[responsivevoice_button rate=”1″ pitch=”1.2″ volume=”0.8″ voice=”Vietnamese Male” buttontext=”Play”]
So what is Solar Energy - Solar Power - Solar energy technology?
Solar energy, the radiation of light and heat from the Sun, has been harnessed by humans since ancient times using a range of ever-evolving technologies. Solar radiation, along with secondary resources of solar energy such as wind and wave power, water power and biomass, make up most of the renewable energy available on Earth. Only a very small portion of available solar energy is used.
Solar power means electricity generation based on heat engines and photovoltaic cells. The use of solar energy is limited only by human ingenuity. Partial list of solar applications space heating and cooling through solar architecture, through drinking water distillation and disinfection, daylight lighting, solar hot water , solar cooking, and high temperature thermal processes for industrial purposes. To collect solar energy, the most common way is to use solar panels.
Solar technologies are widely described as either passive solar or active solar depending on how they capture, convert and distribute solar energy. Active solar techniques include the use of photovoltaic panels and endothermic solar energy to harvest energy. Passive solar techniques include orienting a building toward the Sun, selecting materials with favorable thermal mass or light dispersion properties, and designing spaces for natural air circulation. .
See more: How to distinguish between rooftop and ground-connected solar power systems
General knowledge about energy from the sun
The Earth receives 174 petawatts (PW) of incoming solar radiation (insolation) in the upper atmosphere. About 30% is reflected back into space while the rest is absorbed by clouds, oceans and land. The spectrum of solar light at the Earth's surface is mainly spread across the visible and near-infrared ranges with a small role in the near-ultraviolet
The Earth's surface, seas and atmosphere absorb solar radiation, and this increases their temperature. Warm air containing evaporated water from the oceans rises, causing atmospheric circulation or convection. When the air reaches a high altitude where the temperature is low, water vapor condenses into clouds, which rain onto the Earth's surface, completing the water cycle. The latent heat of water condensation amplifies convection, producing atmospheric phenomena such as winds, hurricanes and hurricanes. Sunlight absorbed by the oceans and lands keeps the surface at an average temperature of 14°C. By photosynthesis plants convert solar energy into chemical energy, which produces food, wood and biomass from fossil-based fuels.
The total amount of solar energy absorbed by the Earth's atmosphere, oceans and landmass is approximately 3.850.000 exajoules (EJ) per year <- – SMIL quotes a solar absorption flux of 122 PW. Multiply this number by the number of seconds in a year that produces 3.850.000 EJ. -> In 2002, this was the energy in one hour compared to the world used in one year.
Chargeable solar lights during the day and lighting at dusk are a common sight along the walkway
Although daylight saving is promoted as a way to use sunlight to save energy, recent research has been limited and reports conflicting results: some studies report reports savings, but just as many show ineffectiveness or even losses, especially when gasoline consumption is taken into account. Electricity use is greatly influenced by climate, geography and economics, making it difficult to generalize from single studies.
Solar thermal technology and its applications
Solar thermal technology can be used for water heating, space heating, space cooling and process heat generation.
Applying solar thermal technology to heat water
Solar hot water systems use sunlight to heat water. In low geographical latitudes (below 40 degrees) 60-70% of hot water usage with temperatures up to 60 °C can be provided by solar heating systems. The most common types of solar water heaters are evacuated tube collectors (44%) and flat glass plate collectors (34%) which are commonly used for domestic hot water; and uncoated collectors (21%) used mainly to heat swimming pools.
By 2007, the total installed capacity of solar hot water systems was approximately 154 GW. China leads the world in their deployment with 70 GW already installed. 2006 and the long-term target of 210 GW by 2020. Israel and Cyprus are the per capita leaders in the use of solar hot water systems with more than 90% of households using them at United States, Canada and Australia swimming pool heating is the dominant application of solar hot water with an installed capacity of 18 GW in 2005
Applying solar thermal technology in heating, cooling and ventilation systems
In the United States, heating, ventilation, and air conditioning (HVAC) systems account for 30% (4,65 EJ) of energy used in commercial buildings and nearly 50% (10,1 EJ) of energy used in commercial buildings. amount used in residential buildings. Solar heating, cooling and ventilation technology can be used to offset some of this energy.
