Solar power, it is a power generation system that converts the radiant energy of sunlight into electrical energy, utilizing photovoltaic cells made of semiconductor materials to generate photovoltaic effects and directly convert solar energy into electrical energy.
Solar photovoltaic power generation systems are composed of solar panels, solar controllers, batteries, solar inverters. solar cable, LV DC power cables, MV AC power cable, step-up or step down distribution transformer , or a pad mounted transformer need to be used, cable raceway, electrical switchgear and even fiber optical cables etc. There are two types of solar power generation systems: grid-connected solar power generation systems and independent solar power generation systems, which have the characteristics of environmental protection and low-carbon. However, the cost and economic benefits of different types of solar power generation systems vary greatly.
In March 2022, the global cumulative total installed capacity of solar power has crossed the threshold of 1 terawatt, officially entering the “terawatt level era”. The price and installation cost of solar power continue to decline, and solar power are widely used in the fields of new energy and manufacturing.
Solar power is one of the main players in the clean energy industry, solving the high carbon emissions and unsustainable issues of fossil energy power generation, and promoting the transformation and upgrading of the global energy economy.
History of solar power
In 1839, French scientist Becquerel discovered that light can enhance the current of two metal levels in conductive liquids, resulting in the photovoltaic effect, which laid the physical foundation for the development of the solar power industry.
In 1954, American scientists Chapin and Pearson created the first practical monocrystalline silicon solar photovoltaic cell at Bell Labs, and the photovoltaic power generation technology of converting solar energy into electricity was also born.
In the 1960s and 1970s, solar cells began to enter the fields of space applications and ground applications. The impact of the two subsequent oil crises made photovoltaic power generation highly valued globally and an alternative to conventional energy. Developed countries in Europe and America introduced photovoltaic industry support policies to encourage and support the development of solar technology, and China in Asia also began to research solar power generation technology, The global solar power industry has ushered in a period of development opportunities. Solar power generation technology has been widely applied in the civilian market, and a large number of solar power generation systems have been installed globally. The applications of these systems are mainly concentrated in fields such as communication, pipeline protection, traffic signals, and power supply in remote areas.
Since the 1980s, solar cells have maintained a development rate of 15% to 25%. Countries around the world continue to promote the development of solar cell technology, and the conversion efficiency of solar cells continues to improve. The types and application scope of solar cells have also increased, leading to the emergence of applications such as silicon based solar cells and thin film solar cells.
The period from 2000 to 2008 was the first stage of rapid development in the global solar power industry, with high subsidies and increased market demand leading to rapid expansion of photovoltaic production capacity in Europe, America, and China.
From 2008 to 2009, the subprime mortgage crisis broke out, and the demand for solar power installation in the international market significantly shrank. European and American photovoltaic enterprise giants went bankrupt and went bankrupt one after another. However, China’s first generation photovoltaic enterprises, relying on the European and American photovoltaic market and imported polycrystalline silicon raw materials, also faced the risk of losses and bankruptcy due to the sharp rise and fall in polycrystalline silicon material prices, and ultimately withdrew from the international photovoltaic market.
After the subprime crisis, the solar energy industry in Europe and America has not recovered production capacity, while China in Asia has completed the iterative upgrading of raw materials, technology, and market in the photovoltaic industry chain, achieved domestic substitution, and opened up the Southeast Asian market. The European Union and the United States have gradually relied on China’s solar power industry chain for photovoltaic product production, and China ultimately dominates the global photovoltaic industry.
In 2020, the global solar power industry ushered in a carbon neutral era. Under the global consensus on carbon neutrality, China, the United States, the European Union and other countries have continuously increased the installed capacity of solar power generation systems, increased the proportion of photovoltaic power generation, achieved affordable grid access, and transitioned to a new energy economy.
The solar power generation system consists of solar cell components, solar controllers, battery energy storage devices, inverters, power cables, distribution transformers, electrical switchgear and other load terminals, etc.
The solar cell module and battery energy storage device constitute the power supply system; The controller and inverter form a control and protection system; DC load and AC load constitute the system terminal.
Materials composed in a solar power plant
Solar cell module
Solar cell modules, also known as solar panels, are the smallest units in the photoelectric conversion process. They are connected in series and parallel, and packaged to form a solar cell module that can be used as a separate power source.
