The solar controller is called the solar charge-discharge controller, which is used in the solar power generation system to control the multi-path solar cell phalanx to charge the battery and the battery to power the solar inverter.It is the core control part of the whole photovoltaic power supply system.
The most basic function of the solar charge and discharge controller is to control the battery voltage and turn on the circuit. In addition, when the battery voltage rises to a certain level, the battery charge is stopped.The old version of the controller mechanically completes the opening or closing of the control circuit, stopping or starting the power supply to the battery.
The controller is used in most photovoltaic systems to protect the battery from overcharge or overdischarge.Overcharging may vaporize the electrolyte in the battery, causing a fault, while overcharging may cause the battery to fail prematurely.Overcharge and overdischarge 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 Balance System BOS (Balance of System).
In simple terms, the functions of the solar controller can be divided into:
1. Power adjustment function;
2. Communication function: 1. Simple indicating 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, overcurrent, etc.
Solar panels are photovoltaic devices (mainly semiconductor materials), which generate electric current when irradiated by light.Due to the properties and limitations of materials and light, the generated current is also a curve with volatility. If the generated current is directly charged into the battery or directly supplied to the load, it will easily cause damage to the battery and the load, which seriously reduces their life.Therefore, we must first feed the current into the solar controller, digitally adjust it with a series of special chip circuits, and add multistage charge-discharge protection. At the same time, we adopt our unique control technology “adaptive three-stage charging mode (figure 1)” to ensure the operational safety and service life of the battery and the load.When the load is supplied, the current of the battery is first fed into the solar controller, which is adjusted before the current is fed into the load.The purpose of doing so is to stabilize discharge current;The second is to ensure that the battery is not overdischarged;Third, the load and battery can be a series of monitoring protection.
In order to use the ac electrical equipment, the inverter must be added before the load.
1. Single chip microcomputer and special software are used to realize intelligent control;
2. Accurate discharge control using battery discharge rate correction.Discharge terminal voltage is the control point corrected by discharge rate curve, which eliminates the inaccuracy of single voltage control over discharge and conforms to the inherent characteristics of the battery, that is, different discharge rates have different terminal voltage.
3. Full automatic control including overcharge, overdischarge, electronic short circuit, overload protection, and unique anti-reverse connection protection;Above protection does not damage any parts, does not burn insurance;
4. The serial PWM charging main circuit is adopted to reduce the voltage loss of the charging circuit by nearly half compared with the charging circuit using diode, and the charging efficiency is higher than that of non-pwm by 3% to 6%, which increases the power consumption time.Lifting charge after overdischarge recovery, normal direct charge and automatic control of floating charge make the system with longer service life;It also has high precision temperature compensation.
5. Intuitive LED light emitting tube indicates the current status of battery, so that users can understand the use status;
6. All controls are made of industrial-grade chips (only for i-grade controllers), which can operate freely in cold, hot and humid environment.At the same time, crystal timing control is used, and the timing control is accurate.
7. The setting point of potentiometer adjustment control is cancelled, and the working control points are recorded by means of e-square memory, so that the setting is digitized, eliminating the factors that cause the error reduction accuracy and reliability of the control points due to the vibration deviation and temperature drift of the potentiometer.
8. Digital LED display and setting are used. One-click operation can complete all Settings.In places with large temperature difference, qualified controller should also have the function of temperature compensation.Other additional functions such as light switch and time switch should be optional for the controller.
1. Pure light control mode: when there is no sunlight, the light intensity drops to the starting point. After the controller delays for 10 minutes to confirm the start signal, the load is turned on according to the set parameters and the load begins to work.When there is sunlight, the light intensity rises to the starting point. The controller delays for 10 minutes to confirm the closing signal and then closes the output. The load stops working.
2. Light control plus time control mode: the starting process is the same as that of pure light control. When the load works to the set time, it will be automatically closed.
3. Manual mode: in this mode, users can control the opening and closing of load by pressing the button, regardless of whether it is in the day or night.This mode is used for special load situations or for debugging purposes.
4. Debugging mode: it is used for system debugging. When there is light signal, the load is turned off. When there is no light signal, the load is turned on.
5. Normally open mode: the power on load is always in the output state, which is suitable for the load requiring 24-hour power supply.
The popular solar controller in the market mainly includes ordinary solar controller, PWM solar controller and MPPT solar controller.
Ordinary solar controller is the first generation of technology, the principle is the output of the solar panel directly to the port on the battery, when the battery is enough to disconnect, because of the reason of battery internal resistance, it is difficult to put the battery is full, and solar panels are not fully used, charging conversion efficiency is only 70 ~ 76%, has been eliminated by the market, basically very few people use.
The PWM solar controller is the second generation technology, which is the most in the market now. The working mode is the PWM control mode. Compared with the ordinary solar controller, it has made a lot of progress.
