(Guangdong Snowlight Optoelectronics Technology Co., Ltd., Foshan 528225)
Pick  To: Discuss the significance, characteristics and requirements of photovoltaic lighting, and introduce the characteristics, characteristics and parameters of the best-purpose light source low-power ceramic metal halide lamp for photovoltaic lighting.
Keywords: photovoltaic lighting, energy saving and emission reduction, ceramic metal halide lamp
I overview
The current huge amount of energy consumption has already posed a great threat to the world and to human beings. The drought and flood disasters, the severe cold and the violent storms that have been difficult for centuries, the homes of millions of people have been destroyed, displaced, the ruthless acid rain of all things, the years As usual, the gray sky and the raging yellow dust that has been hit by thousands of miles have caused human suffering. The changes in ecology and the extinction of species do not even know what kind of disasters to bring to future generations. The cost of non-renewable energy is the root cause of all these disasters. How to improve this state has become an urgent need today. Energy conservation and emission reduction and environmental protection are urgent issues.
About 14% of the huge electrical energy that people consume huge amounts of energy is used for lighting. This is a huge energy consumption, and the amount of CO 2 and SO 2 emitted is also very amazing. There are still a large number of the most energy-efficient incandescent lamps and tungsten halogen lamps in the currently used illumination sources. If such light sources are replaced by energy-saving light sources, the electricity consumption for lighting can be reduced by 2/3, so that the total electricity consumption in China can be reduced by 9%. , and the emissions of CO 2 and SO 2 will also decrease accordingly.
For hundreds of millions of years, the sun has been continuously transmitting energy to the Earth in the form of light radiation. It is estimated that the total radiated power of the sun that is projected endlessly to the Earth is about 170 trillion kilowatts. The total radiation is absorbed by the atmosphere and reaches the Earth's surface. There are still about 80 trillion kilowatts, and the power projected on our country is no less than 2 trillion kilowatts. Even if one ten thousandth of them is used, there are 200 million kilowatts. The solar energy available for the whole year is 8 hours of sunshine per day. Approximately 600 billion kWh, it can be seen that the use of solar energy has enormous potential value.
The photosynthesis of plants absorbs part of the energy radiated by the sun to the surface of the earth, and the rest is absorbed by the earth's surface land and ocean, converted into heat and caused various changes on the surface of the earth, such as the appearance of the four seasons, such as the formation of wind and lightning. This has created vitality for the earth, creating hundreds of millions of creatures including human civilization, but at the same time creating a lot of disasters for mankind. The hydraulic, wind and tidal forces that humans have been using for years, including sun exposure, are also direct and indirect uses of solar energy, and such use is too little. Coal, oil, etc. are the modern application of solar energy stored in the earth for hundreds of millions of years. This application is too much. According to the current level of technology that humans have mastered, people have been able to convert solar energy directly into electrical energy. The easiest way is to use a specially made substance such as a specially processed (doped) silicon wafer of semiconductor material when the sun shines on it. A certain surface on a silicon wafer will produce a photovoltaic effect, and a certain potential difference will be formed between the two sides. Such a silicon wafer becomes a so-called photocell that supplies power to humans.
The pn structure between the n-type and p-type semiconductors of the doped silicon wafer becomes a barrier layer, and after the n-type semiconductor absorbs photons under illumination, the electron transition at the donor (impurity) level becomes into the conduction band. Free electrons and gather the surface to make it negatively charged. At this time, a potential difference is generated between the n-type semiconductor and the p-type semiconductor which is not exposed to the other side, which is a so-called photovoltaic effect. When the external line is turned on, the photoelectron will flow from the n-type semiconductor to the p-type semiconductor through the load, into the acceptor level (positive hole), and then flow back into the n-type semiconductor through the barrier layer to return to the donor level, and again under the sunlight. Enter the conduction band to provide power to the load source. The sun is the largest source of radiation in people's environment, and the photovoltaic effect of using solar radiation naturally becomes an ideal source of energy. This waste is not emitted during the production of this energy, so this is a clean energy source.
At present, the photovoltaic power that people use solar energy can provide limited power. Although the total energy consumption of the whole lighting is huge, and the lighting is very scattered, the single lighting system is small and consumes a small amount of electricity. It can be independently powered by a small solar power generation system, and the current technical level can be fully realized. For example, in an open area, every home or even every lamp is an independent lighting system. For such a capacity system, a few small photovoltaic panels, a properly-capacity energy storage battery and a simple control circuit can ensure reliability. Night lighting.
The photovoltaic effect has been applied in the history of human technology for nearly a hundred years. The earliest selenium and cuprous oxide photovoltaic cells did not provide electricity to people, but used as a signal for detecting light and determining the intensity according to the level of the conversion voltage. Until about 40 years ago, silicon photovoltaic cells began to be used to power some small appliances such as calculators. The application of photovoltaic effect as energy source starts from artificial satellite. In addition to solar energy in distant space, it is impossible to easily obtain other energy sources. At this time, people have learned how to use the photovoltaic effect of solar energy to the artificial satellite for a long time without interruption. Providing the necessary electrical energy for operation, photovoltaic cells have grown rapidly since then. The solar photovoltaic cell of the artificial satellite is made of monocrystalline silicon wafer, and its optical-electrical conversion efficiency is relatively high and expensive. In order to provide sufficient power, single crystal silicon photovoltaic cells for satellites are very large and expensive. Satellites are cost-free, and the success of this application has driven the rapid development of solar photovoltaic cells.
With the development of technology, the method of manufacturing photovoltaic cells has been greatly improved, the process has been simplified, the cost has been greatly reduced, and large-scale industrial production has begun, but even now, its power generation cost is more than ten times more expensive than conventional thermal power generation.