Solar-related knowledge

Polaris solar PV net news: 1. What are the uses of solar energy?

Solar energy is different from any other kind of special energy. The use of solar energy are: ① photovoltaic (solar cells, solar cells) generation system converts solar energy into electricity; II the solar thermal power systems, solar thermal energy produce electricity ③ thermal use of solar energy, such as solar hot water system about solar heating, solar air conditioning, heating and cooling, solar building. “Shinin” solar-powered aircraft of this type of application of future mobile energy is photovoltaic power generation system, planes take off, landing and flying all sources of power, electricity comes from solar photovoltaic systems.

2. What is solar power? What is a distributed PV?

Photovoltaic power generation refers to the use of solar PV cells transform solar radiation directly into electricity generation. Photovoltaic is the mainstream of solar power, so now it is usually said that refers mainly to the photovoltaic solar power generation.

Distributed solar power, refers to the building near the venue where your users reside, spontaneous use of run as user-side, excess electricity Internet and distribution system characterized by a balance of photovoltaic power generation facilities.

Distributed PV followed suit measures to local conditions, clean, efficient, decentralized principles of layout, nearest, making full use of local solar resources, alternative and reducing fossil energy consumption.

Do you know the historical origin of photovoltaic power generation?

· In 1839, the 19 year old France becquerel when making an experiment in physics, found in two metal electrodes in conductive liquid when the light shines, current will be stepped up, so as to find the “photovoltaic effect”;

· In 1930, Lange first proposed using “photovoltaic effect” manufactured “solar cells”, make solar energy into electrical energy;

· In 1932, Stowe and aodubote made the first “CDs” solar cells;

· In 1941, Orr found on Silicon photovoltaic effect;

· In May 1954, United States Bell Labs Pirson and Philippines, fuller developed a monocrystalline silicon solar cells with efficiency of 6%, which is the world’s first practical silicon solar cells. The same year, Wicker was first discovered the photovoltaic effect of gallium arsenide and cadmium sulfide thin films deposited on glass, made of solar panels. Converting solar energy to electricity practical photovoltaic technology was born and developed.

In 1954, the United States Bell laboratory

United States Bell Labs made the first solar cell

4. How does photovoltaic cells generate electricity?

Photovoltaic cell is a kind of light-electricity conversion characteristics of semiconductor devices, which directly convert solar radiation into direct current, is the most basic unit of photovoltaic power generation. Photovoltaic cells in crystalline silicon electrical characteristics is unique thanks to some mixed in elements (such as p or b, and so on), the molecules in the material cause permanent imbalance in charge, formed with special electrical properties of semiconductor materials. In the sunlight, with special electrical properties of semiconductors can produce free of charge, these free charges moving and accumulating, which formed on the ends of the electromotive force, when conductors will be closed at both ends, it produces electricity. This phenomenon is known as the “photovoltaic effect”, the abbreviation “photovoltaic effect”.

Schematic diagram of solar power generation

5. what parts of a PV power generation system consist of?

Photovoltaic power generation system consists of photovoltaic (photovoltaic array formed by the PV module and parallel), controller, batteries, DC/AC inverters and other components. Photovoltaic power generation system is the core component of PV modules, PV modules is formed by the PV series and parallel and package, it will be Sun’s energy directly into electricity. PV modules generate electricity to DC, we can directly use, can also be converted into alternating current of the inverter before use. From another perspective, photovoltaic systems produce electricity can be used, batteries and other energy storage devices can also be used on the energy stored and released as you need to use, its system components as shown in the following figure:

Schematic diagram of solar photovoltaic power generation system

6. Why say PV power is green and low-carbon energy sources?

PV has significant energy resources, environmental protection and economic benefits, is one of the highest quality green energy. Average sunshine in China under the condition of installing 1-kilowatt distributed PV systems, 1 may issue 1200 kilowatt-hours of electricity to reduce coal (coal equivalent) uses about 400 kilograms, about 1 ton reduction in carbon dioxide emissions.

