First of all, the issue of the controller is discussed. The cost of the controller in the entire solar street light system is very low, generally between 120 yuan and 200 yuan. Although it looks like an obscure piece, it bears a great deal. The role, if you choose is not good will make the overall system's stability and service life greatly reduced, and a relatively mature controller can also be achieved through the function to reduce the cost of the entire system to achieve the purpose of cost savings.
For the comparison of the above functions, here are some analyses
One: exit protection voltage
Some customers often find that after the solar street light is on for a period of time, especially after continuous rainy days, the street light will be off for several days or even days. The battery voltage is also normal, and the controller and the lamp are all in good condition.
This problem has caused many engineers to doubt, in fact, this is the "exit under voltage protection" voltage value problem, the higher the value is set, the longer the recovery time after the undervoltage, it will cause a lot of days can not be bright light.
For this problem, the industrial version controller allows each customer to set the voltage value for exit protection according to the configuration. But it is worth noting that the configuration of the battery board must be reasonable, if the battery pack's daily charge capacity can not meet the discharge of the night, in the long run, the battery is often in deep discharge, life is greatly shortened, so the battery board configuration must enlarge the margin The greater the configuration of the battery board, the lower the voltage for exiting the protection can be set, so that the battery will not be affected.
Two: LED light constant current output
Due to its own characteristics, LEDs must be subjected to constant current or current limiting through technical means, otherwise they cannot be used normally. The common LED lamp is to realize the constant current to the LED lamp by adding a driving power, but this driver accounts for about 10%-20% of the total lamp power, such as a LED lamp with a theoretical value of 42W. The actual power after driving may be around 46-50W. When calculating the battery power and battery capacity, 10%-20% must be added to meet the power consumption caused by the drive. In addition to that, adding more drivers adds one more link to failure. The industrial version controller has no power consumption and constant current through software and has high stability and reduces overall power consumption.
Three: output period
Ordinary controllers can only be set to turn off after hours or hours, such as 4 hours or 8 hours, which can no longer meet the needs of many customers. The industrial version controller can be divided into 3 periods. The time of each period can be arbitrarily set. According to the use environment, each period can be set to the closed state. For example, some factories or scenic spots may be closed at night, and the second time period (late night) may be closed, or the second and third time periods may be closed to reduce the use cost.
Four: LED lamp output power adjustment
Among the solar energy application lamps, the LED lamp is most suitable for outputting different 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 of 5 and a total of 35W LED lamps are discharged at night, and the power can be separately performed during late night and early morning hours. Adjustment, such as adjusting to 15W late at night, adjusting to 25W in the early morning, and locking the current, so that it can meet the lighting of the night, but also save the configuration cost of the battery board, battery. Through long-term tests, it has been proved that the LED lamp with pulse width adjustment mode generates much less heat, which can prolong the service life of the LED.
Some lamp factories use two power sources inside the LED lamp to achieve power saving at night, and turn off the power source at night to reduce the output power by half. However, it has been proved that this method will only cause half of the light source to be first lighted. Failure, inconsistent brightness, or premature failure of one light source.
V: Line loss compensation
The line loss compensation function is currently difficult for conventional controllers because it requires software settings to automatically compensate for different wire diameters and lengths. Line loss compensation is actually very important in low-voltage systems because the voltage is relatively low and the line loss is relatively large. If there is no corresponding line loss voltage compensation, the output voltage may be lower than the input, which will cause the battery to advance. Undervoltage protection, the actual application rate of battery capacity has been discounted. It is worth noting that when we use low-voltage systems, we should not use cables that are too thin in order to reduce the line-loss voltage drop. The cables should not be too long.
Six: heat dissipation
Many controllers do not consider the problem of heat dissipation in order to reduce costs. In this way, when the load current is large or the charging current is large, the controller increases the field resistance of the controller, resulting in a significant drop in charging efficiency. The service life of the field tube is too high. Greatly reduced or even burned, especially in the summer outdoor environment temperature is high, so a good heat sink should be essential to the controller.
Seven: MCT charging mode
The charging mode of the conventional solar controller is copied from the three-stage charging method of the mains charger, that is, constant current, constant voltage and floating charge. Because the power of the city power grid is infinite, if constant current charging is not performed, it will directly lead to the battery charging and damage. However, the solar panel system has limited battery power. Therefore, the constant current charging method of the continuous use of the mains controller is not Scientifically, if the current generated by the panel is greater than the current limited by the first section of the controller, then the charging efficiency is reduced. The MCT charging method is to track the maximum current of the battery board and does not cause waste. By detecting the battery voltage and calculating the temperature compensation value, when the battery voltage is close to the peak value, pulse-type trickle charging method is adopted, which can not only make the battery full. It also prevents overcharging of the battery.
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