Solar power

Solar energy is from outside the earth objects (mainly solar energy), is in the sun hydrogen atom Nuclear in ultra high temperature fusion A huge release of energy, the energy needed for the human most directly or indirectly from the sun. For we live in coal oil, natural gas and other fossil fuels are because of various plants to convert solar energy into chemical energy stored in plants down through photosynthesis by plants and animals buried in the underground after a long Geologic Age Form. In addition, hydropower, wind energy, wave energy, ocean current energy is also caused by the conversion of solar energy.
Solar power

Solar power background

Solar power Energy situation

With the development of economy and society, people put forward higher requirements on energy, find new sources of energy has become an urgent issue facing humanity. There are 3 main sources of existing power, i.e. Thermal power , hydropower , nuclear power and Wind power generation .
The burning of coal, oil and other fossil fuels to power. On the one hand, the fossil fuel reserves are limited, more and more small, are facing the danger of exhaustion; on the other hand, the combustion will emit carbon dioxide and sulfur oxide, thus causes Greenhouse effect And acid rain, deterioration The earth's environment .
Water to drown a lot of land, may lead to ecological environment Destruction and collapse of large reservoirs once the collapse will be unbearable to contemplate the consequences. In addition, one of the country's water resources are limited, but also by the influence of the season.
Nuclear power under normal circumstances is clean, but in case of Nuclear leakage Also, the consequences are terrible. The former Soviet Union, Chernobyl nuclear power plant accident Has made 9 million people have different degrees of damage; 13:46 on March 11, 2011, 9 earthquake in Fukushima, triggered the Fukushima nuclear power plant accident shocked the international, caused by the nuclear power plant near 30 km become uninhabited 5 kilometers; marine resources will be affected in different degrees or marine biological variability.
Wind power as a clean and renewable energy, has broad prospects for development. The wind energy reserves, the extensive development of wind power generation is an effective way to solve the shortage of energy supply Chinese; application of wind power is a clean energy, is an effective way to reduce greenhouse gas emissions.

Solar power The ideal energy

New energy to meet two conditions: one is not depletion of rich; the two is safe, clean, not a threat to humans and the destruction of the environment. There are two main types of new energy found, a solar energy is two fuel cell .
In twenty-first Century, solar energy will become one of the main energy in the world, is the most primitive energy on earth, almost all other energy comes from solar energy directly or indirectly. Solar energy is The interior of the sun Or spots on the surface of continuous nuclear fusion The energy generated in the reaction process. Solar energy has abundant resources and long life, widely distributed, safe, clean, reliable technical advantages. Because the solar energy can be converted into a variety of other forms of energy, so the application range is very wide, solar greenhouse, and the dry goods solar cooker, solar water heater in heat utilization. After years of development, solar power has also been considerable development.
Obtained from solar power for photoelectric conversion through the solar battery to achieve. It with other power generation principle of the past entirely different. To make solar power truly practical level, one is to improve the efficiency of solar photoelectric conversion and reduce the cost, the two is to achieve the same solar power power grid Networking.

Solar power classification

Solar power Solar power

Solar power is a thermal process without the need for directly converting solar energy into electricity. It consists of photovoltaic power generation, power generation, power generation and light induced photochemical light biomass power generation. Photovoltaic power generation using solar light radiation level semiconductor electronic devices to effectively absorb the sun, and transformed into direct electricity generation, is the mainstream of the solar photovoltaic power generation. Electrochemical photovoltaic cell, in the photochemical generation photoelectrolytic cell and photocatalytic battery, currently applied is photovoltaic cell.
Photovoltaic power generation system consists of solar battery, battery, controller and inverter, which is the key part of the solar photovoltaic system, solar panels of the quality and cost of the entire system will directly determine the quality and cost. The solar cell is divided into crystalline silicon solar cell and thin film batteries two, including batteries, two monocrystalline silicon polycrystalline silicon solar cell, which includes non crystal silicon solar battery and CIGS solar cells and CdTe solar cell.
The photoelectric conversion efficiency of monocrystalline silicon solar cell is about 15%, up to 23%, the highest photoelectric conversion efficiency in solar cells, but its high manufacturing cost. Monocrystalline silicon solar battery life up to 15 years, up to 25 years. The photoelectric conversion efficiency of polycrystalline silicon solar cell is 14% to 16%, the production cost is lower than single crystal silicon solar cell, so get a lot of development, but the polysilicon solar battery life is shorter than that of monocrystalline silicon solar cells.
Thin film solar cell solar cell as matrix material for silicon, gallium arsenide, cadmium sulfide thin film. The base material of thin film solar cell can use lightweight, low price (such as glass, plastic, ceramics etc.) to manufacture, forming a thin film thickness can produce voltage less than 1 microns, convenient transportation and installation. However, depositing films on heterogeneous substrate will have some defects, so the existing CdTe and CIGS solar cell conversion efficiency of large-scale production of only 12% to 14%, and the theoretical limit of up to 29%. If you can reduce the defects of CdTe in the production process, will increase the battery life, and improve the conversion efficiency. This requires the causes of defects, and the way to reduce the defects and quality control. The solar cell interface is also the key that requires a lot of investment in research and development.