According to the World Wildlife Fund (WWF) results from the effect of carbon dioxide emissions, installing 100 square meters of photovoltaic power generation system is equivalent to 1 square meter afforestation. At present, the development of photovoltaic power generation renewable energy is going to be solved, such as haze, acid rain and other environmental problems as one of the effective means.

7. What are the advantages of photovoltaic power generation?

① inexhaustible solar energy resources inexhaustible.

Secondly, green. Photovoltaic power generation does not need fuel, no carbon-dioxide emissions, and does not pollute the air. Does not produce noise.

③ wide application range. As long as I can get light where you can use solar power systems, it is not affected by geographic location, altitude and other factors.

④ no mechanical moving parts, operation, maintenance is simple, stable and reliable operation. A photovoltaic system as long as there is Sun, solar panel will power, and now are used in automatic control, without manual operation.

⑤ rich materials for solar cell production: Silicon is abundant, and abundance in the Earth’s crust after oxygen, in second place, reaching as much as 26%.

⑥ and long service life. Crystalline silicon solar cells can live for 20-35 years. In photovoltaic systems, as long as reasonable design, selection of appropriate, battery life can be as long as 10 years.

⑦ solar modules is simple in structure, small size and lightweight, easy to transport and install, short construction periods.

⑧ systems easy. Some monomers are combined into solar modules and battery system’s solar array and battery; inverters, controllers can also be integrated. System can be big or small, and easy scalability.

Energy recovery period is short, about 0.8-3 years; energy multiplier effect obvious, about 8-30 times.

8. What reports said “production consume a lot of energy when the solar module” message?

Photovoltaic cells consumes a certain amount of energy in the production process, in which Silicon purification of high-purity polycrystalline silicon, monocrystalline silicon rods/polycrystalline silicon ingots produced three aspects of high energy consumption. But the use of photovoltaic cells in 20 lifetime can continue to produce energy. It is estimated that the average in our country under the condition of sunlight, photovoltaic power generation system life-cycle energy return over 15 times, more than double its energy consumption. In Beijing the optimum angle of 1-kilowatt rooftop photovoltaic systems installed energy recovery period is 1.5-2 years, far less than the period of the life of the PV system. In other words, 1.5-2 years before the PV system’s power is used to offset its production processes, such as energy consumption, 1.5-2 years later of the energy delivered is pure energy. So, from the perspective of life cycle energy consumption evaluation of photovoltaic cells.

9. How do I look at reports that “produce solar modules generate a lot of pollutants” message?

Solar module production consists of high purity polysilicon ingot, silicon wafers, PV cells and PV industry chain link. Reports related to contaminated refers mainly to the PV module of the raw material in the production of high-purity polycrystalline silicon by-products. High purity polysilicon production using mainly modified by Siemens, which metallurgical grade silicon into three hydrogen Silicon chlorine plus hydrogen into solar-grade polycrystalline silicon and Silicon tetrachloride by-product will form. Silicon tetrachloride is contact with humid air is decomposed into silicic acid and hydrogen chloride, if not handled properly can cause pollution problems. But the improved Siemens process polysilicon production enterprise could already be closed cycle production, Silicon tetrachloride by-product and exhaust gas (hydrogen and chlorine), recycling, clean production. In December 2010, the State released the conditions of polysilicon industry access, provisions restored silicon, hydrogen chloride, hydrogen chloride in tail gas recycling rate of not less than 98.5%, 99%, 99%. Therefore, the mature modified Siemens production technology to meet environmental requirements and does not produce pollution.

10. how many of us can take advantage of the Sun? It could well be the future energy?

Receive solar radiation to the Earth’s surface to meet global energy needs 10,000 times. Surface per square meter received radiation between approximately 1000-2000kWh per year on average. International Energy Agency data shows that install photovoltaic systems in the 4% desert in the world, would be sufficient to meet global energy demands. PV has a broad development space (roofs, buildings, open spaces and desert, etc), have great potential.

