Know about the technical requirements of solar LED lamps?
With the development and advancement of solar photovoltaic technology, solar cells, as a new energy source, were first applied to lighting fixtures for civilian use. Solar lighting products have the dual advantages of environmental protection and energy-saving. Solar LED lighting products are a new generation of green and environmentally friendly lighting products. Its main components include solar photovoltaic cells (PV technology) and semiconductor lighting sources (LED). Because the LED solar lamp integrates the advantages of solar photovoltaic power generation and LED solid-state lighting, the solar LED lighting system realizes the perfect combination of a new generation of energy and a new light source. However, in the design of solar lighting lamps, many factors are involved in the light source, solar battery system, and battery charging and discharging control. Problems in any of these links will cause product defects.
¡¡¡¡1. First understand the composition of solar lamps:
¡¡¡¡The key to the perfect combination of solar photovoltaic power generation technology and LED lighting is that the two are both direct current, low voltage, and compatible with each other. Therefore, the combination of the two does not need to convert the direct current generated by the solar cell into alternating current, thus greatly improving the efficiency of the entire lighting system. At the same time, with the help of grid-connected technology or the use of batteries to charge and discharge energy, its advantages are more obvious.
¡¡1. Solar panels
¡¡¡¡2. Charge and discharge controller
¡¡¡¡5. Lamp shell
¡¡¡¡2. Problems that need to be paid attention to when designing and using: (take LED lawn lamp as an example)
¡¡¡¡1. The characteristics of the LED are close to the stabilized diodes, the working voltage changes between 0 and 1V and the working current may change about 20mA. For safety, the use of series current limiting resistors under normal circumstances, the huge energy loss is obviously not suitable for solar lawn lights, and the LED brightness changes with the operating voltage. It is a good way to use a boost circuit or a simple constant current circuit. In short, the current must be automatically limited, otherwise, the LED will be damaged.
¡¡¡¡2. Generally, the peak current of LED is 50~100mA, and the reverse voltage is about 6V. Be careful not to exceed this limit, especially when the solar battery is reversely connected or the battery is empty, and the peak voltage of the boost circuit is too high, it is likely to exceed this limit and damage LED.
¡¡¡¡3. The temperature characteristic of LED is not good, the temperature rises by 5¡æ, the luminous flux drops by 3%, please pay attention to the use in summer.
¡¡¡¡4. The working voltage is highly discrete. The working voltage of the same model and the same batch of LEDs has a certain difference, so it is not suitable to be used in parallel. Must be used in parallel, should consider current sharing.
¡¡¡¡5. The color temperature of the super bright white LED is 6400k~30000k. At present, ultra-bright white LEDs with low color temperature have not yet entered the market, so solar lawn lights made of ultra-bright white LEDs have a poor penetrating ability, so attention should be paid to optical design.
¡¡¡¡6. Static electricity has a great influence on ultra-bright white LEDs. Anti-static facilities should be provided during installation and workers should wear anti-static wrists. The super bright white LED that is damaged by static electricity may not be visible to the eyes at the time, but the service life will be shortened.
¡¡¡¡7. Pay attention to the light-sensitive sensor in the system combination. Solar lights need light-controlled switches. Some designers often use photoresistors to switch the lights automatically. In fact, the solar cell itself is an excellent light-sensitive sensor. It is a photosensitive switch with better characteristics than photosensitive resistance. The application of solar garden lights is not a big problem, but for solar lawn lights that only use a 1. 2VNi-Cd battery, the solar cell element is composed of four solar cells in series, with low voltage and lower voltage under weak light. Even if there is no dark, the voltage has been lower than 0. 7V, causing the light control switch to fail. In this case, as long as a transistor is directly coupled and amplified, the problem can be solved.
8. The load is controlled according to the voltage of the battery. Solar lamps often require high maintenance time for continuous rainy days, which increases the cost of the system. We reduce the number of LEDs or energy-saving lamps connected when the battery voltage drops on continuous rainy days, or reduce the light-emitting time of solar lamps every day, which reduces the cost of the system.
¡¡¡¡9. Flickering and dimming, gradually brightening and dimming is a good way to save energy. On the one hand, it can increase the illumination effect of solar lawn lights. On the other hand, it can control the average output current of the battery by changing the flicker duty cycle to extend the working time of the system, or Under the same conditions, costs can be reduced.
¡¡¡¡10. The switching speed of the three-color primary color high-efficiency energy-saving lamp. This problem is very important. It even determines the service life of the solar lawn lamp. The three-color primary color high-efficiency energy-saving lamp has a starting current as high as 10-20 times when it is started. The system will cause a large drop in voltage under such a large current. , The solar lawn light can not be started or repeatedly started, resulting in the final damage.
¡¡¡¡11. At present, solar cells cannot be used for main road lighting. The lighting of the main roads of highways has statutory illuminance requirements. As far as the current conversion efficiency and price of solar cells are concerned, this requirement cannot be met. But shortly, with the improvement of technical standards in various aspects, solar cells will definitely be used in the lighting of main highways.
¡¡¡¡12. Regarding energy storage capacitors, the service life of solar batteries is more than 25 years, and the service life of ordinary batteries is 2 to 3 years, so batteries are the weakest link in the solar power system. Energy storage capacitors can solve this problem to a certain extent. The service life of the energy storage capacitor can reach more than 10 years, and the control circuit is simple, but the expensive price limits its application. At present, it is only applied to some traffic lights and decorative lights. With the improvement of technical standards and the decline of product prices, it will be the most promising ideal energy storage component for solar cells.
¡¡¡¡In summary, the solar cell is a huge PN junction, which converts solar energy into electrical energy. LED is another PN junction that can convert electrical energy into light. Its conversion efficiency is constantly improving. I believe it will reach the level of energy-saving lamps shortly, but the service life can reach more than 100.000 hours. This is the real meaning of Greenlighting on the top.