Thermal mass is any material that can be used to store hot heat from the Sun in the case of solar energy. Common thermomass materials include stone, cement, and water. They have been used historically in arid climates and warm temperate regions to keep buildings cool by absorbing solar energy during the day and radiating stored heat to cool the air during the day. night. However, they can also be used in cold temperate areas to maintain warmth. The size and location of the thermal mass depends on many factors such as climatic conditions, daylight illumination and shade. When properly combined, thermal mass maintains space temperatures within a comfortable range and reduces the need for auxiliary heating and cooling equipment.
A solar chimney (or thermal chimney, in this context) is a passive solar ventilation system consisting of a vertical shaft connecting the interior and exterior of a building. Due to the heating of the chimney, the air inside is heated causing an updraft that pulls the air through the building. Performance can be improved by using glass and thermomass materials in a way that mimics a greenhouse.
Deciduous trees and plants have been developed as a means of controlling solar heating and cooling. When planted on the south side of a building, their leaves provide shade in the summer, while their bare branches allow light to pass in the winter. Since bare trees shade 1/3 to 1/2 of the incoming solar radiation, there is a trade-off between the benefit of summer shade and the corresponding loss of winter heating. In climates with significant heating loads, deciduous trees should not be planted on the south side of a building because they will interfere with the availability of winter solar energy. However, they can be used on the east and west sides to provide a degree of summer shade without affecting winter solar gain.
Applying solar thermal technology in water treatment
Solar distillation can be used to make salty or brackish water potable. The first example of these is by the sixteenth-century Arab alchemist. The first large-scale solar distillation project was built in 1872 in the Chilean mining town of Las Salinas. The plant, which has a 4.700 square meter solar collection area, can produce up to 2L per day and 22.700 years operation. Specific distillation designs include single slope, double slope (or greenhouse), vertical, conical, reverse absorption, multiple wick, and multiple influence. These stills can operate in passive, active, or hybrid mode. Double-slope stills are most economical for decentralized home uses, while multi-slope active units are more suitable for large-scale applications.
Solar water sterilization (SODIS) involves exposing water-filled polyethylene terephthalate (PET) plastic bottles to sunlight for several hours. Exposure times vary depending on weather and climate from a minimum of six hours to two days in total overcast conditions. It is recommended by the World Health Organization as a viable method for Household water management and safe storage. More than two million people in developing countries use this method for their daily drinking water.
Solar energy can be used in a stabilization pond to treat wastewater without chemicals or electricity. An added environmental advantage is that algae grow in such ponds and consume carbon dioxide in photosynthesis, although algae can produce toxic chemicals that make the water unusable.
Applying solar thermal technology in cooking
Solar cookers use sunlight for cooking, drying and sterilization. They can be grouped into three broad categories: box stoves, plate stoves and reflector stoves. The simplest solar cooker is the first box stove built by Horace de Saussure in 1767. The basic box stove consists of an insulated container with a transparent lid. It can be used effectively with partly overcast skies and will typically reach temperatures of 90-150 °C. Plate stoves use a panel that reflects sunlight directly into an insulated container and reaches temperatures comparable to box stoves. Reflector stoves use different focusing geometries (dishes, troughs, Fresnel mirrors) to concentrate light into a cooking container. These stoves reach temperatures of 315 °C and higher but require direct light to function properly and must be repositioned to track the Sun.
The solar bowl is a concentrating technology used in solar cookers at Auroville, Pondicherry, India, where a spherical static reflector concentrates light along a perpendicular line to the interior of the bowl. surface sphere, and a computer control system moves the receiver to intersect this line. Steam is produced in the receiver at a temperature reaching 150 °C and is then used for process heat in the kitchen.
A reflector developed by Wolfgang Scheffler in 1986 is widely used in solar cookers. Scheffler reflectors are flexible parabolic dishes that combine aspects of bottom and energy tower concentrators. Polar tracking is used to monitor the daily course of the sun, and the reflector curvature is adjusted for seasonal changes in the angle of incidence of sunlight. These reflectors can achieve temperatures of 450-650 °C and have a fixed focal point, simplifying cooking. The world's largest Scheffler reflector system at Abu Road, Rajasthan, India is capable of cooking up to 35.000 meals per day. In 2008, more than 2,000 large Scheffler furnaces were built worldwide.