MPPT solar controller is the third generation technology, the most high-end solar controller.MPPT solar controller, it is to point to have the maximum power point tracking (MaximumPowerPointTracking) function of the solar controller, is an upgraded version of PWM controller of solar energy, the MPPT solar controller can real-time voltage and current detection of solar panels, and continually track maximum power (P = U * I), the system is always in the most high power for battery charging, the MPPT tracking efficiency is 99%, the whole system power generation high efficiency reached 97%, and the management of the battery with good,It is divided into MPPT charging, constant voltage uniform charging and constant pressure floating charging.With technological progress and energy conservation, the trend of MPPT solar controller replacing traditional PWM solar controller is irreversible.
The new solar controller has the following main functions:
1. Overcharge protection: when the charging voltage is higher than the protection voltage, the battery is automatically turned off to charge. Then, when the voltage drops to the maintenance voltage, the battery enters the floating charge state.
2. Overdischarge protection: when the battery voltage is lower than the protection voltage, the controller automatically closes the output to protect the battery from damage;When the battery is recharged, the power is restored automatically.
3. Load overcurrent and short circuit protection: if the load current exceeds 10A or the load short circuit, the fuse will be blown off, and it can be used again after replacement.
4. Overvoltage protection: when the voltage is too high, the output will be automatically closed to protect the electrical equipment from damage.
5. Anti-charge function: use schottky diode to prevent the battery from charging the solar cell.
6. Anti-lightning function: when lightning strikes, the pressure sensitive resistor can prevent lightning strikes and protect the controller from damage.
7. Solar cell reverse protection: solar cell “+” and “-” polarity reverse connection can be used after correction.
8. Protection of battery reverse connection: battery “+” and “-” polarity connection is reversed, and the fuse is blown off. After replacement, it can be used again
9. Battery opening protection: in case of battery opening, the controller will limit the voltage at both ends of the load when the solar battery is normally charged, so as to guarantee that the load will not be damaged. If the solar battery is not charged at night, the controller will not make any action because it cannot get power.
10. Temperature compensation function.
11. Self-check: when the controller is affected by natural factors or is not operated by people, the controller can be self-checked to let people know whether the controller is intact or not, which reduces many unnecessary hours and creates conditions for winning project quality and duration.
12. Recovery interval: it is the recovery interval for over-charge or over-discharge protection to avoid the work bucket movement caused by line resistance or self-recovery characteristics of battery.
13. Temperature compensation: monitor the temperature of the battery, correct the charge and put value, and make the battery work in the ideal state.
14. Light control: it is mainly used for automatic lamps. When the environment is bright enough, the controller will automatically shut off the load output.When the environment is dark, the load will be automatically turned on to realize the function of automatic control.
Installation and precautions
1. Open the package and fix it in the right place (please avoid direct sunlight and damp places).
2. First connect the battery lead (to make the automatic identification function not wrong), and then connect the solar panel lead after the controller completes the identification process (after the level indicator indicates the battery’s power), and finally connect the load line when the load is off.
3. For the sake of safety, do not overload or overload the solar panels;Replace solar cells with power supplies such as power generators to charge the batteries.
4. When charging, remove the solar panel, and the charging current should not be too large.
4. Pay attention to the positive and negative terminal of the battery.
Common faults and troubleshooting
1. The load does not work
(1) during the day, the controller has light control.
(2) insufficient battery power.
(3) whether the wiring is correct.
(4) remove all the wires, repeat the above installation process, and let the controller re-identify.
You can use it for the first few days, but it won’t work for the next few days
(1) incorrect wiring of solar cells.
(2) solar cells are not well connected.
3. No light control
(1) incorrect wiring of solar cells.
(2) this function is not set, please reset it.
4. Working upon startup, no light control and no time control
(1) this function is not set, please reset it.
(2) the ambient light of solar panels is strong enough.
5. Work instructions are flashing
Short circuit or excessive load.
1, direct charge point voltage: straight charger also called quick charger, belong to the quick charge, typically in the low storage battery voltage large current and relatively high voltage of battery charging, but there is a control point, also called guard point, is the value in the table above, when charging the battery terminal voltage is higher than the protection value, should stop charging.The voltage at the protection point of direct charge is also generally the “overcharge protection point” voltage. When charging, the terminal voltage of the battery cannot be higher than this protection point, otherwise it will cause overcharge and damage to the battery.
2. Charging control point voltage: after direct charging is finished, the battery will generally be static for a period of time by the charging and discharging controller to let its voltage fall naturally. When it falls to the “restoring voltage” value, it will enter the charging state.Why even design?Is when straight after the charge, there may be individual battery “backward” voltage of the (relatively low), in order to bring back these individual molecules, and make all the voltage of the battery has uniform consistency, so will by the high voltage with moderate current charge again for a moment, is the so-called filling, namely “equalizing charge”.All fill time should not be too long, general for a few minutes ~ 10 minutes, time is set too long instead harmful.For a small system with one or two batteries, even charging is of little significance.Therefore, the street lamp controller is generally not set to even charge, only two stages.