The energy generator of a solar power generation system is called a solar cell array, which is formed by connecting solar cell modules in series and parallel, and encapsulating them on a bracket.
solar controller
The solar controller is an automatic control device that prevents excessive charging and power generation of batteries, adjusts the depth of charging and discharging, and thereby improves the service life of battery cycling charging and discharging.
Battery energy storage device
Energy storage equipment is the key to solving the intermittent and fluctuating nature of solar power generation. When there is sufficient sunlight during the day, excess electricity can be stored through batteries. When there is no solar energy at night, the electricity stored by batteries during the day can be used, so more & more battery energy storage system is used in these independent PV power plants.
solar inverters
Solar Inverter is the abbreviation of power electronic converter, which is a device that can convert direct current into alternating current. The electricity generated by solar power generation systems is direct current, while the electricity used by residents in their daily lives is alternating current. Inverters are indispensable and important supporting equipment for solar power generation systems.
Power cables
Photovoltaic cables refer to cables used for electrical energy transportation, which are used in the DC side circuit system of solar photovoltaic power plants. They have characteristics such as cold resistance, high temperature resistance, flame retardancy, environmental protection, and UV protection. except this PV cable, there still need a lot of low voltage DC power cable, medium voltage power cable to connect each solar inverters; and also, it may some bare aluminum conductor, ACSR and OPGW cable if it need to build up a new power transmission line to connect solar power plant into local Grid network.
Load terminal electrical equipment
The load end of photovoltaic power generation refers to the output side that consumes current. Through the regulation of the inverter, the electricity generated by solar power can be prioritized for use by the load, and it can be transmitted to the power grid if it is not used up at the load end.
Working principle of a solar power plant
Solar power generation utilizes the photovoltaic effect at the semiconductor interface, which refers to the phenomenon of potential differences between semiconductors or metal combinations exposed to light or other electromagnetic radiation. This is also a technology that directly converts light energy into electrical energy, and the key component of this technology is solar cells.
A solar cell is a semiconductor photodiode. When sunlight shines on the photodiode, the photodiode converts solar energy into usable electrical energy. The energy conversion process of photovoltaic power generation actually utilizes the photovoltaic effect, first converting photons into electrons, that is, converting light energy into electrical energy, forming a voltage. With the voltage, the two are connected to form a current circuit, emitting green electricity.
The solar cell array and solar controller are on the input side of the photovoltaic circuit, while the battery, inverter, and load are on the output side. Solar cells generate direct current energy, which enters the load end of the output side through the controller and photovoltaic cable for use at the DC load end; If it is an AC load in the urban area, it needs to be converted into AC power through an inverter, regulated and boosted by a transformer, and transmitted to the AC load end of the power grid for use by thousands of households; The direct current energy generated by the solar cell can also be regulated by the solar controller and fed into the output side battery to store the electricity as a backup power source.
When the photovoltaic and public grid are connected for power generation, the battery is in a charging state, and when the grid malfunctions, the battery can provide power to maintain the operation of the photovoltaic system.
Types of solar power plant
grid-connected solar power system
Grid connected solar power generation system refers to a solar power generation system where the direct current generated by solar modules is converted into AC power that meets the needs of the municipal power grid through grid connected inverters, and then directly connected to the traditional power grid system.
According to whether there is a battery or energy storage system, grid connected power generation systems can be further divided into battery connected solar power generation systems and grid connected solarpower generation systems without batteries.
A PV power plant with a sets of battery storage system
When a PV power plant installed a battery storage system, at this situation, When the public power grid loses power, the batteries provide emergency power to keep the solar power generation system running and serve as a backup power source, such as a small grid connected power generation system installed in residential buildings.
Grid connected solar power generation system without battery
Grid-connected solar power generation systems without batteries lack relative flexibility on the power supply side and are constrained by public grid systems and transmission channels. They are generally installed on large photovoltaic systems.
Moreover, family grid connected solar power stations supported by national policies can be connected to the grid for free, and excess electricity can also be sold to power companies.
The disadvantage of grid connected solar power generation systems is that when the public power grid loses power, solar power generation cannot operate, and cannot cope with unexpected situations, resulting in insufficient flexibility in power dispatch.
The grid connected solar power generation system can be applied to large-scale solar power stations established in large deserts, wastelands, and other areas, as well as to distributed solar power stations for individual users and households’ spontaneous self use and surplus electricity connected to the grid.
