Abstract: The solar energy is a clean, green renewable energy; semiconductor light-emitting diode (LED) is also a kind of environmental protection, energy saving and efficient, solid-state light sources. The article in the analysis of both technical characteristics on the basis of focus on a combination of both - the semiconductor solar lighting system and the efficiency of the feasibility of a demonstration, and the future development of the analysis and forecasts.
1, the preamble
The 20th century, petroleum, coal, natural gas and other energy resources facing the danger of depletion, at the same time, the increasing pressure of environmental protection, environmental protection, energy saving has become the trend of development of all walks of life. Solar energy on the planet as a truly inexhaustible supply of clean energy, will be the 21st century the best new green energy, its use is an effective way to use photovoltaic power generation technology will transform solar energy to electricity. LED (Light Emitting Diode) is a kind of power can be converted into visible light of semiconductor devices, by virtue of its non-polluting energy-saving features have been used in many industries in the area of the lighting, so as integrated solar photovoltaic and advantages of LED solid-state lighting The solar LED lighting systems, a new generation of energy and is the perfect combination of a new generation of light source.
2, solar photovoltaic technology features
Solar photovoltaic solar cells that rely on components (Solar Cells), the use of electronic semiconductor material characteristics, when the sunlight in the semiconductor PN junction, due to P-N node barrier area has strong built-in Electrostatic field, creating the barrier in the area of non-equilibrium electron and hole, or produce the barrier but outside the barrier into the spread of the area of electronic and non-equilibrium hole, in the role of built-in electrostatic field, to the The opposite direction of movement, left the barrier, resulting in higher potential areas P, N area to reduce potential to produce outstanding circuit voltage and current, the conversion of light energy into electrical energy.
Solar photovoltaic systems in general can be divided into two categories is the network and power generation systems, and public power grid connected through a standard interface, like a small power plants in other is self-generating system, In their own closed-circuit system formed, and no external power grids have a relationship. Net and photovoltaic power generation systems through the array will receive the solar radiation energy to the high-frequency DC converted into a high-voltage direct current, the inverter to the power grid after the inverter output voltage and frequency and power grids, with the sine of AC current. And the stand-alone photovoltaic power generation system will first receive arrays to the direct solar radiation energy into electric energy supply load, and excess energy after the charge controller in the form of chemical energy stored in batteries. The lack of sunshine, stored in a battery of energy through full-bridge inverter SPWM after a wave and then after filtering and frequency transformers boost exchanges after a 220 V, 50Hz sine the use of load voltage supply exchanges.
3, LED semiconductor lighting of the technical characteristics
LED is a node in the P-N being imposed on the current issue of when to UV, visible light, infrared light of the solid semiconductor devices. Its luminous mechanism lies in P-N junction, when the plus forward voltage, P-N end balance was broken, P District hole into the P-N and in the end part of the original negative ions, N e into the P - N junction in the part of the original and positive ions, so that the P-N narrow end, the external electric field to P-N lower electric guitar, electronic energy caused the decrease, reducing the potential energy is converted into electromagnetic energy, in the form of a photon Release. Electronic reduce the energy more, the release of the higher photon energy. LED light to release the energy and the electricity and electronic lit voltage on the diode, or E = qV (J) (q =- 1.6 × 10-19C). And the release of the peak wavelength of light, and LED chips used in semiconductor-related materials, λ ≈ 1240 / Eg (nm) (width of the semiconductor material cut Eg <ev>), calculated know if produced by the visible light, the chip used in Eg the semiconductor material should be between 1.60 ~ 3.26 ev, which is the development and selection of luminous different wavelengths of light chips based on the material.
LED semiconductor lighting source with a wide range of advantages, in addition to long life, LED high efficiency, small size, light weight, environmental safety and reliability advantages, there is a significant advantage due to start LED voltage and voltage line, so do not Requires the use of ballast. This and related cost savings in energy consumption, while also greatly shortened the response time-off.
4, solar energy and the combination use of LED lighting
4.1, the efficiency of systems analysis
Solar photovoltaic technology with LED lighting perfect combination of the two is the key to the same DC, low voltage and can match each other. The combination of solar energy would need converter (PV) cells into the AC DC, greatly improving the efficiency of the entire lighting system. At the same time, help and network technology or rechargeable-battery, which has obvious advantages. To be able to fully match the two, we have created a model for analysis. Were selected halogen, compact fluorescent lamps (CFL), linear fluorescent lamps (LFL) and four LED light source, power supply for PV lighting systems in the comparison of different systems to assess the overall efficiency in order to determine the impact on the efficiency of the system And various factors in the field of application of the best system configuration. Model shown below.
