What is the role of solar controller in solar street light?

Regardless of the size of solar lamps, a charge and discharge control circuit with good performance is essential. In order to prolong the service life of the battery, its charging and discharging conditions must be limited to prevent the battery from being overcharged and deeply discharged. In addition, because the input energy of the solar photovoltaic power generation system is extremely unstable, the control of the battery charging in the photovoltaic power generation system is more complicated than the control of the ordinary battery charging. For the design of solar street lights, success and failure often depend on the success and failure of the charge and discharge control circuit. Without a charge and discharge control circuit with good performance, it is impossible to have a solar street light with good performance.

The special solar controller for solar street lights should mainly have the following functions:

1. Anti-reverse charging control

The function of preventing reverse charging, generally speaking, is to connect a diode in series in the solar cell circuit. The diode prevents reverse charging. This diode should be a Schottky diode, and the voltage drop of the Schottky diode is lower than that of ordinary diodes. In addition, the anti-reverse charging function can also be controlled by a field effect transistor. Its tube voltage drop is lower than that of a Schottky diode, but the control circuit is more complicated than the previous one.

2. Anti-overcharge control

To prevent overcharging, a discharge transistor can be connected in series or in parallel in the input loop, and the voltage discrimination circuit controls the switch of the transistor to discharge excess solar cell energy through the transistor to ensure that there is no excessive voltage to charge the battery. The key is to prevent the selection of overcharge voltage, the single-cell lead-acid battery is 2.2V.



3. Anti-overdischarge control

Except for Ni-Cd batteries, other batteries generally have the function of preventing battery over-discharge, because it will cause permanent damage to the battery over-discharge. It should be noted that the solar cell system generally discharges at a small rate relative to the battery, so the discharge cut-off voltage should not be too low.

4. Temperature compensation

For temperature compensation, the battery voltage control point changes with the ambient temperature, so the solar light system should have a temperature-controlled reference voltage. For a single lead-acid battery, it is -3~-7mV/℃, we usually choose -4mV/℃.