Application of solar thermal technology with process heat
Concentrated solar technology such as parabolic dishes, troughs and Scheffler reflectors can provide process heat for commercial and industrial applications. The first commercial system is the Solar Total Energy Project (STEP) in Shenandoah, Georgia, USA, a field of 114 parabolic dishes providing 50% of the heating, air conditioning and heating requirements. electricity for a clothing factory. This grid-connected cogeneration system provides 400 kW of electricity plus thermal energy in the form of 401 kW steam and 468 kW chilled water, and has a one-hour peak thermal load storage load.
Evaporation ponds are shallow ponds that concentrate dissolved solids through evaporation. The use of evaporation ponds to obtain salt from seawater is one of the oldest applications of solar energy. Modern uses include concentrated brine solutions used in leach mining and the removal of dissolved solids from waste streams.
Clothing lines, clotheshorses, and clothes racks dry clothes through wind evaporation and sunlight without electricity or gas consumption. In some US states laws protect the “right to dry” clothes.
Unglazed exposed exposed (UTC) perforated walls facing the sun are used for preheating ventilation air. UTCs can increase incoming air temperature up to 22°C and provide outlet temperatures of 45-60°C. Highway collectors' short payback period (3 to 12 years) makes them a more cost-effective alternative to glass collection systems. By 2003, more than 80 systems combined with one district 35.000 m2 collectors have been installed worldwide, including 860 m2 collectors in Costa Rica used to dry coffee beans and 1.300 m2 collectors in Coimbatore, India used to dry marigolds.
Equipment for building solar power systems
Solar power is the conversion of sunlight into electricity, either directly using photovoltaics (PV), or indirectly using concentrated solar power (CSP). CSP systems use lenses, mirrors and tracking systems to focus a large area of sunlight into a small beam. PV converts light into electricity using the photovoltaic effect.
Commercial CSP plants were first developed in the 1980s, and the 354 MW SEGS CSP installation is the largest solar power plant in the world and is located in California's Mojave Desert. Other large CSP plants include Solnova Solar Power Plant (150 MW) and Andasol Solar Power Plant (100 MW), both in Spain. No. 97 MW Sarnia Canada Photovoltaic Power Plant is the world's largest photovoltaic power plant.
-
Concentrated solar power:
Concentrating solar power (CSP) systems use lenses, mirrors and tracking systems to focus a large area of sunlight into a small beam. The concentrated heat is then used as an energy source for a conventional power plant. A variety of concentrator technologies exist, the most developed being Fresnel linear reflector parabolic troughs, Stirling dishes and solar PV towers. Different techniques are used to track the Sun and focus light. In all of these systems a working fluid is heated by concentrated sunlight, and is then used to generate electricity or store energy.
-
Photovoltaic battery:
Solar cells, or photovoltaic (PV) cells, are a device that converts light into electricity using the photovoltaic effect. The first solar cells were built by Charles Fritts in the 1880s. In 1931, a German engineer, Dr. Bruno Lange, developed a photo cell using silver selenide in the of copper oxide. Although the prototype selenium cell converted less than 1% of incident light into electricity, both Ernst Werner von Siemens and James Clerk Maxwell recognized the importance of this discovery. Following the work of Russell Ohl in the 1940s, researchers Gerald Pearson, Calvin Fuller and Daryl Chapin created silicon solar cells in 1954. Early solar cells cost $286 each. watts and achieves 4,5-6% efficiency.
Solar chemistry
Solar chemical processes use solar energy to drive chemical reactions. These processes offset energy that would otherwise have to come from fossil fuel sources and can also convert solar energy into fuel that satisfies storage and transportation conditions. Solar energy causes chemical reactions that can be divided into thermochemical or photochemical A variety of fuels can be produced by artificial photosynthesis Polyelectronic chemical catalysis is involved in making these fuels. Carbon sources (such as methanol) from reducing carbon dioxide is a challenge; a viable alternative is hydrogen produced from protons, although using water as the source of electrons (such as plants ) requires mastering the multielectronic oxidation of two molecular oxygen water molecules. Some are expected to work solar fuel plants in coastal urban areas by 2050 – splitting seawater to provide hydrogen to be run through nearby fuel cell power plants and the purified water produced will go directly into the municipal water system.
