Audrey Solar Power Station in France is the first solar power station in the world to realize solar power generation.Although the power was only 64 kilowatts at that time, it laid the foundation for the later research and design of solar power plants.
The earliest solar thermal power generation demonstration power station in China is the 70kW tower solar thermal power generation test project in Jiangning District, Nanjing, which was jointly established by Chunhui Company of Nanjing Fiberglass Institute and Weizmann Research Institute in Israel. It was completed and successfully generated power in 2005.During the 11th Five Year Plan periodNational 863 ProgramWith support, 10 units including the Institute of Electrical Engineering of the Chinese Academy of Sciences began to build a 1MW solar tower thermal power experiment project in Badaling, Beijing, which is the first solar tower thermal power technology application project in Asia.By the end of 2010, the power station was connected to the grid for power generation, with an annual power generation capacity of 2.7 million kilowatt hours.
Local governments in Gansu, Shandong, Jiangsu and other provinces have all started the preparatory work for the construction of solar thermal power generation projects and formulated corresponding plans.The largest project in China is the 50 MW slot solar thermal power generation project in Inner Mongolia, which was settled in Balagong Pioneer Zone, Ordos City, Inner Mongolia, and began bidding in June 2011.The major power groups have also begun to actively layout, carry out the preliminary work of solar thermal power generation throughout the country, and reserve a large amount of land for future large-scale expansion.
Equipment
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In 1982, the United States built a 10 million kilowatt tower type solar thermal pilot plant.The United States plans to have solar power stations by 2000[1]The total installed capacity will reach 40 million kilowatts.In 2000 and 2020, the percentage of electricity produced in total energy will be 7% and 25%.Since the photothermal converter (condenser) needs to occupy a large space for daylighting and heating, the equipment is too largeCaliforniaFor example, it is planned to build a 10000 kilowatt power generation equipment. The light collecting device will cover an area of 400000 square meters, and 2 million kilowatts will cover an area of 50 square kilometers.It is estimated that the efficiency of large solar power stations is only about 30%.In addition, solar power stations also need accumulators to meet the power demand at night and in cloudy days, and the required concentrators are also expensive, and the power generation economy is poor, which affects the wide promotion and application.
Maximum power station
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Located in the Mojave Desert on the border between California and NevadaIvanpah Solar Power StationIt is the largest solar power station in the world, covering an area of 8 square kilometers.The power station was opened in March 2017.[2]
The largest solar power station in China will be built in a desert in the west of Dunhuang City, Gansu Province.
The 10 MW solar power plant is the third solar power plant demonstration project approved by the Chinese government. The other two projects are the 255 kW Ordos Project in Inner Mongolia and the 1 MW Chongming Island Project in Shanghai.
However, this 10 MW project with an investment of only 500 million yuan, which will be publicly tendered on March 20, 2009, has attracted 50 photovoltaic enterprises nationwide."The state-owned enterprises include five major power generation groups, including Huaneng and Huadian, as well as private enterprises, such as Wuxi Suntech, and even attract foreign enterprises from Germany and Denmark."
Dunhuang ProjectFranchise rightsThe National Development and Reform Commission has a series of policies to ensure the profitability of the project."This project may be formulated for the next stepPhotovoltaic power generationProvide basis for policy.Who gets this project means that he or she will get the first mover advantage in policy and experience in the future. "Industry insiders said that the completion of this project may really activate the domestic market of photovoltaic power generation and change the pattern of both ends outside.
The solar cell module is the core part of the power generation system. Its role is to directly convert the solar radiation energy into direct current for load use or storage in the battery for backup.Generally, according to the user's needsSolar panelConnected in a certain way to formSolar cell array(array), together with appropriate support and junction box, to form a solar cell module.
2．Charging controller
In the solar power generation system, the basic function of the charging controller is to provide the best charging current and voltage for the battery, charge the battery quickly, stably and efficiently, and reduce the loss during the charging process to maximize the service life of the battery;At the same time, the battery shall be protected to avoid overcharge and over discharge.Advanced controller can record and display various important data of the system at the same time, such as charging current, voltage, etc.The main functions of the controller are as follows:
(1) Overcharge protection prevents the battery from being damaged due to high charging voltage.
(2) Overdischarge protection prevents the battery from being damaged due to discharging to a low voltage.
(3) Anti reverse connection function to avoid battery andSolar panelBecause the positive and negative poles are connected, they cannot be used or even cause accidents.
(4) Lightning protection function can avoid damaging the whole system due to lightning stroke.
(5) Temperature compensation is mainly aimed at places with large temperature difference to ensure the best charging effect of the battery.
(6) The timing function controls the working time of the load to avoid energy waste.
(7) Overcurrent protection automatically cuts off the load when the load is too large or short circuited to ensure the safe operation of the system.
(8) Overheat protection When the system operating temperature is too high, it will automatically stop supplying power to the load. After troubleshooting, it will automatically resume normal operation.
(9) Automatic identification voltage For different system operating voltages, automatic identification is required without additional settings.
