As the world's energy crisis intensifies, countries are seeking solutions to the energy crisis. One way is to seek the use of new and renewable energy; the other is to seek new energy-saving technologies to reduce energy consumption and improve energy efficiency. .
Solar energy is the most direct, universal, and cleanest energy on the planet. As a huge amount of renewable energy, solar energy reaches the surface of the earth every day with approximately 250 million barrels of oil, which can be said to be inexhaustible. exhaust. The spectrum of LEDs is almost entirely concentrated in the visible light band, so the luminous efficiency is high. Most people think that energy-saving lamps can save energy 4/5 is a great initiative, but LEDs also save energy by 1/4, which is greater than solid light sources. reform.
Solar LED lighting integrates the advantages of solar energy and LED.
1. System introduction
1.1 Introduction to the basic composition of the system
The system consists of solar cells
A battery is a device for energy conversion and storage. It reflects chemical energy or physical energy into electrical energy through reflection. A battery is a chemical power source. It is composed of two electrochemically active electrodes with different compositions. The positive and negative poles are immersed in an electrolyte that can provide media conduction. When connected to an external carrier, the internal chemistry is converted. Can provide electricity. The component part (including the bracket), the LED lamp head, the control box (with the controller and battery inside) and the lamp post are composed of several parts; the solar panel light effect reaches 127Wp / m2, the efficiency is high, and it is very beneficial to the wind resistance design of the system; In the lamp head part, 1W white LED and 1W yellow LED are integrated on the printed circuit board and arranged in a lattice with a certain pitch as a plane light source.
The control box body is made of stainless steel, which is beautiful and durable; the maintenance-free lead-acid battery and charge and discharge controller are placed in the control box. The system uses a valve-regulated sealed lead-acid battery. Because of its low maintenance, it is also called a "maintenance-free battery", which is conducive to the reduction of system maintenance costs. The charge and discharge controller is designed with complete functions (with light Control, time control, over-charge protection, over-discharge protection and reverse connection protection, etc.) and cost control to achieve a high cost performance.
1.2 Introduction to working principle
The working principle of the system is simple. The solar cell made by the principle of photovoltaic effect receives solar radiation energy during the day and converts it into electrical energy output. It is stored in the battery through the charge and discharge controller, and the illumination gradually decreases to about 101ux at night. The open circuit voltage of the board is about 4.5V, the charge and discharge controller detects this voltage value, and the battery discharges the lamp head. After the battery has been discharged for 8.5 hours, the charge-discharge controller operates and the battery discharge ends. The main function of the charge and discharge controller is to protect the battery. [next]
2. System design ideas
Compared with general solar lighting, the design of solar street lights has the same basic principles, but there are more links to be considered. The following will take Hong Kong Zhenmingli Group Co., Ltd.'s solar LED high-power street lamp as an example to analyze in several aspects.
2.1 Selection of solar cell modules
Design requirements: Guangzhou area, load input voltage 24V power consumption 34.5W, working hours 8.5H per day, to ensure continuous rainy days for 7 days.
(1) The average annual radiation in Guangzhou area is 107.7Kcal / cm2 in the past two decades. After a simple calculation, the peak sunshine hours in Guangzhou area is about 3.424H;
⑵ Daily power consumption of load = 12.2AH
⑶Total charging current of solar modules required = 1.05 × 12.2 × ÷ (3.424 × 0.85) = 5.9A
Here, the shortest number of days between two consecutive rainy days is 20 days, 1.05 is the comprehensive loss factor of the solar cell module system, and 0.85 is the battery charging efficiency.
⑷Minimum total power of solar modules = 17.2 × 5.c = 102W
The use of standard battery components with a peak output power of 110Wp and a single 55Wp should ensure the normal operation of the street light system in most cases of the year.
2.2 Battery selection
Calculation of battery design capacity is simpler than the peak wattage of solar modules.
According to the above calculation, the daily power consumption of the load is 12.2AH. When the battery is full, you can work continuously for 7 rainy days, plus the work of the first night, the battery capacity:
12.2 × (7 + 1) = 97.6 (AH), choose 2 sets of 12V100AH ​​batteries can meet the requirements.
2.3 Solar cell module bracket
2.3.1 Inclination design
In order to make the solar cell modules receive as much solar radiation energy as possible in a year, we have to choose an optimal tilt angle for the solar cell modules.
Discussions on the optimal tilt angle of solar cell modules have appeared in a number of academic journals in recent years. This street lamp is used in the Guangzhou area. According to the data in the relevant literature [1] for this design, the tilt angle of the selected solar cell module bracket is 16 degrees.