Solar power Solar thermal power generation

Through water or other fluids and the device will convert solar radiation into electricity, known as solar thermal power generation. To convert solar energy into heat, then heat into electricity, it has two ways: one is the conversion of solar energy directly into electricity, such as semiconductor or metal materials for thermoelectric power generation and thermoelectric power generation, hot electron ion vacuum device, alkali metal thermoelectric conversion, and MHD power generation; another way is through the solar heat engine (such as turbine) driving generator, power generation and conventional thermal similar, but is not the heat from fuel, but from solar energy. There are many types of solar thermal power generation, mainly has the following five types: Tower, trough system, disc system, solar pond and solar updraft tower power generation. The first three are concentrating solar thermal power generation system, after two non condensing. In some developed countries, solar thermal power generation technology as a national focus on R & D, manufacturing of dozens of various types of solar thermal power generation demonstration power plant, power generation has reached the level of practical application.
Currently available in the world the most promising solar thermal power generation system can be divided into: parabolic trough focusing system, the central receiver solar tower or focusing system and disc parabolic focusing system. Three forms of technically and economically feasible is: 30 ~ 80MW focus parabolic trough solar thermal power generation technology (referred to as parabolic trough); 30 ~ 200MW central receiving point focusing type solar thermal power generation technology (referred to as the central receiving type); 7.5 ~ 25kW point focus parabolic disc solar thermal power generation technology (referred to as parabolic dish type).
Heat transfer fluid focusing type solar thermal power generation system is mainly water, water vapor and heat transfer of molten salt, the refrigerant can be heated to 450 degrees Celsius and then used for power generation in the receiver. In addition, the heat storage system of the power mode can be temporarily stored heat for several hours to spare time for the peak.
Parabolic trough focusing system is launching sunlight to the receiver mirror tube using parabolic trough, and heating the heat transfer tubes, steam is produced in hot air exchanger, conventional steam turbine drive. Tower solar thermal power generation system is the use of a group of independent tracking solar heliostat, focus sunlight to the receiver a fixed on the top of the tower to produce high temperature.
In addition to the above several traditional solar thermal power generation, new research field of solar chimney power generation, solar pond has also made progress.

Solar power Power generation device

Solar power is the use of solar battery components will be directly converted into electrical energy device. The solar cell module (Solar cells) is a solid device to realize P-V conversion using the electronic properties of semiconductor materials, in the absence of power network area is vast, the device can be conveniently implemented as user life lighting and power supply, some developed countries can also achieve complementarity and regional power grid. At present, from the civilian perspective, in the study of foreign mature technology and its industrialization is "photovoltaic building (lighting) integration technology, and focuses on domestic production for areas without electricity home lighting in small-scale solar power generation system.
The solar power generation system mainly includes: solar battery components (array), controller, battery and inverter, which is composed of a lighting load user. The solar cell module and battery for power supply system, controller and inverter control and protection system, load terminal system.
The solar battery and the Battery A power supply unit of the system, so the battery performance directly affects the working characteristics of the system.

Solar power Battery unit

Due to technical and material reasons, generating capacity of single battery is very limited, the practical solar cell battery system single cells by series and parallel composition, called cell components (array). A single battery is a silicon diode, according to the electronic properties of semiconductor materials, when the sun light is composed of a P type and N type of two different types of homogeneous conductive semiconductor material P-N junction, under certain conditions, the solar radiation absorbed by the semiconductor material, resulting in the conduction and valence bands Non equilibrium carriers The electron and hole. The same as P-N node barrier region there is strong built-in electrostatic field, thus forming the current density J under illumination, the short-circuit current of Isc, the open circuit voltage Uoc. Two if the built-in electric field side electrodes and connected to the load, by P-N junction, connecting circuit and load loop formed by the theory, there is "photocurrent" flow, solar cell module is realized on the P power output load.
Theoretical study shows that the peak power of Pk solar cell components, by the local average solar radiation intensity and the end of the electricity load (demand) decision.