Independent solar power generation system
Independent solar power generation system refers to a solar power generation system that operates independently of the power grid, also known as off grid solar power generation, mainly composed of solar cell components, controllers, inverters, and batteries.
Independent solar power generation systems are generally distributed in scattered and remote areas without power grids. Common solar power generation systems with batteries, such as village power supply systems in remote areas, solar household power supply systems, and solar street lights, can operate independently.
The advantage of an independent solar power generation system is that it can achieve energy storage. Cyclic charging and discharging can operate stably even without power supply from the grid, and is not limited by geographical limitations. It can be widely used, and has strong practicality for areas with power shortages and frequent power outages.
The disadvantage of independent solar power generation systems is that their construction and usage costs are too high, with expensive batteries that require regular maintenance and replacement, and insufficient economic efficiency.
The application of independent solar power generation systems can be divided into two categories: DC solar power generation and AC solar power generation, such as solar water pumps and solar power generation systems with complementary power supply.
According to whether the solar power system is centralized in grid connection, it can also be divided into centralized grid connected solar power systems and distributed grid connected solar power systems.
Centralized solar power generation system
Centralized solar power refers to the installation of photovoltaic arrays in large solar power plants and water solar power plants located in wide and abundant areas such as deserts, mines, and water surfaces. Power generation is directly connected to the public power grid and high-voltage transmission system, achieving long-distance transmission, such as large national level solar power plants.
Centralized solar power system has advantages such as flexible location and operation, higher stability of power generation output, and strong environmental adaptability. However, its disadvantage is that it relies on long-distance transmission lines to transmit electricity to the grid, which can easily cause voltage instability and high investment costs.
Distributed solar power generation system
Distributed solar power system is a power generation facility built near the user’s site and requires balanced regulation of the distribution system.
Distributed solar power systems have the advantages of being able to provide nearby power supply, save land, have low difficulty in grid connection, operate flexibly, and have low initial investment costs. However, their disadvantages are that voltage and reactive power regulation are difficult, and they rely on energy management systems at the distribution network level for regulation. The distribution network also suffers from adverse current losses.
Advantages of solar power
Low carbon environmental protection: It will not produce a large amount of greenhouse gases and pollute the environment like fossil fuels.
Natural renewability: solar power generation utilizes solar energy, which is inexhaustible.
Long service life: solar power modules such as polycrystalline silicon can be used for more than 20 years.
Low maintenance cost: After the completion of the solar power generation system, the maintenance cost is lower than that of conventional power plants.
No noise pollution: The solar power system operates without mechanical rotating components and is quiet without generating noise.
Modular design: The solar power system can adjust its capacity according to needs, making installation flexible and convenient.
Safety: The solar power system does not consume fuel and has high safety performance.
High altitude: In areas with sufficient sunlight and high altitude, solar power generation is positively correlated with light intensity.
Independent power supply: It can operate off the grid, provide independent power supply, and is not affected by the public power grid.
Stable operation: It can achieve normal power supply in harsh weather conditions.
Disadvantages of photovoltaic power generation
High initial investment cost: The early investment cost of solar power systems is relatively high, and it is necessary to evaluate the economy of individual solar power systems and install them reasonably.
Volatility: solar power generation has significant fluctuations, especially in remote areas where the power grid may not be able to absorb it, requiring the use of energy storage equipment.
Intermittent: solar power generation is affected by climate factors such as season and light, resulting in unstable power generation.
Professional training required: The photovoltaic system uses new technologies that users are not familiar with, and specialized technical training is required for relevant personnel before the operation of the solar power system.
Main applications of solar power
With the widespread application of solar power generation in the fields of construction, industry, and agriculture, multiple application systems related to photovoltaic manufacturing have also emerged.
Energy sector
The application of photovoltaic technology in the global power supply field is quite extensive. Photovoltaic power generation can provide green electricity and is an important component of renewable energy generation. Common applications in the solar green power industry include solar power plants, grid connected solar power generation systems, independent solar power generation systems, etc.