3．Battery
The purpose of the battery is toSolar cell arraySend out DC power and store it for load use.In photovoltaic power generation system, the battery is in floating charge discharge state.During the day, the solar cell array charges the battery, while the array also supplies power to the load. At night, all the load power is supplied by the battery.Therefore, it is required that the self discharge of the battery should be small, and the charging efficiency should be high. At the same time, factors such as price and convenience of use should be considered.
4．inverter
Most electrical appliances, such as fluorescent lamps, televisions, refrigerators, electric fans and most power machines, work on AC power. In order for such appliances to work properly, solar power generation systems need to convert DC power into AC powerPower electronic equipmentIt is called inverter.The inverter also has the function of automatic voltage stabilization, which can improve the power supply quality of photovoltaic power generation system.
computing method
Taking 100W output power for 6 hours a day as an example, the following calculation method is introduced:
1. First, calculate the watt hours consumed per day (including the loss of inverter): if the conversion efficiency of inverter is 90%, when the output power is 100W, the actual required output power should be 100W/90%=111W;If it is used for 5 hours a day, the power consumption is 111W * 5 hours=555Wh.
2. CalculationSolar panel: The output power of the solar panel shall be 555Wh/6h/70%=130W based on the daily effective sunshine time of 6 hours and taking into account the charging efficiency and the loss in the charging process.70% of which is the actual power used by the solar panel during the charging process.
3. Selection of charging controller: the maximum output current of 130W solar panel is 7.7A.Therefore, a charging controller with a charging current of at least 8A should be selected.
4. Selection of storage battery: if 12V storage battery is used and its discharge depth is 50%, 555Wh/12V/50%=90Ah storage battery shall be used;If 24V battery is selected, its capacity shall be 555Wh/24V/50%=45Ah.
Estimation and detection
Solar cellRated output powerAndconversion efficiency In general, the higher the conversion efficiency, the greater the output power of the battery module per unit area.The conversion efficiency of solar cells is generally between 14~17%, and the output power of each square centimeter of cell is between 14~16mWSolar cell moduleThe output power is about 120WP
Solar cell moduleSpecial testing equipment shall be used for testing under standard conditions.Because the detection equipment is very expensive, the general detection method is to use iodine tungsten lamp or incandescent lamp to simulate sunlight and compare the samples for comparative test, mainly to detect their open circuit voltage and short circuit current. Pay attention to control the temperature during detection, which cannot exceed 25 ℃.
Basic calculation formula
Power=voltage X current (W=UI) Power consumption=power X time (Q=Wh)
Precautions for power generation
Solar photovoltaic power generationVarious factors need to be considered comprehensively. Only after accurate data are mastered can the installation mode, minimum power, specification of the solar panel (the daily effective power generation of the solar panel must be too much than the load power consumption) and the capacity, performance and control mode of the battery be determined.Make the product reach the best cost performance ratio.If the estimation of relevant factors is wrong, it will directly affect the performance and cost of independent photovoltaic power generation system.
(1) Geographic location of the site.
Including: location, latitude, longitude, altitude, etc.
(2) Meteorological conditions at the installation site.
Including: monthly total solar radiation, direct radiation (or percentage of sunshine), annual average temperature, the longest continuous rainy days, maximum wind speed, hail, snow and other special meteorological conditions.
(3) Maximum load.
Including: daily working time and average power consumption of load, and working time in continuous rainy days.
(4) Load power consumption characteristics
Since the output current of the solar cell array is DC, if the load is AC, it needs to be converted by the inverter to work normally, so that the energy loss of the final load supplied by solar energy will increase, thus the required solar cells will increase, leading to an increase in the cost of the solar power supply system.
(5) Requirements of AC load on power supply
AC load requires moreSolar panelIn addition, the requirements for inverter will also vary with different loads.Generally speaking, load with pure resistance, such as heating wire, does not have high requirements for inverter, so ordinary correction wave inverter can be used.However, TV and motor have relatively high requirements for power supply, which requires high inverter power and output characteristics. High power sine wave inverter is required to ensure normal operation of load without interference.The cost varies with the load requirements.
(6) Restrictions on use
Because some countries and regions have specific environmental requirements for batteries, especially nickel cadmium batteries in Europe and the United States are strictly restricted, and lead-acid batteries will also be restricted in transportation, these factors will lead to an increase in the cost of solar photovoltaic products.
General requirements for products
(1) Waterproof, hail proof and wind proof.
commonlySolar paneluseTempered glassThe outer frame is sealed with aluminum alloy, which can effectively resist the hail attack. The installation is fixed with a metal bracket, which can withstand the gale above level 10.
(2) Sun protection and anti freezing.
Generally, there are ventilation and heat dissipation windows to facilitate the heat dissipation of the battery.For particularly cold areas in winter, anti solidification gel batteries are used.
(3) Control protection
In order to maximize the service life of the battery panel and battery, there are generally anti reverse charge, overcharge, and over discharge protection circuit controls to avoid damage to the battery panel and premature aging of the battery.
(4) Part selection
Due to the different use environment of solar photovoltaic products, the temperature difference is large, so the operating temperature range of parts is required to be wide.