Hydrogen production technology has been an important area of solar chemistry research since the 1970s. In addition to electrolysis driven by photovoltaic or thermochemical cells, thermochemical processes have also been explored. break. One such way uses concentrators to split water into oxygen and hydrogen at high temperatures (2300-2.600 °C). Another approach uses heat from solar concentrators to drive renewable natural gas vapor thereby increasing total hydrogen production compared to conventional renewable methods. Thermochemical cycling characterized by decomposition and regeneration of reactants presents another route for hydrogen production. The Solzinc process developed at the Weizmann Institute of Science uses a 1 MW solar furnace to decompose zinc oxide (ZnO) at temperatures above 1200 °C. This reaction initially produces pure zinc, which can then react with water to produce hydrogen
Sandia's Sunshine to Petrol (S2P) technology uses high temperatures created by concentrating sunlight along with a zirconia/ferrite catalyst to break down atmospheric carbon dioxide into oxygen and carbon monoxide (CO). . Carbon monoxide can then be used to synthesize conventional fuels such as methanol, gasoline and jet fuel.
A photoelectrochemical device is a type of battery in which cell solutions (or equivalents) produce energy-rich intermediate chemical products when illuminated. Potentially energy-rich chemical intermediates can be stored and then react at the electrode to generate an electric potential. The ferric-thionine chemical cell is an example of this technology.
Electrochemical cells or PECs consist of a semiconductor, usually titanium dioxide or related titanates, immersed in an electrolyte. When the semiconductor is illuminated an electric potential is developed. There are two types of electrochemical cells: photovoltaic cells that convert light into electricity and photocells that use light to drive chemical reactions such as electrolysis reactions
A combined thermal/photochemical cell has also been proposed. The Stanford PETE process uses solar thermal energy to raise the temperature of a thermometal to about 800C to speed up the production of electricity to electrolyze atmospheric CO2 into carbon or carbon monoxide which can then be used. used to produce fuel, and residual heat can also be used.
Solar car
Development of a solar car has been an engineering goal since the 1980s. The World Solar Challenge is a biannual solar car race where teams from Universities and businesses compete on a 3.021 kilometer (1.877 mi) route through central Australia from Darwin to Adelaide. In 1987, when it was founded, the winner's average speed was 67 kilometers per hour (42 mph) by 2007 the winner's average speed had improved to 90,87 kilometers per hour (56,46 mph). .XNUMX mph)[Conversion: Invalid number] The North American Solar Challenge and the South African Solar Challenge are competitive competitions that reflect international interest in solar vehicle engineering and development
Some cars use solar panels for auxiliary power, such as for air conditioning, to keep the interior cool, thereby reducing fuel consumption.
In 1975, the first practical solar boat was built in the UK. In 1995, passenger boats incorporating PV panels began to appear and be widely used. In 1996, Kenichi Horie made the first solar crossing of the Pacific Ocean, and the raft “sun21” made the first solar crossing of the Atlantic Ocean during the winter of 2006-2007.Yes Plans to go around the world in 2010
Helios UAV in flight using solar energy
In 1974, the AstroFlight Sunrise drone made the first solar powered flight. On April 29, 1979, Solar Riser made the first flight of a solar-powered, fully controlled, human-carrying aircraft, reaching an altitude of 40 feet (12 m). rules]. In 1980, the Gossamer Penguin made its first test flights using only photovoltaic cells. This was quickly followed by the Solar Challenger crossing the English Channel in July 7. In 1981 Eric Scott Raymond in 1990 hops flew from California to North Carolina using solar power. Development then returned to the unmanned aerial vehicle (UAV) Pathfinder (21) and subsequent designs, culminating in the Helios which set the altitude record for a non-propelled aircraft by name. fire at 1997 meters (29.524 ft) in 96.864 The Zephyr, developed by BAE Systems is the latest in a line of record-breaking solar aircraft, flying 2001 hours in 54, a flight lasting months envisioned in 2007.
A solar balloon is a black balloon filled with regular air. When sunlight shines on the balloon, the air inside is heated and expands, causing buoyancy, just like an artificially heated hot air balloon. Some solar balloons are large enough for human flight, but use is often limited to the toy market due to their relatively high surface area to payload ratio.