Solar power The storage unit

DC power generated by the solar cell to enter the storage battery, Battery The characteristics affect the work efficiency and the characteristics of the system. Battery technology is very mature, but its capacity to demand by the end, the sunshine time (generation time) effect. So the battery capacity and watt ampere hour capacity by a predetermined continuous sunshine time decision.

Solar power Controller

The main function of the controller is to make solar power system is always in the vicinity of the maximum power point of power, to achieve the highest efficiency. The charge control is usually used Pulse width modulation Technology is the PWM control mode, the whole system is running in the area near the maximum power point Pm. Discharge control mainly refers to when the battery power shortage, fault system, such as open circuit or reverse connection switch. At present Hitachi Developed can not only track the control point of Pm, and can track the sun moving parameters of the "sunflower" type controller, efficiency of the fixed battery component is increased by about 50%.

Solar power inverter

inverter According to the incentive way, can be divided into self-excited oscillation and lfyback oscillation inverter inverter. The main function is the battery DC reverse into alternating current. The full bridge circuit, generally use the SPWM processor through modulation, filtering, boost, and lighting load frequency f, sinusoidal alternating current, rated voltage of UN system for terminal users.

Solar power Reverse charging diode

Reverse charging diode solar photovoltaic power generation system is also called blocking diode, the solar cell module in its role is to avoid the solar array in the rainy night and no power or short circuit fault occurs, the battery discharge through the solar cell array. Reverse charging diode in series with the square circuit in the solar cell, one-way conduction effect. Therefore, it must ensure that the maximum current in the circuit, but also to withstand the maximum reverse voltage impact. You can choose the suitable rectifier diode as reverse charging diode. In a word without any diode, because the controller is capable of preventing recoil. The board series, need to install the bypass diode, if you have to put in a parallel anti recoil diode, prevent direct charging board. Anti reverse charge protection diode only, will not affect the effect of power generation.

Solar power efficiency

In the solar power system, the total system efficiency by ese battery module PV conversion rate controller, efficiency, battery efficiency, inverter efficiency and load efficiency etc.. But compared to the solar cell technology, than the controller, inverter and other lighting load unit technology and production level was much more mature, but the system conversion rate is only about 17%. Therefore, to improve the conversion rate of the battery components, reduce the unit power cost is the key and difficult point of the solar power industry. Since the advent of crystal silicon solar cell, as the protagonist of materials to maintain a dominant position. Study on the conversion rate of the silicon cells, mainly around the increase energy absorbing surface, such as double the battery, reducing reflection; using composite gettering technique to reduce semiconductor materials; ultra-thin battery; improvement of the theory, the establishment of a new model; concentrating cell etc..

Solar power The advantages and disadvantages

Solar photovoltaic power generation has many unique advantages:
1, solar energy is inexhaustible and clean energy, and solar photovoltaic power generation is safe and reliable, without being affected by the energy crisis and fuel market instability;
2, the sun shines on the earth, solar energy is available, solar photovoltaic power generation in remote areas without electricity especially, and will reduce the long distance power grid construction and transmission line of power loss;
3, the solar energy does not require the production of fuel, the operation cost is greatly reduced;
4, in addition to tracking type solar photovoltaic power generation, no moving parts, so it is not easy to damage, relatively easy installation, simple maintenance;
5, solar photovoltaic power generation will not produce any waste, and does not produce noise, greenhouse and toxic gas, is the ideal clean energy. The installation of 1KW photovoltaic power generation system, the annual emission of CO Two 600 ~ 2300kg, NOx16kg, SOx9kg and other 0.6kg particles;
6, can effectively use the roofs of buildings and walls, do not need to take up a lot of land, and the solar panel can directly absorb solar energy, thereby reducing the roof and wall temperature, reduce indoor air conditioning load;
7, solar photovoltaic power generation system and power generation module construction cycle short, long service life, generating a more flexible way, energy recovery cycle power system short;
8, from resource distribution Geographical restrictions; nearest department in electricity generation.
Everything has its two sides, although the solar photovoltaic power generation has many advantages above, but also has its disadvantages:
1, the geographical distribution, seasonal variation, diurnal cycles will seriously affect the power generation, when no sun cannot power or power is very small, it will affect the normal use of electrical equipment;
2, the energy density is low, when large-scale use, the occupied area will be relatively large, the solar radiation intensity;
3, the cost of photovoltaic system is still relatively high, the system cost 40000 to 60000 yuan /kW, high initial investment seriously restrict its wide application;
4 years, when the generation number is low, an average of 1300 h;
5, the accurate prediction of system power generation is difficult.

