Among electric light sources, the most ideal light source for solar photovoltaic lighting in the future should be LED.
In recent years, due to the rapid development of LED technology and the global energy shortage, the concept of “semiconductor green lighting” has been accepted by more and more people. In 2004, the National Semiconductor Lighting Project Coordination Leading Group was announced. The Ministry of Science and Technology, together with the Ministry of Information Industry, the Ministry of Construction, the Ministry of Education, the China National Light Industry Council, and the Chinese Academy of Sciences, began to jointly launch the semiconductor lighting project. Internationally, General Electric, Philips, and Osram have combined with semiconductor companies to establish semiconductor lighting companies. “Laser World” in the United States once wrote that white LEDs will account for more than 25% of the lighting market by 2025. Industry insiders have reported abroad that semiconductor lamps will replace 20% of incandescent lamps. This estimate may be optimistic, but it reveals the future application prospects and growth potential of semiconductor lamps. According to statistics, if 25% of the incandescent lamps and all fluorescent lamps in Taiwan are replaced by white LEDs, 11 billion kilowatt-hours of electricity can be saved each year, which is equivalent to the power supply capacity of a nuclear power plant. Since lighting consumption accounts for 20% of the entire power consumption, the world’s annual energy savings by using this light source reaches 100 billion US dollars. Therefore, vigorously developing white light LED technology will be an effective way to protect the environment and save energy. In the next two decades, the use of solid-state lighting will reduce the world’s electricity consumption for lighting by 50% and save 10% of global electricity consumption.
It is estimated that in 10 years, more than half of the electricity used for lighting may come from solar energy. Among human power generation technologies, solar photovoltaic power generation is a technology that can provide electricity without any pollution. As we all know, 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 energy. Its conversion efficiency is improving day by day. It is said that it will soon reach the level of energy-saving lamps, and the service life can reach more than 100,000 hours. This kind of PN junction- The lighting of the PN junction is the real green lighting.
The popularity of solar cells and the advancement of LED lighting technology enable people to stand at another height to examine what is the real green lighting for humans in the future. The most promising green lighting system in the future should be: solar cell light-emitting diodes, that is, a PN junction-PN junction semiconductor green lighting system. It has the unmatched advantages of any lighting system in the world: clean, no pollution, high efficiency and long life. Their combination should have two kinds of independent semiconductor green lighting system and grid-connected semiconductor green lighting system.
The characteristic of independent semiconductor green lighting is that the system can operate independently from the grid. Typical examples are the currently popular solar street lights, solar lawn lights and household solar lighting systems.
The grid-connected semiconductor green lighting system is the most economical and practical solar photovoltaic power generation system. The electric energy of the solar battery is sent to the grid through a DC/AC three-phase synchronous inverter. When the LED lighting needs electricity, it is taken from the grid. Since this system does not require a battery, it has high efficiency (the charging and discharging efficiency of the battery is 80%). %), and there is no worries about environmental pollution caused by batteries. At present, more than half of the solar cells produced in the world have been used in grid-connected power generation systems. In countries with advanced applications of solar cell power generation, such as Germany and Japan, grid-connected solar power generation has basically become popular. In this case, LED lighting is already a grid-connected semiconductor green lighting system, but people have not paid attention to this issue from the perspective of solar cell power generation.
Through the above analysis, it can be considered that the current understanding of semiconductor green lighting is the independent semiconductor green lighting that stays on LED lighting. Because of the emergence of solar cells, a new semiconductor energy source with great development potential, people have every reason to go from the system. Examine the semiconductor green lighting: it should be a semiconductor control circuit and semiconductor LED light source composed of semiconductor power generation, a pollution-free, the most ideal lighting system for human beings. It can also be called generalized semiconductor green lighting.
There should be countless “PN junctions” between the two “PN junctions”
Complicated, even very complicated control circuits are required to connect the solar cells to the LEDs. They are completely completed by semiconductor devices, that is, countless “PN junctions” are completed. In the independent semiconductor green lighting system, the battery needs to be charged and discharged; in order to meet the low voltage and constant current operating characteristics of the LED, high-efficiency voltage and current conversion and many controls such as automatic switching are required for the power supply. For grid-connected semiconductor green lighting systems, DC/AC three-phase synchronous inverters, solar cell maximum operating point tracking (MPPT) devices, and in order to meet the low voltage and constant current operating characteristics of LEDs, high-efficiency voltage and current are applied to the power supply Transformation and many controls such as automatic switches are also indispensable. Therefore, there should be countless “PN junctions” between the two “PN junctions” of solar cells and LEDs, which form a real semiconductor green lighting.
Semiconductor green lighting is not only the task of LED R&D and production departments. It should be the common task of silicon materials, solar cell manufacturing, solar cell module manufacturing, integrated circuit design and manufacturing, semiconductor power device manufacturing, and LED R&D and production departments. In particular, the design of application specific integrated circuits in the system is very important and urgent. The use of universal standard integrated circuits to manufacture semiconductor green lighting lamps cannot meet the needs of the market in terms of energy saving and price.
In addition to LEDs, ceramic metal halide lamps and three-primary fluorescent lamps (including electrodeless fluorescent lamps) are still one of the ideal light sources for solar lighting fixtures in the future. Ceramic metal halide lamps due to high luminous efficiency, high color rendering, dimmable performance and relatively low price should still have a place in solar lighting fixtures in the future; energy-saving fluorescent lamps (including electrodeless fluorescent lamps) can also be used due to their high cost performance .