Faced with the reality that the earth's ecological environment is deteriorating and resources are increasingly scarce, governments around the world have adopted many policies and measures to support and develop energy-saving and environmental protection industries. Solar LED street lamps are a comprehensive application of solar energy development and energy-saving technologies in the field of lighting. According to statistics, lighting consumption accounts for about 20% of the total electricity consumption. Reducing lighting power is an important way to save energy. Solar energy is clean, environmentally friendly and renewable, and LED lighting is currently the most in the world. Advanced lighting technology is the fourth generation light source after incandescent lamp, fluorescent lamp and high-intensity gas discharge lamp. It has simple structure, high efficiency, light weight, good safety performance, no pollution, maintenance-free and long life, controllable performance. Strong features are considered to be the best way to achieve energy saving in the field of lighting. There are statistics showing that only LED street lights can save energy for China by saving about one dam from the Three Gorges Dam every year. Due to the energy saving and environmental advantages of LED lighting fixtures, its global output has increased in recent years.
The solar LED street lamp controller designed in this paper firstly detects the solar cell output and battery power and other parameters to determine the system working state, and uses the maximum power point tracking MPPT algorithm to achieve maximum energy collection. After the energy storage is completed, the PWM technology is utilized. Adjusting the brightness of the LED to further save energy, thus realizing the automatic control and intelligent energy management of the whole system, and is more conducive to the application and promotion of solar street lamps.
1 Introduction to Solar LED Street Light System
1. 1 The composition of the solar LED street light system
The Solar Street Light system consists of the following parts: solar panels, LED lamps (including LED light source, pole and lamp housing), controller, battery pack, as shown in Figure 1.
1. 2 Basic Principles of Solar LED Street Light System
The Solar Panel made by the photovoltaic effect principle receives solar radiation energy and converts it into electric energy output during the day, and is stored in the battery through the charge and discharge controller; when the illumination is gradually reduced at night, the charge and discharge controller detects this change, and the battery starts. Discharge the LED street light. After the battery is discharged for about 10 hours, the charge and discharge controller operates and the battery discharge ends.
According to the sunshine characteristics of Hainan Sanya and the design standards of urban road lighting , the components of the system are as follows: LED street light 1 group (32 W, 24 V, 1.4 A; LED 1 W light source; 4 groups in parallel, each group 8 series); 2 solar panels (each group rated output voltage 18 V, operating current is 5. 6 A, open circuit voltage is 21. 2 V, short circuit current is 6. 1 A, peak power is 80 W); Battery (12 V, 200 Ah; overcharge voltage 14.8 V, float voltage 12.3 V, over discharge voltage 10. 8 V).