Solar power The status quo and Application

Solar power Present situation

The use of solar energy is mainly divided into several aspects: small family Solar power station And the large power grid, building integrated photovoltaic glass curtain wall, Solar street lamp , Scenery complementary lamps And scenery complementary power supply system etc., Wind solar hybrid system .
The use of solar energy is not very popular, the use of solar power also has high cost, low conversion efficiency, but Solar cell Has been used in providing energy for artificial satellites. Solar energy is The interior of the sun Or spots on the surface of continuous nuclear fusion The energy generated in the reaction process. The average earth orbit solar radiation The intensity of 1369w/ square meters. The earth's equator is 40000km, which can be calculated that the earth energy is 173000TW. The standard peak intensity at sea level is 1kw/m2, the average radiation intensity of the earth's surface at a point 24h is 0.20kw/ square meters, the equivalent of 102000TW energy, human beings rely on these energy to survive, including all other forms of renewable energy sources (geothermal resources except), though Solar energy resources Now more than ten thousand times the amount equivalent to the use of human energy, but solar energy energy density Low, but it varies from place to place, from time to time change, this is the main problem facing the development and utilization of solar energy. These features will make solar energy is limited in the integrated energy system of the role. Although the solar radiation to the earth's atmosphere is only the total energy Radiation energy Of the 2 billion 200 million, but has been as high as 173000TW, that is to say a second exposure to the sun's energy on earth is equivalent to 5 million tons of coal. Earth wind, Water , Ocean thermal energy , Wave energy And biomass as well as some Tidal energy It is from the sun; even on earth fossil fuel (such as coal, oil and natural gas) is fundamentally since ancient times the storage of solar energy down, so by including a broad range of solar energy is very large, the narrow sense is limited to solar Solar radiation The direct conversion of solar thermal, photovoltaic and photochemical.
Solar power is affected by the seasons, day and night, rain or shine, but can be scattered, so it is suitable for the families of power, and connected to the power supply network, making the family rich in the power may be sold to power companies, but from the lack of electric power companies to buy. Implementation of this technology is not difficult, the key is to have the appropriate legal protection. Now the United States Japan and other developed countries have enacted appropriate legislation to ensure domestic solar power generation benefits to encourage families to carry out solar power generation.
Japan in April 1992 to achieve The solar power generation system With the power grid network, some families began to install solar power equipment. MITI from 1994 began to implement personal residence as the object, the cost of subsidies for the purchase of 2/3 solar power generation equipment system. There are 1000 households in 2000, the first year there are 70 thousand households with solar power generation equipment. According to the Japanese authorities estimated 21 million Japanese households residential if there are 80% installed solar power generation equipment, can meet the needs of the national total power of 14%, if the factory and office building and other units of the solar power generation houses, while solar power will account for the power of 30% - 40%. The most important factors hinder the popularization of the solar power is expensive. In order to meet the needs of the general family power of 3 kilowatts of power generation system, 6 million to 7 million yen, not including installation of wages. Experts believe that, at least to 1 million to 2 million yen, the solar power can really spread. The key is to reduce the cost of solar cells to improve the conversion efficiency and reduce the cost.
U.S.A TI company And SCE company announced that they developed a new solar cell, each unit is less than 1 mm in diameter of beads, they packed regularly distributed in the soft aluminum foil, like many canluan clingy on paper. In about 50 square centimeters of area and distribution of 1700 such units. The characteristics of this new battery, although the conversion efficiency is only 8% - 10%, but the price is cheaper. But the aluminum foil backing cloth like soft fruit, can freely like folding and durable, hanging on Xiangyang Power will be very convenient. Allegedly, the use of the new solar cell, per watt of electricity generating capacity of the equipment as long as 1.5 to 2 dollars per kilowatt, and cost can be reduced to around 14 cents, with the ordinary can Power plant Have the power to compete. Each family will be hanging in the battery Xiangyang roof, walls, each year can get one thousand or two thousand kwh of power.

