connect the battery lead (in order to prevent errors in the automatic identification function), and wait for the controller to complete the identification process (after the level indicator shows the battery power), then connect the solar panel lead, and finally when the load is turned off Connect the load line below.
3 In order to use safety, do not use excessive load or increase the solar panel too large; use a power supply such as a power supply to replace the solar battery to charge the battery.
4 When charging, remove the solar panel, and the charging current should not be too high.
5 Pay attention to the polarity of the battery.

Common faults and troubleshooting
1 The load is not working (the light is off)
(1) During the day, the controller has light control
(2) Insufficient power in the battery
(3) Whether the wiring is correct
(4) Remove all wires, repeat the above installation process, let the controller re-identify
2 It can be used in the first few days but will not work after a few days
(1) The solar cell wiring is incorrect
(2) The solar cell is not connected properly
3 Can not be controlled by light
(1) The solar cell wiring is incorrect
(2) This function is not set, please reset
4 It works when it is turned on, and it cannot be controlled by light or time.
(1) This function is not set, please reset
(2) The ambient light of the solar panel is strong enough
5 The work instruction flashes non-stop
(1) The load is short-circuited or the load is too large

Protection mode
1. Direct charge protection point voltage: Direct charge is also called emergency charge, which belongs to fast charging. Generally, the battery is charged with high current and relatively high voltage when the battery voltage is low. However, there is a control point, also called protection point. , Is the value in the above table. When the battery terminal voltage is higher than these protection values ​​during charging, the direct charging should be stopped. The voltage of the direct charge protection point is generally the "overcharge protection point" voltage, and the battery terminal voltage cannot be higher than this protection point during charging, otherwise it will cause overcharge and damage the battery.

2. Voltage at the equalization control point: After the direct charge is over, the battery will generally be allowed to stand still for a period of time by the charge and discharge controller to allow its voltage to drop naturally. When it drops to the "recovery voltage" value, it will enter the equalization state. Why design equalization? That is, after the direct charge is completed, there may be individual batteries "lag behind" (the terminal voltage is relatively low). In order to pull these individual molecules back and make all the battery terminal voltages uniform, it is necessary to match the high voltage with a moderate If the current is recharged for a short while, it can be seen that the so-called equal charge, which is "equal charge". The equalization time should not be too long, usually a few minutes to ten minutes, setting the time too long is harmful. For a small system equipped with a two-cell battery, equal charging is of little significance. Therefore, street light controllers generally do not have equal charging, and only have two stages.

3. Floating charge control point voltage: Generally, after the equalizing charge is completed, the battery is also left to stand for a period of time to make its terminal voltage drop naturally. When it drops to the "maintenance voltage" point, it enters a floating charge state, similar to "trickle current". "Charge". When the battery voltage is low, charge a little, and charge a little when the battery voltage is low, so that the battery temperature will not continue to rise. This is for the battery.

 

It is very beneficial, because the internal temperature of the battery has a great influence on charging and discharging. In fact, the PWM method is mainly designed to stabilize the battery terminal voltage and reduce the battery charging current by adjusting the pulse width. This is a very scientific charging management system. Specifically, in the later stage of charging, when the remaining capacity (SOC) of the battery is> 80%, the charging current must be reduced to prevent excessive outgassing (oxygen, hydrogen, and acid gas) due to overcharging.

4. Over-discharge protection termination voltage: This is easier to understand. The battery discharge cannot be lower than this value, which is the stipulation of the national standard. Although battery manufacturers have their own protection parameters, they still have to move closer to the national standard. It should be noted that, for safety reasons, the over-discharge protection point voltage of the 12V battery is generally added to 0.3V as temperature compensation or the zero drift correction of the control circuit, so that the over-discharge protection point voltage of the 12V battery is 11.10V, then The over-discharge protection point voltage of the 24V system is 22.20V

 

Solar street light charge controller and discharge controller 3


Related options
Protection voltage
Some customers often find that after the solar street lamp is on for a period of time, especially after continuous rainy days, the street lamp will not be on for several days or even many days, the voltage of the battery is normal, and the controller and the lamp are not faulty.