Solar sails are a proposed form of spacecraft propulsion that uses large membrane mirrors to exploit radiation pressure from the sun. Unlike rockets, solar sails do not require fuel. Although the thrust is small compared to a rocket, it continues as long as the sun shines on the deployed sail, and in vacuum significant space speeds can eventually be achieved
A high-altitude airship (HAA) is a lighter-than-air, unmanned, long-duration vehicle that uses helium for lift, and thin-layer solar cells for propulsion. The U.S. Department of Defense's Missile Defense Agency contracted Lockheed Martin to build it to enhance its Ballistic Missile Defense System (BMDS). Airships have several advantages for solar flight: they do not require propulsion to maintain altitude, and the balloon's nacelle exposes a large area to the sun.
Solar energy storage method
Solar energy at night, and energy storage is an important issue because modern energy systems often assume constant availability of energy.
Thermal mass systems can store solar energy as heat at useful domestic temperatures for each day or season. Thermal storage systems typically use readily available materials with high specific thermal capacities such as soil, water and rock. A well-designed system can lower peak demand, shift usage times to off-peak hours, and reduce overall heating and cooling requirements.
Phase change materials such as paraffin wax and Glauber's Salts are another heat storage medium. These materials are inexpensive, readily available, and can provide useful indoor temperatures (about 64 °C). The “Dover House” (in Dover, Massachusetts) was the first house to use a Glauber salt heating system, in 1948.
Solar energy can be stored at high temperatures using molten salt. Salts are an effective storage medium because they are low cost, have a high specific heat capacity, and can provide heat at temperatures compatible with conventional electrical systems. Solar Two uses this energy storage method, allowing it to store 1,44 TJ in its 68 m3 tank with an annual storage efficiency of around 99%.
Off-grid PV systems have traditionally used rechargeable batteries to store excess electricity. With grid-connected systems, excess electricity can be sent to the transmission grid, while standard grid electricity can be used to meet the shortfall. Net Metering programs give households a credit for any electricity they supply to the grid. This is usually handled legally by “rolling back” the electric meter whenever the house is producing more electricity than it is consuming. If grid electricity usage is below zero, the utility company is required to pay for the extra at the same rate they charge consumers. Another regulatory approach involves the use of two electricity meters, to count electricity consumed versus electricity produced. This is less common due to the increased installation cost of a second meter.
Pumped storage hydropower stores energy in the form of pumped water when energy is available from a low elevation reservoir to a higher elevation. Energy is recovered when demand is high by releasing water to run through a hydroelectric generator
Development, deployment and economics of solar energy
Beginning with the increased use of coal that accompanied the Industrial Revolution, energy consumption has gradually shifted from wood and biomass to fossil fuels. The early development of solar technologies beginning in the 1860s was driven by an expectation that coal would soon become scarce. However, development of solar energy technologies stagnated in the early twentieth century in the face of the increasing availability, economics, and utility of coal and petroleum.
The 1973 oil embargo and the 1979 energy crisis caused a worldwide realignment of energy policy and brought renewed attention to the development of solar energy technology. Deployment strategies focus on incentive programs, such as the Federal Photovoltaic Utilization Program in the US and the Sunshine Program in Japan. Other efforts include the formation of research facilities in the US (SERI, NREL), Japan (NEDO), and Germany (Fraunhofer Institute for Solar Energy Systems ISE).
Commercial solar water heaters began appearing in the United States in the 1890s. These systems increased in use until the 1920s but were gradually replaced by cheaper heating fuels. and more reliable. As with photovoltaics, solar water heating attracted increased attention as a result of the oil crisis in the 1970s but interest dropped in the 1980s due to falling gasoline prices. Developments in the solar water heating sector progressed steadily throughout the 1990s and the growth rate has averaged 20% per year since 1999. Although often underestimated, water heating and cooling Solar power is by far the most widely deployed solar technology with an estimated capacity of 154 GW in 2007.
Nowadays, with progress in manufacturing photovoltaic modules, good quality solar panels (solar leds) have been produced in large quantities, with high performance, serving a variety of daily needs. of humans, these solar panels are diverse in performance (12-24v) and capacity. The trend of using solar energy is increasingly evident and will be the trend of the new era.
Solar power applications in Vietnam
In Vietnam, according to EVN, as of May 30, 5, there were 2019 solar power projects with a total installed capacity of 47 MW connected to the national grid.
In 2019, there are currently 8 solar battery factories being built in Vietnam.
ISO standards related to solar energy equipment
The International Standards Organization has established a number of standards related to solar energy equipment. For example, ISO 9050 relates to building glass while ISO 10217 relates to materials used in solar water heaters.