Solar power application area

1, users of solar power: small power ranging from 10-100W, used in remote areas without electricity, such as plateau Island, pastoral areas, border posts and other military and civilian living electricity, such as lighting televisiontape recorders; 3-5KW family roof grid connected power system; photovoltaic pump: to solve the areas without electricity deep wells for drinking and irrigation.
2, transportation: such as beacon lights, traffic lights, traffic warning / railway / sign lamp, street lamp, high-altitude obstacle lamp, highway / railway wireless telephone booth unattended power station etc..
3, the field of communication / communication: solar unattendedmicrowave relay station cable maintenance station, radio / communications / paging power system; rural telephonecarrier photovoltaic system, portable communication machine, power supply GPS soldiers.
4, petroleum, marine meteorological fields: oil pipeline and the reservoir gate cathodic protection solar power system, the life of the oil drilling platform and emergency power supply, testing equipment, marine meteorological / hydrological observation equipment etc..
5, family lamp power: such as courtyard lamp, street lamp, portable lamp, Camping lamp Mountaineering, fishing lights lights, black lights tapping lamps, energy saving lamps.
6, 10KW-50MW photovoltaic power plant: independent photovoltaic power plants, scenery complementary power station (diesel), a variety of large-scale parking lot charging station etc..
7, solar building: combining solar power and building materials, the large building future power self-sufficiency, is a major development direction in future.
8, other areas: Automobile Accessories: solar and electric vehicles, battery charging equipment, automobile air conditioner, fan, cold boxes of renewable power generation system; solar hydrogen fuel cell power supply; desalination equipment; satellites, spacecraft, space solar power station. ,

Solar power Design and research

To successfully integrate solar modules and building components, such as Solar Roofing (roof), walls and doors and windows, to achieve the "building photovoltaic lighting integration (BIPV)". In June 1997, the United States announced by the president named the "million solar roofs plan", the implementation of the solar power system for 1 million homes in 2010. Japan's "new sunshine plan" in 2000 before the building components of PV installed cost reduced to 170 ~ 210 yen /W, the annual output of 10MW solar battery, the battery cost reduced to 25 ~ 30 yen /W. In May 14, 1999, Germany only two months a year built the world's first zero emission of solar battery components factory, complete with renewable energy to provide power, CO2 emissions in the production. The factory south wall to PV array glass curtain wall height of about 10m, including the roof PV components, solar cell components of the factory building with 575m2, only this can provide more than 1/3 of the electricity for the building, with its walls and roof PV components shape, color and architectural style and building, to coordinate the perfect integration with the surrounding natural environment. The building has about 45kW capacity provided by the natural state of rapeseed oil as fuel, the basic balance required for CO2 design produced by combustion of rapeseed oil and the growth of rape CO2, is a real sense of zero emissions plant. BIPV also focus on the study of Art Deco architecture, in Czech By the German WIP company and the cooperation of Czech, built the world's first color PV curtain wall. India West Bengal As a non electric Island 117 villagers installed 12.5kW BIPV. The Changzhou Tianhe aluminum curtain wall Manufacturing Co., Ltd. successfully developed a "solar house", the power generation, energy saving and environmental protection, the value of melt in a room, successfully combine the technology of photoelectric technology and architecture, called solar building system (SPBS), SPBS has been demonstrated by experts in September 20, 2000. Shanghai Pudong built the first solar lighting -- the integration of public toilets, all the electricity from the roof solar cell. This will effectively promote the solar building energy industry and the market process.
Optimization design of green lighting system, obtained the output of high light efficiency with low energy consumption, and prolong the service life of the lamp. Therefore, DC-AC inverter design, should be reasonable and the lamp filament preheating time excitation voltage and current waveform. In the solar lighting research and development incentives in four ways: the typical circuit of push-pull self oscillating circuit, series starter preheating by filament. The main parameters of the light source of the system are: input voltage DC=12V, output >495Lm/ light effect, the lamp rated efficiency of 9W, the effective life of 3200h, continuous open >1000 times. The self-excited oscillation (simple push-pull type) circuit, the main parameters of the light source system is: input voltage DC=12V, output power 9W lamp, 315Lm/ light effect, continuous start >1500 times. The self-excited oscillation circuit of single filament preheating start relay in series. The self-excited oscillation tube (simple type) green energy efficient light source circuit etc..