According to preliminary statistics, using only the existing roof of the installation of distributed PV in our country, its market potential is about 300 million-kilowatt above, coupled with the vast desert in the West, photovoltaic market potential is estimated at billions of kW or more. With technology and large-scale application of photovoltaic power generation, electricity costs will be further reduced and become more competitive ways of energy supply step by step from the supplementary energy transition to alternative energy sources, and is hopeful to become the dominant energy in the future.

11. solar energy resources are distributed in China?

Solar radiation in China is rich in resources, presented “plateau is greater than the dry western plains, humid region is larger than the Eastern District” of distribution. Among them, the most abundant on the Tibetan plateau, the annual total amount of radiation more than 1800kWh/m2, even 2000kWh/m2 in some areas. Resources in Sichuan basin is relatively low, there is lower than the 1000kWh/m2 area.

Total solar radiation levels nationwide and regional distribution tables

National horizontal global solar radiation chart

12. agricultural greenhouses, ponds you can install the distributed grid-connected PV system?

Greenhouse “warming up, holding” the key issues has always been a problem for farmers. “PV farm greenhouses”, is expected to solve the puzzle. Due to summer of high temperature, in 6 ~ September many category of vegetable cannot normal growth, and “PV agricultural big shed”, like in agricultural big shed appearance filled has a points light meter, can isolated infra-red, block too much of heat entered big shed; in winter and night of when, is can block big shed within of infrared band of light to outside radiation, reduced night temperature fell of speed, up to insulation of role. “Solar PV farm shed” can supply power of agriculture greenhouse lighting, surplus electricity grid. In the form of off-grid “PV farm shed”, and LED systems deployed, blocking light and plant growth during the day, while power generation; the night LED systems use electricity generated during the day and lights.

In fish ponds can also set up photovoltaic arrays, can continue to fish in the pond, PV array can also provide good shelter for the fish, can resolve the development of new energy-and land-intensive conflicts. Therefore, agricultural greenhouse and ponds distributed PV systems can be installed.

The National Energy Board issued the notice on further implementation of distributed photovoltaic-related policies clearly stated “encourages various forms of distributed PV applications. Encourage local governments at all levels in State-subsidized matching based on finance subsidy policy, and public institutions, and affordable housing and increasing support in the countryside. The use of abandoned land, barren slopes, beaches, ponds, lakes, agriculture greenhouses, such as building local absorptive distributed photovoltaic power plant. ”

13. What is the “PV benchmark price” policy?

“PV benchmark price” policy is based on the current cost of photovoltaic power generation, electricity prices in developed after taking into account a reasonable profit, PV project developers at this price of photovoltaic electricity sold to the grid companies, of which higher local desulfurized coal-fired thermal power plant Internet difference to take the benchmark rate “network-wide assessment” approach to cover the grid companies. “PV benchmark pricing” policies mainly for large photovoltaic power plant in the early, current can also be applied to distributed PV projects.

14. How do I obtain a solar resource data?

Country exposure and sunshine hours as shown in the following figure, if you want to get more details about the solar resource data available from county-level meteorological stations (stations), the national weather service public weather services centre; also available from large installers or design units or from the official NASA website (https://eosweb.larc.nasa.gov/sse/RETScreen/) to gain exposure reference data.

15. the decision of a PV array setup inclined?

Installation of a PV array installation angle of the main geographical longitude, latitude, and the best exposure decisions, due to the installation conditions, component installation inclination angle can be adjusted when you can’t achieve the best, non-South-facing roof generating capacity will have a serious impact.

Tables: best major cities nationwide PV modules installation angle

16. the PV array installation how to determine? The impact on power generation effect?

Due to the factors affecting the PV for sunshine, so components should be installed to the sunniest orientation. Different setting angles on power generation efficiency photovoltaic modules are also affected. Figures show China’s southern city of PV modules under various different efficiencies. (Note: different places and under different climatic conditions and different orientation is different from photovoltaic power generation efficiency. )

17. How can I use PV modules?

Under specific circumstances you can choose different types of installation site, different specifications of the PV modules, installation size determines the size of components of effective use, per acre to install higher capacity, optional high efficiency component. Based on the appearance of the existing buildings, or you can choose a different border color of components, according to length of series-parallel connection mode determines the component connectors.