Through the establishment of the under-the efficiency of the whole system to calculate:
Ef=Kpv×Kbat×KAC×Kcond×Kreg×Kinv×Ksrc×Klum Ef = Kpv × Kbat × KAC × Kcond × Kreg × Kinv × Ksrc × Klum
One, Ef-building PV lighting systems in the overall power supply efficiency;
Kpv-PV module efficiency, as 20 percent;
Kbat-cell efficiency, as 85% (If the system does not include the battery is 100%);
KAC-AC load center efficiency, as 90% (If the system does not include AC load center is 100%);
） Kcond-accumulator efficiency, as 87% (If the system does not include accumulator of 100%)
Kreg-DC current regulator efficiency (if not the LED light source for 100 percent);
Kinv-DC-AC inverter efficiency (if the LED light source as compared to 100%);
Ksrc-efficient light source, lm / W;
Klum-efficiency lamps, lamp with a total flux of all the lamps light the issue of the ratio of the total flux.
PV powered lighting systems in various parts of the efficiency as shown in table 1.
According to the formula and set of values, can be calculated in directional lighting applications in the different light sources PV power supply efficiency of the lighting system, the results as shown in table 2.
From Table 2, we can see that the use of the white LED system efficiency halogen higher than doubled, with the CFL basically the same. But compared with LFL there are still some gaps, The reason is because a single white LED luminous efficiency is relatively low. But with the in-depth technical studies, LED luminescence efficiency is constantly growing quickly, I believe that in the near future ultra-high brightness LED fully able to replace the LFL.
4.2 Market Analysis
Solar LED lighting products is the next generation of green lighting products, its main components, including solar photovoltaic cells (PV technology) and semiconductor lighting source (LED).
Since 1997, photovoltaic technology of the future development prospects have been more and more of the national government and financial sectors (such as the World Bank) agree. Many developed countries and regions have developed photovoltaic development plans. U.S. plans to install in 2010 a total 4.6 GW (U.S. Department of Energy planning, with "millions of the roof"); European Union plans to install a total 6.7 GW ( "Renewable Energy White Paper"), of which 3.7 GW installed in Europe, 3GW exports, and so on. Is expected the next 10 years, the production of photovoltaic components will be 20 percent to 30 percent the speed of development, to the 2010 global PV installation rate will reach 3.2 kMW, PV turnover will increase to 18.5 billion U.S. dollars, the market Will also be in rural and remote areas of energy gradually add the whole society of alternative sources of energy transition. To the middle of the 21st century, solar photovoltaic power generation will reach the world's total generating capacity of 15 percent to 20 percent, becoming one of mankind's energy base.
Similarly, as a solid-state LED light source of the rise, the real is conducive to promoting the "green light" projects. "Green light" is the early 1990s on the international energy conservation, environmental protection, the image of the lighting system is. In the consumption of electricity, lighting a large proportion of electricity, green energy-saving lighting application of more and more attention, LED is in such a situation develop. With the addition of new materials and the development of the semiconductor industry, LED especially luminous efficiency white LED continuous improvement, prices declined. Use of LED characteristics associated with the development of new technologies to apply to different occasions and purposes of the lighting systems, lighting can be said of its market potential would be immeasurable. LED to 2004 the total global sales have reached 380 billion U.S. dollars, compared with 2003, the growth rate of 36 percent. According to the forecast, to 2008, LED of the total global sales will reach or even over 600 billion U.S. dollars, so that it truly replace incandescent, fluorescent lamps and other traditional energy sources, a new generation of green light.
Solar lighting products in the current Although some manufacturers have developed products, and put into practical application, but because of small LED power, its use of the great constraints. With the high-brightness LED light the continuous improvement of efficiency, coupled with energy-saving people's increasing awareness of environmental protection, solar lighting products will play its zero-energy consumption, pollution-free characteristics, their applications will continue to widen.
5 summary
Green energy and sustainable development issues facing humanity this century is a major issue. The development of new energy, the existing fully rational use of energy has been of great importance to Governments. At present, the utilization of solar energy technology and semiconductor lighting industry has from the beginning of pioneering technology into the commercialization stage, the products include lighting street lamps, traffic instructions, landscape lighting, garden decoration, and so on, through the technical features of the system and feasibility analysis, We believe that the collection of a new generation of energy and a new generation of semiconductor light source advantages of solar lighting system will be at unprecedented speed development, and lead us into a new era of green energy.