Solar power Solar cell

Solar power principle

The solar cell is a response to light and can be Light Conversion into electrical devices. Can produce Photovoltaic effect Many kinds of materials, such as: Monocrystalline silicon , polysilicon , Amorphous silicon Gallium arsenide copper indium selenium. Their power is basically the same principle, present in crystalline silicon for example to describe the process of light generation. P type crystal silicon available afterphosphorus doped N type silicon N junction formation, P.
 Photo photo Photo photo
When the light irradiation surface of solar cells, silicon material was part of photon absorption of photons; energy transfer To the silicon atom, make the transition of electrons, a free electron in the P - N junction on both sides gathered to form a potentialdifference when the external circuit is switched on, the voltage effect, there will be a current flowing through the external circuit to produce the output power.
The essence of this process: the photon energy into electric energy In the process of.

Solar power production

The production process can be divided into five steps: a purification process B, the process of pulling rod C slicing process D, process e, process of battery package. Based on the single crystal silicon as an example, the production process can be divided into:
A process: silicon wafer Washing wool
The purpose of this surface treatment, remove surface oil and metal impurities; removal of silicon surface damage layer cutting. In the production of textured silicon surface to form an anti reflective texture, reduce surface reflectivity. The use of Si in dilute anisotropic etching in NaOH solution, the formation of Pyramid structure of 3-6 microns on the surface of the silicon wafer, this light will be on the surface of the silicon wafer after repeated reflection and refraction, increase the absorption of light.
Step two: diffusion
Single / double liquid source of phosphorus diffusion in silicon wafer, making N emitter region, to form the basic structure of photoelectric conversion: PN junction.
POCl3 liquid molecule in N2 carrier gas carried into the furnace tube at high temperature after a series of chemical reactions and the phosphorus atom is replaced and diffused into the silicon surface formed activated N doped with P type substrate, forming a PN junction. The chemical reaction type mainly as follows: POCl3 + O2, P2O5 + Cl2 P2O5 + Si, SiO2 + P.
Step three: plasma edge moment
Short circuit ring removal diffusion silicon wafer periphery.
Step four: remove phosphorus silicon glass
The removal of phosphorus silicon glass forming silicon wafer surface oxidation layer and diffusion (the phosphorus silicon glass refers to the SiO2 layer doped with P2O5)
.
Step five: PECVD
Aimed at reducing reflection + passivation, plasma enhanced PECVD Chemical vapor deposition Plasma Enhanced Chemical Vapor Deposition equipment, production; reduce SiN film reflection surface of a silicon wafer (~ 80nm); contain substantial amounts of hydrogen ions in the SiN films, hydrogen ion implantation into silicon, reach the surface and bulk passivation to reduce the recombination of carriers, improve the short-circuit current and open circuit voltage of battery. The reaction of silane and ammonia SiN deposition of antireflection coating formed on the surface of silicon wafer. utilize High frequency power supply The glow discharge plasma Chemical vapor deposition Influence of technology. As the plasma gas molecules, promote the decomposition and synthesis, excitation and ionization, promote the formation of reactive groups, thereby reducing the deposition temperature. PECVD at 200 to 500 DEG C within the scope of the film, far less than other CVD at 700 to 950 DEG C within the scope of the film. The reaction process has substantial amounts of hydrogen ions into silicon, the silicon dangling bond defects, saturated lose activity, achieve the purpose of surface and bulk passivation.
Step six: screen printing
Screen printing method, complete the back field, the back electrode, making positive gate wire electrode, has led to produce photocurrent. For silver or aluminum paste of silicon surface printing a pattern, by sintering to form ohmic contact, make the output current; Ag positive electrode materials of metal, usually printed grating linear, have high transmittance of light in making good contact at the same time; the back is usually printed over the entire back of slurry with Al gold. One is to overcome the resistance caused by the battery series, two is on the back of the composite decreased.
Step seven: drying and sintering
Drying metal slurry, and the volatile additive (the former 3 District); on the back of the formation Aluminum silicon alloy Silver and Aluminum Alloy, to making good contact (the middle 3); the process of Al Si alloy is actually a P doping of silicon process, heating to Al Si eutectic melting point (577 C) above. After alloying, with the decrease of temperature, the liquid phase silicon will re solidification, forming the crystalline layer containing a small amount of aluminum, it compensates for the donor impurity in the N layer, P layer obtained by aluminum acceptor, can eliminate the back to. In front of the formation Silver silicon alloy And in good contact and shading rate; Ag slurry in glass material in high temperature (~700 degrees) under burnthrough SiN film, Ag makes the metal contact surface of the silicon wafer, the silver silicon melting point (760 degrees) above alloying.