(5) Maintenance
The solar cell power generation system has no moving parts and is not easy to be damaged. Its maintenance is also very simple.However, regular maintenance is also required, otherwise normal use may be affected, or even the service life may be shortened.
In general, the inclination of the array of solar panels should exceed 30 degrees, and all dust can be cleaned by rain. In areas with heavy wind and sand, dust should be removed frequently to keep the array surface clean, so as not to affect the power generation.Dust can be wiped off when cleaning, and clean with clean water when conditions permit, and then wipe dry with clean cloth.Do not use corrosive solvents or hard objects to wash and wipe.Regularly check the tightness of all installed parts.In case of hail, gale, rainstorm and other abnormal weather, protective measures shall be taken in time.Check the charging and discharging of the battery frequently, and observe whether there is corrosion or poor contact in the electrode or wiring at any time.
In some simple systems, the power consumption shall be controlled according to the energy storage condition to prevent the battery from being damaged due to over discharge.If any abnormality is found, it shall be checked and repaired immediately.
Questions to be clarified in application
1. Solar cell peak power
A common problem is that as long as there is sunlight, the rated power can be output. The peak power of 100WP can generate 1000WH, that is, 1 kilowatt hour of electricity, if it is irradiated for 10 hours under ordinary lighting conditions. In fact, the solar peak power WP is under standard conditions: radiation intensity of 1000W/m, air quality of AM1.5, and battery temperature of 25 ℃,The output power of the solar cell.(This condition is about the same as the sunshine conditions around noon on sunny days.) According to the sunshine conditions in Guangdong, the standard sunshine time is about 3.3~3.5 hours.In rainy days, the solar cell can also produce certain energy, and its power is about 5-15% of the rated power
2. Solar power generation loss
It is usually mistaken for:Solar cell moduleThe power output every day will be fully utilized by the load.In fact, there is a considerable loss in the installation of solar cell modules, about 15-20%. During charging and discharging, the loss is about 20%. If there is an inverter, the loss is more than 10%. In general, the utilization rate of solar power generation is about 50%.In short, all energy conversion processes must follow the law of energy conservation, and will never be created out of nothing, nor will it be used 100%.
3. How to reduce solar power loss
Generally speaking, in order to reduce the loss as much as possible, the following measures are often taken:
⑴Solar cell moduleTilt, perpendicular to the light, generally 35~40 degrees in Guangdong.
⑵ Open circuit voltage, short circuit current, working voltage, working current and other parameters of all solar cell components
The number shall be as consistent as possible, and the connecting cable shall be as thick and short as possible.
⑶ If the battery is in series, the internal resistance of all cells shall be as consistent as possible and as small as possible.
⑷ In order to reduce the loss between lines, if conditions permit, the scheme of high voltage and low current shall be adopted as far as possible, so as to make the current borne by the line as small as possible, thus reducing the loss.When designing the control circuit, components with high integration and good stability shall be used as far as possible.
Benefit comparison
With the increasing scarcity of the earth's resources and the increasing investment cost of basic energy, various security and pollution hazards can be described as ubiquitous.Solar energy, as a kind of "inexhaustible, inexhaustible" safe and environmentally friendly new energy, has attracted more and more attention.In this way, solar lighting productssolar heaterAfter popularization, we should be born. Here we aresolar light The utility model is compared with the effect of using mains lamps.
*Contrast 1
The installation of municipal lighting fixtures is complex: there are complex operating procedures in the municipal lighting fixture project. The first step is to lay cables. Here, a large number of foundation works such as cable trench excavation, laying of concealed pipes, threading in pipes, backfilling, etc. will be carried out.Then the installation and commissioning shall be carried out for a long time. If any line is faulty, it shall be reworked in a large area.Moreover, the terrain and route requirements are complex, and the cost of labor and auxiliary materials is high.
High electricity cost of municipal lighting fixtures: there is a fixed high electricity cost in the work of municipal lighting fixtures, and the lines and other configurations should be maintained or replaced continuously for a long time, with the maintenance cost increasing year by year.
Solar lighting is free of electricity charge: solar lighting is a one-time investment, long-term benefit, and low maintenance cost.
*Comparison III
The utility lighting has potential safety hazards: due to the construction quality and landscape engineering of the utility lighting
There are many potential safety hazards in the aspects of engineering transformation, material aging, abnormal power supply, water and electricity pipeline conflict, etc.
Solar lighting has no potential safety hazard:solar light It is an ultra-low voltage product with other advantages of safe and reliable operation of solar lighting: green and environmentally friendly, which can add new selling points for the development and promotion of noble ecological communities;Continuously reduce property management costs and reduce the expenses shared by owners.To sum up, the solar lighting is safe, energy-saving, environment-friendly, easy to install, and maintenance free for automatic control.
Operation process
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domesticPhotovoltaic power stationFrom project approval to design to construction---Grid connected operationThe whole process, and with description.Since how to effectively control costs and improve profitability is the core concern of investors, the first phase construction cost of photovoltaic power station investment project naturally becomes the focus.As a long-term operation and investment project, the reliability of the overall photovoltaic power generation system for 25 years of stable operation should be paid more attention.
