Solar Street Lights: Small Photovoltaic Power Generation System

In today's world of energy shortage and increasingly serious environmental pollution, fully developing and utilizing solar energy is the energy strategy decision of governments around the world for sustainable development. Solar street lights are more and more popular because they do not require special personnel to manage and control, install one-time investment without future electricity expenses, do not need to erect transmission lines or dig trenches to lay cables, and can be easily installed in squares, campuses, parks, streets and other advantages. attach great importance to. The solar street lighting system is usually composed of several parts such as solar cell components, batteries, light sources, controllers (AC light sources also need inverters). Unlike ordinary street lights, solar street lights use solar cells as the only power supply. Because the cost of solar cell components is still relatively high, in order to reduce system costs, efficient light sources must be used. LED is a semiconductor light-emitting device that can convert electrical energy into visible light. In recent years, LED technology has made key breakthroughs, and its cost performance has also been greatly improved. Compared with traditional street light sources, LED light sources have high light efficiency. Close to twice as long as incandescent lamps, with a long life span of more than 105h; traditional light sources consume a lot of power, and most of them work under high pressure. The use of boost inverter links reduces energy utilization, while LEDs use low-voltage DC power supply The safety and low cost of light source control make it possible to adjust the light and shade and to switch frequently. Solar street light systems are generally small photovoltaic systems. The World Bank standard is that the self-consumption current of the small photovoltaic system controller is less than 1% of the rated working current. Therefore, the design of the controller circuit and the selection of low-power devices are very important. The solar street light uses a voltage comparator composed of an integrated operational amplifier as a control circuit. This circuit is a control system composed entirely of hardware, which is simple and reliable, easy to maintain, low in cost, and extremely low in power consumption of the circuit itself. A well-matched circuit. The key of this kind of circuit is to design a better voltage homogeneity according to the charging and discharging characteristics of the battery, and at the same time, the selection of the device must be reliable, coupled with the charging and discharging state indicator circuit composed of light-emitting diodes, it has become a control with practical functions. It has the function of preventing battery over-discharge and over-charging. The system adopts the charging and discharging controller circuit of direct coupling. According to the matching characteristics of the LED and the battery, it can achieve power self-adaptation. In the few months when the solar radiation is insufficient, the charging state of the battery is usually low, and the battery is discharged. The terminal voltage is also lower, so that the load working current is smaller, the power is smaller, and the system can work for a longer time. Conversely, when the solar radiation is sufficient, the load has a larger working current, a larger power, and a brighter load.