As a new energy source, solar cells are first applied to lighting fixtures in civilian applications. At present, in the western bright project, the application of non-main road solar street lights, solar garden lights and solar lawn lights, solar decorative lights, etc. has gradually formed scale. In the design of solar lighting fixtures, there are many factors involved in the control of the light source, the solar cell system, and the battery charge and discharge. Any problem in any one of the links will cause product defects.
In this paper, the external characteristics of solar cells, battery charge and discharge control, solar lighting fixtures often compare LEDs with three-color high-efficiency energy-saving lamps, analyze their advantages and disadvantages and use occasions. At the same time, an improved method is proposed for the problems existing in the design of solar lamp circuits on the market. Due to its unique advantages, solar lamps have developed rapidly in recent years.
The lawn lamp has low power, mainly for decoration purposes, and has high requirements for mobility. In addition, the circuit is difficult to lay and the waterproof requirement is high. The above requirements make the lawn lamp powered by the solar battery show many unprecedented advantages. Especially in foreign markets, the demand for solar lawn lamps is very large compared to other products. In 2002, only the solar cells consumed by Guangdong and Shenzhen for the manufacture of solar lawn lamps reached 2MW, equivalent to one-third of the domestic solar battery production that year, and this year still maintained a strong development momentum, which was unexpected. Solar garden lights are widely used in parks, living quarters and non-main roads. At the same time, due to the rapid development, some products are not mature enough in technology, there are many defects in the choice of light source and circuit design, which reduces the economy and reliability of the product and wastes a lot of resources. In view of the above problems, this paper puts forward your own views for the reference of factories producing solar lamps.
1) The characteristics of the LED are close to the steady diode, the operating voltage changes by 0.1V, and the operating current may vary by about 20mA. For safety reasons, the use of series current limiting resistors under normal conditions, the great energy loss is clearly not suitable for solar lawn lights, and the brightness of the LED varies with the operating voltage. It is a good idea to use the booster circuit. You can also use a simple constant current circuit. In short, you must automatically limit the current, otherwise the LED will be damaged.
2) The peak current of general LED is 50~100mA, and the reverse voltage is about 6V. Be careful not to exceed this limit, especially when the solar cell is reversed or the battery is unloaded. When the peak voltage of the booster circuit is too high, it is likely to exceed this limit. LED.
3) LED temperature characteristics are not good, the temperature rises by 5 ° C, the luminous flux drops by 3%, and it should be noted in summer.
4) The working voltage is discrete, the same model, the same batch of LED operating voltage has a certain difference, it should not be used in parallel. Must be used in parallel, and should consider current sharing.
5) Super bright white LED color temperature is 6400k~30000k. At present, ultra-bright white LEDs with low color temperature have not yet entered the market, so the solar lawn light produced by ultra-bright white LEDs has relatively poor penetrating power, so attention should be paid to optical design.
6) Static electricity has a great influence on super bright white LEDs. Anti-static facilities should be installed during installation. Workers should wear anti-static wrists. Ultra-bright white LEDs that are damaged by static electricity may not be visible to the eye at the time, but their service life will be shorter.
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