Solar power prospect

The application of solar cells has been from the military and aerospace fields into the industry, business and agriculture, communication, household appliances, utilities and other departments, especially in remote areas, scattered mountains, desert island, and the countryside, in order to save the cost of transmission line is very expensive. But at present, its cost is also high, a 1kW investment of tens of thousands of dollars of electric needs, thus still subject to restrictions on the use of large-scale economy.
But in the long run, with the improvement of solar cell manufacturing technology and the invention of new light - electricity conversion device, all countries for the protection of the environment and a huge demand for renewable clean energy, solar cells will still be using solar radiation method is feasible, for future human large-scale use of solar energy to open up broader prospects.

Solar power Distributed solar power generation

Solar power application

Distributed photovoltaic power generation The system, called distributed generation and distributed energy supply, refers to the user site or close to the photovoltaic power supply system of electric field configuration is small, to meet the specific needs of users, support the existing economic operation of distribution network, or at the same time to satisfy these two requirements.
The basic equipment of distributed photovoltaic power system including photovoltaic modules, photovoltaic array bracket, DC bus box, DC power distribution cabinet, inverter, AC distribution cabinets and other equipment, and power plant monitoring device and environmental monitoring device. The operation mode is in the solar radiation conditions, solar panels convert solar energy photovoltaic power generation system output power, through the DC bus box concentrated into the DC power distribution cabinet, inverter grid connected inverter by alternating current supply of building its own load, excess or insufficient power to regulate through grid connection.
The scope of application system: in rural and pastoral areas, and in the development of medium and small city or near the downtown building small distributed power plant, to solve the power demand of local.

Solar power Program features

The system is independent of each other, to control, to avoid the occurrence of large-scale power outages, high safety;
To make up for lack of stability of the power grid, power supply to continue at the time of the accident, become an important supplement to the centralized power supply indispensable;
Quality and performance of the regional electric power real-time monitoring, is suitable for mountainous rural and pastoral areas, power supply, residents in the development of medium and small city or commercial area, greatly reducing the environmental pressure;
Transmission loss is low, even no, no need to build the power station, reduce or avoid the additional costs of transmission and distribution construction and installation cost is low;
Peak performance is good, the operation is simple; because the system in running, start and stop fast, easy to realize automatic.

Solar power Maintenance and maintenance

1, Solar photovoltaic power generation system In photovoltaic Square: check and tighten the bolt and wire, test output, adjust the angle.
2, tracker: lubricating bearings, check the bolts and shock.
3, spare fuel system: determine the connection, and have intact, readily available.
4, charging controller: check the voltage settings, check the voltmeter indicating normal. If the battery temperature is below 55 DEG F, should be allowed to charge high voltage (12 volt system for at least 14.8 volts). If you charge controller with temperature compensation function, automatic adjustments. If there is an external temperature sensor, that has been posted on the battery. If there is no automatic adjustment function, the need for manual voltage is high, and back in the spring Shidiao (to 14.3 volts). If the charging controller is not adjustable, try to keep the battery in a warm environment.
5, battery (lead-acid battery): check voltage, failure to exclude, and determine the need for balanced charging. If you need to charge balance maintenance (usually 8 hours of moderate overcharge again in the battery is full). The liquid or dust accumulator above wash (with dry soda acid precipitate). Terminal cleaning or replacing corrosion. In the terminal coating vaseline to prevent further corrosion. Check the battery liquid, if necessary, add distilled water or deionized water. Check ventilation (ventilation pipe if the insects etc.). Note: check the wire size, connection, fuse and other security measures. Grounding lightning protection: install or check the grounding wire or column.
6, electrical load or load or contact: check the low efficiency use of transformer and lamp with a remote control TV power supply is connected to the power; the incandescent lamp black check, consider replacing the halogen lamp or fluorescent lamp; fluorescent lamp to replace the black dust clean; the illuminating lamp and the fixing bracket.
7: check the regulator, inverter, installation, wiring. Note: the charging voltage of the inverter with charging function should be set to 14.5 (29) v. Reference manual. Increase the temperature detector extra if necessary.
8, the temperature of the battery capacity of lead-acid battery in 30 ~ F loss 25%. Full, at the temperature of 20 F ice damage. The summer overheating will also affect their life. So the battery should be avoided in the outdoor temperature under extreme environment. According to the national standard of safe operation of battery can be installed in the room.