Selection of components, need to consider the mounting area, capacity, cost and other factors. In General should choose good reputation, quality, certification, warranty good after-sales service, fire-proof, certification component of the product.

18. the thin-film PV module features are there?

Answer: the preparation of thin film PV modules due to its unique technology, which has the following characteristics:

(1) PV module temperature characteristics. Due to the dynamic changes of temperature, solar module conversion efficiency at different temperatures in different, higher working temperature, PV module conversion efficiency is low. Thin-film PV modules compared to crystalline silicon PV module temperature coefficient is small, so as the temperature rises, thin-film PV module power is reduced to a lesser degree, so the thin-film PV modules applies to buildings with more excellent power output characteristics.

(2) the weak light characteristic of the photovoltaic modules. Low intensity of solar radiation, such as mornings, evenings and rainy days, due to the high optical absorption coefficient of thin-film photovoltaic cells, especially when the PV modules used on buildings, installation conditions, subject to certain restrictions, installed in most cases is not the optimum tilt angle, and components under the influence perimeter shadow is large, thin-film PV module capacity advantages will be more obvious.

(3) thin film PV modules prepared by coating on the glass substrate generation film, and then laser engraved process divides the film into several modules strung together battery and battery and subcell line width between Visual easy to appear and, therefore, constitute the photovoltaic curtain wall with good color consistency and uniformity of light.

(4) structural design of thin-film photovoltaic modules can form a hollow structure, the hollow structure, with its unique power coating can achieve high performance thermal insulation and energy-saving function.

19. the thin-film PV modules applies to have any special advantages on the roof?

Domestic roofing is generally divided into flat roof, sloping roof and roofing with the radian, thin-film photovoltaic modules applied to building roof has the following advantages:

(1) due to the thin-film photovoltaic modules with excellent low light output characteristics, while in indirect sunlight with the reflected and scattered light can still guarantee greater power output, so the thin-film PV modules has a strong ability to adapt to different directions to install.

Thin-film photovoltaic modules with different roof-mounted cases

(2) due to the thin-film PV modules can be designed with lightweight construction, such as flexible CIGS module, so at the time of installation for the lower roof load restrictions, can be installed on a roof in poor load-bearing capacity.

(3) on the roof with radian, flexible flexible PV modules can be used (such as flexible CIGS module), the fine combination of PV modules and roof to reduce wind pressure effects.

20. PV system what are the common faults? System components typical problems which may occur?

Because the voltage has not reached startup settings cause the inverter to work, will not start, due to components or inverter causing low power; system components typical problems that may occur with junction box burned, component part burned to the ground.

21. how to deal with common faults of photovoltaic power generation system?

System if a problem occurs during the warranty period, first telephone installation note on business or operation and maintenance of business system, installers or operation and maintenance of the Chamber of commerce based on user content solutions, such as fault could not be ruled out sending someone on site to carry out maintenance.

22. how long is the life span of a distributed building photovoltaic systems?

Under normal circumstances, building of photovoltaic power generation system design life span of 25 years, unable to meet with the life-cycle of the components should be easy to repair, replacement.

During design time, design working life of two considerations:

(1) the additional roof PV systems structural design working life of not less than 25;

(2) other than additional roof PV system architecture in the form of photovoltaic systems (for example, photovoltaic roof and PV photovoltaic curtain wall Windows, solar shading, solar rail etc) the supporting structure and its design life of the structure should not be smaller than the alternative design working life of building components.

23. lead to decreased efficiency of photovoltaic power generation system and what are the main factors of the loss?

Efficiency of photovoltaic power generation system lose out from any outside influence, including shielding attenuation, temperature effects, ash layer, component, component matching, accuracy of MPPT, inverter efficiency, loss of efficiency of the transformer, DC and AC circuits and so on, as shown in the following figure:

Each of these factors have different effects on efficiency, projects should pay attention to system optimization design, project running to take some measures to reduce dust blocking effect on the system.