This problem has puzzled many engineering companies. In fact, this is a problem of the voltage value of “exit under-voltage protection”. The higher the value is set, the longer the recovery time after under-voltage is, and it will not be able to light up for many days. light.

Current output
Due to its own characteristics, the LED must be constant current or current limited by technical means, otherwise, it cannot be used normally. Common LED lights are achieved by adding a driving power supply to achieve constant current to the LED lights, but this drive accounts for about 10% to 20% of the total power of the entire lamp, such as an LED lamp with a theoretical value of 42W, plus The actual power after driving maybe around 46~50W. When calculating the power of the panel and the capacity of the battery, an additional 10% to 20% must be added to meet the power consumption caused by the drive. In addition to this, adding more drivers will add another link to cause failures. The industrial version of the controller uses software to perform a constant current without power consumption, with high stability and lower overall power consumption.

Output period
Ordinary controllers generally can only be placed 4 hours or 8 hours after turning on the lights and waiting for several hours to turn off, which has been unable to meet the needs of many customers. The industrial version of the controller can be divided into 3 periods, the time of each period can be set arbitrarily, according to the different use environment, each period can be set to the off state. For example, if there are no people in some factories or scenic areas at night, you can close the second period (late night), or close both the second and third periods, to reduce the cost of use.

Output Power
Among solar-powered lamps, LED lamps are the most suitable for achieving different output power through pulse width adjustment. While limiting the pulse width or limiting the current, the duty cycle of the entire output of the LED lamp is adjusted. For example, a single 1W LED7 string 5 and a total of 35W LED lamps can be discharged at night, and the late night and early morning periods can be separately power Adjustment, such as adjusting to 15W in the middle of the night, 25W in the early morning, and locking the current, so as to satisfy the lighting all night, and save the cost of battery board and battery configuration. Long-term experiments have proved that the pulse width adjustment method of the LED lamp generates much less heat in the whole lamp, which can prolong the service life of the LED.

In order to save power at night, some lamp farms make the internal LED lights into two power sources, and turn off one power source at night to achieve half of the output power. However, practice has proved that this method will only cause half of the light source to light up first. Attenuation, inconsistent brightness, or premature damage to a light source.

Line loss compensation
According to different wire diameters and wire lengths, automatic compensation is provided. Line loss compensation is actually very important in low-voltage systems, because the voltage is low and the line loss is relatively large. If there is no corresponding line loss voltage compensation, the voltage at the output terminal may be much lower than the input terminal, which will cause the battery to advance. Under voltage protection, the actual application rate of battery capacity is discounted. It is worth noting that when we use a low-voltage system, in order to reduce the line loss and voltage drop, try not to use too thin cables, and the cables should not be too long.

Heat dissipation
In order to reduce costs, many controllers do not consider the issue of heat dissipation. When the load current is large or the charging current is large, the heat increases and the internal resistance of the controller is increased, resulting in a significant decrease in the charging efficiency and the service life of the venue after overheating. Greatly reduce or even be burned, especially the outdoor environment temperature in summer is very high, so a good heat dissipation device should be indispensable for the controller.

Charging mode
The charging mode of the conventional solar controller is to copy the three-stage charging method of the mains charger, namely the three stages of constant current and constant voltage and floating charge. Because the energy of the mains power grid is infinite, if the constant current charging is not carried out, it will directly cause the battery to explode and damage, but the solar street lamp system has limited battery power, so it is not necessary to continue to use the constant current charging method of the mains controller. Scientifically, if the current generated by the battery panel is greater than the current limited by the first stage of the controller, it will cause a drop in charging efficiency. The MCT charging method is to track the maximum current of the battery board without causing waste. By detecting the battery voltage and calculating the temperature compensation value, when the battery voltage is close to the peak value, the pulse-type trickle charging method is adopted to fully charge the battery. It also prevents overcharging of the battery.

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