3, floating control point voltage: generally is all finished, battery was also stand for a period of time, make its voltage across the natural, when falling to “maintain voltage”, is the state of floating, similar to “trickle charge” (that is, small current charging), low battery voltage on charge, charge it with a little low, the a shares to, in order to avoid the battery temperature rising, this is good for the battery, because the battery internal temperature had a great influence on charging and discharging.In fact, the PWM mode is mainly designed to stabilize the battery terminal voltage and reduce the charging current of the battery by adjusting the pulse width.This is a very scientific charging management system.Specifically, at the later stage of charging and 80% of the remaining capacity (SOC) of the battery, the charging current must be reduced to prevent excessive release of air (oxygen, hydrogen and acid gas) due to overcharging.
4. Over-discharge protection termination voltage: this is easy to understand.The discharge of the battery shall not be lower than this value, which is stipulated by the national standard.Although battery manufacturers also have their own protection parameters (enterprise standards or line standards), but ultimately to close to the national standards.It should be noted that, for safety reasons, the voltage of 12V battery overdischarge protection point is generally artificially added with 0.3v as the temperature compensation or the zero-point drift correction of the control circuit, so that the voltage of 12V battery overdischarge protection point is 11.10v, and the voltage of 24V system overdischarge protection point is 22.20v.
Related to choose
Protect the voltage
Some customers often find that after the solar street lamp is on for a period of time, especially after the continuous cloudy and rainy days, the street lamp will be off for several days or even many days, the battery voltage is also tested normal, and the controller and lamp are not broken.
This problem has puzzled many engineers. In fact, this is the problem of voltage value of “exit from undervoltage protection”. The higher this value is set, the longer the recovery time after undervoltage is set, which makes it impossible to turn on lights for many days.
Due to its own characteristics, LED must be maintained or limited by technical means, otherwise it cannot be used normally.Common LED lights realize constant flow of LED lights by adding another driver power source, but this driver takes up about 10%-20% of the total power of the whole lamp, such as an LED lamp with a theoretical value of 42W, and the actual power may be about 46-50w after driving.When calculating panel power and battery capacity, you must add 10 to 20 percent more to meet the power cost of the drive.In addition to this, the addition of the drive on a more trouble – generating link.The controller has high stability and reduces the total power consumption through the software.
The output time
The ordinary controller can only be set up for a number of hours, such as 4 hours or 8 hours after the lights are turned on, which cannot meet the needs of many customers.The industrial version controller can be divided into three periods, and the time of each period can be set arbitrarily. According to the different use environment, each time period can be set to the closed state.For example, some factories or scenic spots are not occupied at night. They can close the second time slot (late at night) or the second and third time slots (late at night) to reduce the use cost.
The output power
In the solar energy application of the lamps, LED is the most suitable pulse width adjustment to achieve different power output.Control of pulse width or limit current at the same time, the duty cycle of LED lights the whole output adjustment, such as single atom 1 w LED string of 5 and 7 total 35 w leds, discharge at night, late at night and early in the morning time can be separately power regulation, such as the middle of the night to adjust into 15 w, adjustment in the morning as 25 w, and lock current, which can satisfy all night lighting, and saving the cost of the panels, battery configuration.It has been proved by long-term test that LED with pulse width adjustment mode produces much less heat and can extend the service life of LED.
In order to save power at night, some lamp factories make the interior of LED lamp into a 2-way power supply, and turn off the one-way power supply at night to realize the halved output power.
Line loss compensation
Automatic compensation is given according to different diameter and length of wire.Wire loss compensation is actually very important in the low-voltage system, because the voltage is low and the wire loss is relatively large. If there is no corresponding wire loss voltage compensation, the voltage at the output end may be much lower than that at the input end, which will lead to the under-voltage protection of the battery in advance, and the actual application rate of the battery capacity is discounted.It is worth noting that when we use the low-voltage system, in order to reduce the pressure drop of the line loss, we should try not to use too thin cables, and the cables should not be too long.
Many controller in order to reduce cost, without considering the cooling problem, so the larger load current or charging current is larger, the heat increases, the controller of a pipe resistance was increased, a dramatic loss of charging efficiency, service life is greatly reduced after the tube overheating and even destroyed, especially the summer outdoor environment temperature is high, so a good cooling device should be controller is indispensable.
The charging mode of the conventional solar controller is based on the three-stage charging method of the municipal battery charger, namely the three stages of constant current, constant pressure and floating charge.Because of the energy of the mains grid is infinite, without constant current charging, will directly result in battery explosion and damage, but solar panels power of street lamp system is limited, so it survives mains controller of constant current charging method is not scientific, if the panels is greater than the current controller first period of limitation of current, then caused the fall of charging efficiency.The MCT charging method is to track the maximum current of the panel without causing waste. By detecting the voltage of the battery and calculating the temperature compensation value, when the voltage of the battery is close to the peak value, the impulse trickling charging method can not only fill the battery but also prevent the over-charging of the battery.