Solar power Prospect

Japan plans togenesis. Ready use of the ground area of desert and ocean to generate electricity, and the world through the superconducting cable Solar power station Into a unified power grid to the global supply. According to estimates, to 2000, 2050, 2100, even if the whole solar power with global energy supply but also as an area of 651 thousand and 100 square kilometers, 1 million 867 thousand and 900 square kilometers, 8 million 291 thousand and 900 square kilometers. 8 million 291 thousand and 900 square kilometers accounted for only 2.3% of all marine area or all of the desert is even 51.4%. Sahara Desert 91.5%. So this scheme is possible.
The power generation scheme. As early as 1980, NASA and the Department of energy has proposed building a solar power station in space vision, ready to put a long 10 kilometers wide and 5 kilometers of large flat-panel orbit, covered with solar cells, so as to provide 5 million kilowatts of power. But this need to solve the problem of wireless transmission to the ground. Have been proposed by microwave beam laser beam such as a variety of programs. Model plane with the current implementation has a microwave wireless transmission of short distance, short time, low power, but there is still a long distance away from the real utility.
See from the energy-saving emission reduction targets and the United Nations of the "renewable energy special report" in 2050, to achieve a high proportion of renewable energy alternative is a worldwide trend, it will promote the development of China solar photovoltaic power generation industry. In October 26, 2012, the national Power Grid Corp released "on a distributed photovoltaic power grid service work opinions", greatly reduce the photovoltaic power generation network threshold; the National Energy Bureau pointed out that by 2020 the installed target is 100 million KW, the next few years are more than 10 domestic installed capacity of GW. By 2030 the energy demand reached 50 tons of standard coal in 2050 reached 52 tons, renewable energy accounted for 40% in 2050 the energy demand, electricity demand in renewable energy in the proportion reached 60%, PV installed capacity may reach 1 billion KW. The support of national policy, will promote Chinese solar photovoltaic industry in the rapid and healthy development.
The National Energy Bureau released December 24th "National Energy Bureau Comprehensive Department on the" 13th Five-Year "solar energy development planning work notice", among them, solar thermal power generation is an important content to be mentioned, which means that the thermal power generation will become an important industry in China during the "13th Five-Year" focus on the development of the. The main types of solar energy utilization, including solar photovoltaic and solar thermal utilization, with solar power Electrician The construction conditions of the region, should also include the contents of solar thermal power generation. The planning period of 2016-2020 years, development outlook to 2030. The planning research of solar thermal power generation including: solar thermal power generation and scale, focusing on key areas project The location and conditions, technical route and technical and Economic Research of construction etc.. Solar thermal utilization planning research includes: objectives, key areas, development mode, and promote the application of rural towns and construction measures of solar thermal utilization.
The use of solar thermal project planning includes the research put forward the overall objectives and tasks in 13th Five-Year during the period of solar thermal utilization, put forward building hot water heating, hot water, Air conditioner The classification and development of refrigeration field goals and the layout of the region; to study and put forward technical development roadmap of solar thermal utilization; for high technology research and development, key equipment manufacturing, system integration, system integration and conventional energy and other key aspects, puts forward the development target of technological innovation, implementation of safeguard measures and solutions; analysis and comparison of Chinese and foreign products and the advantages and disadvantages of the competition of manufacturing industry at home and abroad the advantages and disadvantages of the proposed "13th Five-Year" period to enhance industrial competitiveness objectives, tasks and safeguard measures; put forward the "13th Five-Year" period to improve the solar thermal utilization standards, testing and certification system of the task, target and implementation steps, put forward to strengthen quality control, operation and maintenance policies and measures of system construction.
Thermal power generation industry in China during the 12th Five-Year precipitation after gaining, has been basically completed the construction of industry chain and technology accumulation, some enterprises have mastered a certain experience in project development. 2015 is the last year in 12th Five-Year, although we have been unable to complete the original 1GW installed, but with the government to pay more attention to the thermal power generation industry, substantial support policies issued, relying on the existing industrial base, thermal power generation industry in China will usher in the outbreak in 13th Five-Year.
Undoubtedly, the use of solar power photovoltaic power generation technology prospect broad. Solar photovoltaic power generation has nearly unlimited resources, no environmental pollution, is to meet the social needs of the future ideal energy. With the further development of photovoltaic power generation technology, the conversion efficiency increases gradually, the cost of the system becomes more and more reasonable, perfect and distributed generation technology, the smart grid photovoltaic power generation, this green energy will become an important source of energy in the future society.