24. How can I reduce the maintenance cost of photovoltaic power generation system?

Recommended that you choose a good reputation in the market of PV products, good after-sales service. Qualified products can reduce the incidence of failure, the user should strictly abide by the system product manual, periodic inspection and cleaning and maintenance of the system.

25. system maintenance how to deal with, how long to maintain once? How to preserve?

According to the supplier’s manual for parts that require regular inspections for maintenance, system maintenance is to wipe components, rainwater larger districts generally do not need to manually clean, non-clean once rain season is about 1 month. Dust large regions may, where appropriate, increasing the frequency of wiping, snow heavy snowfall areas should timely be removed, to avoid affecting the power generation and produces non-uniform block after the snow melts, cleared trees or debris shielding components.

26. thunderstorms need to disconnect the PV system?

Distributed PV systems are equipped with lightning protection device, so you don’t have to disconnect. In order to secure insurance recommended can choose to disconnect the combiner box circuit breaker switch, disconnect electrical connection of the PV modules, avoiding direct lightning stroke of lightning protection module cannot remove hazard. Operations staff should be timely detection of lightning protection module, in order to avoid lightning protection module failure arising out of harm.

27. after the snow needed clearing PV system? PV modules in the winter snow melt freezing up how to deal with it? Clean the tread above the component work?

Components if accumulated after snow heavy snow is needed to clean and push snow down your can take advantage of the soft, be careful not to scratch the glass. Components have a certain weight, but you can’t tread above components cleaning can cause cracked or damaged components, component life. Generally not recommended to clean up too thick with snow, so as to avoid excessive components from freezing.

28. PV system resists hail damage it?

PV grid-connected system of qualified components must be positive in the maximum static load (wind load, snow load) 5400pa, maximum static load on the back (wind load) 2400pa and 25mm in diameter hail impact and other rigorous testing with 23m/s speed. So hail photovoltaic systems will not be harmful.

29. after installation if rain or fog, and photovoltaic power generation system will work? Lack of will power or power?

Under certain low light, solar modules can be powered, but due to continuous rain or smog, solar irradiance is low, the operating voltage of the photovoltaic system if the starting voltage of the inverter, the system will not work.

Grid-connected distributed photovoltaic power system and distribution network are operating in parallel, distributed PV systems do not meet the load requirements, or not working due to a cloudy, the electrical grid is automatically added, there is no issue of power shortages and power outages.

30. winter would power shortage in cold weather?

PV system’s output from the effects of temperature, direct influence factors of radiation intensity and long sunshine hours and the working temperature of the solar modules. Winter radiation intensity will inevitably weaker, sunshine duration will be shorter, generally generating capacity less than summer, which is a normal phenomenon. But due to distributed PV systems associated with the grid as long as grid electricity, household loads will no longer be power shortages and blackouts.

31. the photovoltaic power generation system: electromagnetic radiation hazards to users?

Photovoltaic power generation system is based on the photovoltaic effect to convert solar energy into electricity, no pollution, no radiation. Electronic devices such as inverters, power distribution cabinet by EMC (electromagnetic compatibility) tests, and therefore is not harmful to the human body.

32. the photovoltaic systems do you have noise?

Photovoltaic systems convert solar energy into electricity without noise impact, the inverter does not exceed 65 decibels of noise indicators, there will be no danger.

33. the licensed solar PV system in our country and quality of product testing and certification bodies are there?

Certification bodies are: Beijing Jian Heng certified centers, China quality certification center and the China building materials inspection and certification group.

Testing institutions mainly include: Institute of solar photovoltaic systems and wind power generation system for quality examination Center, national solar photovoltaic products quality supervision and inspection center, Institute of China electronic technology group Corporation 18th, Institute of China Aerospace Science and Technology Group Corporation No. 811, Shenzhen electronic product quality test center, optoelectronic products testing center in Yangzhou, China National building materials industrial solar (electric) products quality supervision and inspection center, and so on.

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