With the development and progress of solar photovoltaic technology, solar cells, as a new energy source, are first applied to lighting fixtures in civilian applications. The solar lighting products have the dual advantages of environmental protection and energy conservation. Solar LED lighting products are a new generation of green lighting products. Its main components include solar photovoltaic (PV) and semiconductor lighting (LED). Because the LED solar energy lamp integrates the advantages of solar photovoltaic power generation and LED solid-state lighting solar LED lighting system, to achieve a new generation of energy and the perfect combination of new light sources. However, in the design of solar lighting fixtures, many factors such as light sources, solar battery systems, and control of battery charge and discharge are involved, and any one of these problems may cause product defects.
First, first understand the composition of solar lighting: The key to the perfect combination of solar photovoltaic power generation technology and LED lighting is that both are the same as direct current, low voltage and can match 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, the advantages are even more obvious with the help of grid-connected technology or the use of batteries to store and dissipate energy.
1, solar panels
2, charge and discharge controller
3, battery
4, the load
5, lamp housing
Second, the design needs to pay attention to the problem: (in the case of LED lawn lamp)
1, LED characteristics close to the voltage regulator diode, operating voltage changes 0, 1V, operating current may change about 20mA. In order to be safe, a series limiting resistor is used in normal situations, and the great energy loss is obviously not suitable for solar lawn lamps, and the brightness of the LED varies with the operating voltage. The use of a boost circuit is a good idea. A simple constant current circuit can also be used. In any case, it must be automatically current-limited, otherwise it will damage the LED.
2, the general LED peak current 50 ~ 100mA, reverse voltage of about 6V, be careful not to exceed this limit, especially when the solar battery is reversed or the battery is empty, the boost voltage peak voltage is too high, it is likely to exceed this limit, damage LED.
3, LED temperature characteristics are not good, the temperature rises by 5 °C, luminous flux decreased by 3%, the degree of use in the summer should pay attention.
4. The working voltage has high dispersion, and the same type of LED working voltage in the same batch has a certain difference, which should not be used in parallel. Must be used in parallel, should consider the average flow.
5, super bright white LED color temperature of 6400k ~ 30000k. At present, ultra-high-brightness white LEDs with low color temperatures have not yet entered the market. Therefore, solar lawn lighting made with ultra-bright white LEDs is relatively poor. Therefore, attention must be paid to optical design.
6. Static electricity has a great influence on ultra-bright white LED. When installing, it must have anti-static facilities. Workers should wear anti-static wrists. Ultra-high-brightness white LEDs that are damaged by static electricity may not be visible to the eyes at the time, but their service life will be shorter.
7, the system combination should pay attention to the light sensitive sensor, solar light requires light control switch, and some designers often use light-sensitive resistors to automatically switch the light, in fact, the solar battery itself is an excellent light-sensitive sensor, with It is a photosensitive switch and has better characteristics than a photoresistor. For the application of solar garden lights is not a big problem, but for solar lawn light using only a 1,2VNi-Cd battery, the solar cell element consists of four solar cells in series, the voltage is low, the voltage under low light is lower, As long as no black voltage has fallen below 0, 7V, causing the light-controlled switch to malfunction. In this case, as long as a transistor is directly coupled and amplified, the problem can be solved.
8, according to the battery voltage level control the size of the load, solar lights are often on the continuous rainy days can maintain a high time, which increases the cost of the system. We reduce the number of LEDs or energy-saving lamps to be connected when the battery voltage decreases during continuous rainy days, or reduce the daily light-emitting time of the solar lamp, which reduces the cost of the system.
9, flickering light, lightening darkening is a good way to save energy, on the one hand it can increase the efficiency of solar lawn lighting, on the other hand can change the flashing duty cycle to control the average battery output current, extend the system working time, or in Under the same conditions, the cost can be reduced.
10. The switching speed of three-color base color high-efficiency energy-saving lamps. This problem is very important. It even determines the service life of solar lawn light. The start-up current of up to 10~20 times when the three-color base energy efficient lamp starts, and the system will cause a large drop in voltage when subjected to such a large current. Solar lawn lights cannot start or start repeatedly, resulting in final damage.
11. At present, solar cells cannot be used in main road lighting. Illumination of highway main roads has legal illumination requirements, which cannot satisfy this requirement in terms of current solar cell conversion efficiency and price. However, in the near future with the improvement of technical standards in all aspects, solar cells will be used in the lighting of highway main roads.
12. Regarding the energy storage capacitor, the service life of the solar battery is more than 25 years, and the service life of the common battery is 2 to 3 years. Therefore, the battery is the weakest link in the solar power system. The energy storage capacitor can solve this problem to some 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 energy storage component for solar cells. In summary, a solar cell is a giant PN junction that converts solar energy into electricity. LED is another PN junction that can convert electrical energy into light. Its conversion efficiency is constantly improving. It is believed that the level of energy-saving lamps can be achieved in the near future, but the service life can reach more than 100,000 hours. This is the true meaning. On the green lighting.