The global solar power generation industry is in a period of rapid development. Europe and America are developing photovoltaic green power industries to increase the proportion of clean energy power generation, reduce dependence on fossil energy power generation, and achieve sustainable development of electricity supply. China is building photovoltaic industry bases in the central and western regions to solve the problem of electricity shortage in Tibet and Xinjiang, and utilizing the surplus green electricity generated by photovoltaic power generation through the West East Power Transmission Project, Deliver to eastern cities to create solar green electricity revenue for the western region.
Construction field
In the context of carbon reduction in the construction industry, the green electricity brought by solar power system can reduce carbon emissions on the renewable energy side of the construction industry. The industrial application and development model of integrated photovoltaics and buildings is the key to creating low-carbon and green buildings, such as rooftop photovoltaics in industrial parks, to solve the energy supply problem in the park.
Agricultural sector
Photovoltaic agriculture is a new form of agriculture and a key to promoting the sustainable development of animal husbandry, fisheries, and planting. The integration of photovoltaic and agriculture not only increases farmers’ income, but also improves the efficiency of land resource utilization, achieving green and low-carbon development in rural areas.
For example, in the western region, photovoltaics can be installed on the desert Gobi to transmit green electricity. After the light in the desert Gobi is converted into electricity by photovoltaics, it can promote the ecological restoration of the desert Gobi, regenerate green plants, and turn into grasslands. In contrast, herdsmen in the western region can graze in photovoltaic bases to promote sustainable development of animal husbandry, forming an ecological agricultural development model of photovoltaic power generation, cattle and sheep animal husbandry, and grassland ecological carbon sink.
Automotive sector
The global automotive industry is shifting towards electrification and intelligent development, and the electric drive mode of new energy vehicles can achieve carbon reduction in the transportation sector and reduce carbon emissions during the use of automobiles.
The industrial application model of photovoltaic and new energy vehicles solves the problem of green charging for new energy vehicles. The use of green electricity provided by photovoltaic power stations and photovoltaic charging infrastructure will achieve carbon neutrality on the energy supply side, further reduce carbon emissions, and enable the new energy vehicle industry to achieve long-term low-carbon sustainable development mode
Hydrogen energy field
Green hydrogen is a clean and efficient energy source that promotes energy carbon neutrality. In the process of producing green hydrogen, if fossil fuels are burned to produce hydrogen, it will bring a large amount of carbon emissions. In green hydrogen production models such as electrolytic water hydrogen production, the use of photovoltaic green electricity will reduce the carbon emissions on the energy side of the green hydrogen manufacturing process. Photovoltaic hydrogen production is the main direction for global economic development of the green hydrogen industry.
Practical applications of solar power
In 2013, EU countries added nearly 11GW of photovoltaic installed capacity, the United States added 5.1GW, and China added 11.8GW, becoming the world’s largest photovoltaic market. This is also the first time since 2003 that the EU has lost its global leading position in terms of new installed capacity indicators for solar power generation. However, the cumulative total photovoltaic installed capacity of the European Union reached 81.5GW, still accounting for 59% of the global market share, higher than the market share of China and the United States.
In 2015, China’s cumulative installed capacity of photovoltaic power generation reached 43.18 million kilowatts, surpassing the European Union and the United States, officially becoming the country with the largest installed capacity of photovoltaic power generation in the world. The annual power generation exceeded 39.2 billion kilowatt hours. At the end of 2016, the cumulative installed capacity of solar photovoltaic power generation in the world exceeded 300 GW, with 24 countries passing the GW barrier, and 6 countries having a cumulative installed capacity exceeding 10 GW.
In 2022, the cumulative installed capacity of global photovoltaics exceeded 1000GW, officially entering the terawatt era, and China in Asia is the main contributor to the new installed capacity of global photovoltaics.
According to the Renewable Energy Power Generation Cost Report from 2010 to 2019, the global cost of photovoltaic power generation per kilowatt hour has decreased from $0.378 per kilowatt hour to $0.068 per kilowatt hour, a decrease of 82%.
The global solar power generation has steadily increased, with China’s solar power generation reaching 174GW in 2018, ranking first in the world; The United States has achieved 63GW of photovoltaic power generation, ranking second in the world; Japan has achieved 60GW of photovoltaic power generation, ranking third in the world; Germany’s photovoltaic power generation reached 46GW, ranking fourth in the world. In 2023, the installed capacity of China’s photovoltaic industry ranked first globally for 10 consecutive years, and the newly added total installed capacity ranked first globally for 8 consecutive years.
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