The solar street lamp realizes the effect of night lighting by converting solar energy into electric energy and storing it. At night, the solar LED lamp is powered by the battery to bring light to pedestrians and vehicles at night.
An important component to realize this function is the solar street lamp controller. The common solar street lamp controllers are in the form of PWM and MPPT. Today, let’s introduce the advantages and disadvantages of MPPT controllers.
MPPT controller is also called maximum power point tracking mode controller. This controller is the mainstream solar street lamp controller at present. The circuit is more complex and the cost is a little higher. The price is generally ten times that of PWM controller. The cheaper ones are several times more.
The biggest feature of MPPT controller is that it can obtain the maximum energy from the solar panel by adjusting the voltage, and then the MPPT controller converts it into the charging voltage required by the lithium battery to supply power to the battery.
When the MPPT solar street lamp controller cuts off the direct connection between the PWM controlled solar panel and the lithium battery, keep the solar panel charging the low-voltage lithium battery at a higher voltage so that the charging is faster and more efficient.
MPPT solar street lamp controller is divided into three stages: current limiting charging, constant voltage equalizing charging, and constant voltage floating charging.
In the current limiting charging stage of MPPT controller, the lithium battery voltage is relatively low. MPPT supplies the maximum output of solar energy to the lithium battery. The stronger the illumination, the greater the charging current.
When the threshold is reached, the yellow diamond will be directly replaced with constant current charging. If the illumination intensity becomes weak, it will immediately switch to the charging mode
Constant voltage equalizing charging mode. When the lithium battery is under the control of MPPT, whether through fast charging or constant current charging mode, when the lithium battery reaches the saturation voltage, it will enter the constant voltage average charging mode.
At this time, the charging current will slowly decrease. When it reaches 0.01c, the constant voltage average charging mode will terminate and enter the floating charging stage.
In the constant voltage floating charging stage, the MPPT controller will charge the lithium battery at a voltage slightly lower than the constant voltage charging. This stage is mainly to supplement the power consumed by the lithium battery’s own sub-store so that the lithium battery can enter a fully saturated battery capacity state when using the stored power.
Unlike the PWM controller, the MPPT controller has the maximum power tracking function. Before the power is saturated, the solar panel can maintain the maximum power output during charging, and the temperature has little impact on the MPPT controller, and the charging efficiency is higher than that of the PWM controller.
Unlike the PWM controller, the MPPT controller intelligently matches and uses the relevant voltage system. The solar street lamp system corresponding to the MPPT controller is more extensive.
For example, the voltage of the solar panel can be used between 12v-170v, and the voltage of the battery can be adjusted between 12-96v. It has wider applicability and a more flexible and convenient component configuration.