2.3.2 Wind resistance design
In the solar street light system, a structural problem that needs to be paid attention to is wind resistance design. The wind resistance design is mainly divided into two major parts, one is the wind resistance design of the battery assembly bracket, and the other is the wind resistance design of the lamp post. The following analysis is made separately according to the above two.
â‘´Wind resistance design of solar cell module bracket
According to the technical parameter data of battery module manufacturers, the solar cell module can withstand upwind pressure of 2700pA. If the wind resistance coefficient is selected to be 27M / s (equivalent to a ten-level typhoon), according to non-viscous fluid mechanics, the wind pressure on the battery module is only 365pA. Therefore, the component itself can withstand 27M / s wind speed without damage. Therefore, the key consideration in the design is the connection between the battery assembly bracket and the lamp post.
In the design of the street lamp system, the connection design of the battery assembly bracket and the lamp post is fixedly connected by a bolt rod.
⑵Windproof design of street lamppost
The parameters of the street lamp are as follows:
Panel tilt angle A = 16 ° pole height = 5M
The design selects the width of the welding seam at the bottom of the lamp post δ = 4MM and the outer diameter of the bottom of the lamp post = 168MM
The surface of the welding seam is the destruction surface of the lamp post. The distance from the calculation point p of the resistance moment W of the lamp pole to the action line of the panel load F received by the lamp pole is pQ = [5000+ (168 + 6) / tAn16 °] × Sin16 ° = 1545MM = 1.545M. Therefore, the acting moment of wind load on the destruction surface of the lamp pole M = F × 1.545.
According to the design maximum allowable wind speed of 27M / s, the basic load of the 2 × 30W dual-lamp solar street light panel is 730N. Considering the safety factor of 1.3, F = 1.3 × 730 = 949N.
Therefore, M = F × 1.545 = 949 × 1.545 = 1466N.m.
According to the mathematical derivation, the resistance moment of the circular failure surface W = π × (3r2δ + 3rδ2 + δ3).
In the above formula, r is the inner diameter of the ring and δ is the width of the ring.
Resistance moment of failure surface W = π × (3r2δ + 3rδ2 + δ3) = π × (3 × 842 × 4 + 3 × 84 × 42 + 43) = 88768mm3
= 88.768 × 10-6m3
Stress caused by wind load acting on the failure surface = M / W = 1466 / (88.768 × 10-6) = 16.5 × 106pA = 16.5MpA << 215MpA
Among them, 215MpA is the bending strength of Q235 steel.
Therefore, the width of the weld selected by the design meets the requirements. As long as the welding quality can be guaranteed, the wind resistance of the lamp post is no problem.
2.4 Controller
The main function of the solar charge and discharge controller is to protect the battery. The basic functions must have overcharge protection, overdischarge protection, light control, time control and anti-reverse connection.
The general parameters of the battery over-protection and over-discharge protection voltage are shown in Table 1. When the battery voltage reaches the set value, the state of the circuit is changed.
In the selection of devices, there are currently one-chip computers and some comparators. There are many schemes, each with its own characteristics and advantages. The corresponding scheme should be selected according to the needs and characteristics of the customer group, which will not be elaborated here.
2.5 Surface treatment
This series of products adopts new technology of electrostatic coating and mainly uses Fp professional building material coatings. It can meet the customers' requirements for the consistent color and environment of the product surface. At the same time, the product has high self-cleaning, strong corrosion resistance and aging resistance. It is suitable for any Climate environment. The processing technology is designed to be coated on the basis of hot-dip zinc, which greatly improves the performance of the product and reaches the strictest AAMA2605.2005 requirements. Other indicators have reached or exceeded the relevant requirements of GB. [next]
3. Conclusion
The overall design basically considers all links; the peak wattage selection design of photovoltaic modules and the selection of battery capacity adopt the most common design method at present, and the design ideas are more scientific; the wind resistance design consists of two components: the battery module bracket and the light pole The analysis is done and the analysis is more comprehensive; the surface treatment adopts the most advanced technology at present; the overall structure of the street lamp is simple and beautiful; and the actual operation proves that the matching between the various links is good.
At present, the initial investment problem of solar LED lighting is still a major problem that puzzles us. However, the solar cell light efficiency is gradually increasing, and the price will gradually decrease. Similarly, the LED light efficiency in the market is rapidly increasing, but the price is decreasing. Compared with the renewable energy of solar energy, clean and pollution-free, and environmental protection and energy-saving of LED, conventional fossil energy is becoming increasingly tense, and will cause increasingly serious pollution to the environment after use. Therefore, solar LED lighting, as an ascending outdoor lighting, will show us infinite vitality and broad prospects.
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