1 Overview of solar lighting
Solar energy is “inexhaustible”, and pollution-free renewable energy, radiant energy, the Earth’s surface every day to approximately 2.5 millions of barrels of oil. A long period of time, solar energy from the people around were in vain, “slip” of the.With the rapid development of science and technology, development and utilization of solar energy gradually, and has become the most promising environmentally friendly energy sources.
At present, solar energy, there are two main ways.
(1) through the solar cells convert solar energy into electrical energy for power generation, namely photovoltaic power generation, such as solar lighting, solar power stations and so on.
(2) through the collector to make use of solar energy converted to heat energy, such as solar water heaters, solar cookers and so on.
Among them, solar lighting is the use of solar energy is one of the most important way is our main concern and the object of study.
Outdoor lighting, solar lighting, strong development momentum.Solar street lights (non-trunk), solar garden lights, solar lawn lamp, solar traffic lights, solar lights, advertising is no longer uncommon, have become the highlight of the green lighting. We are talking about solar lights, both a lamp, light source, including solar cells, batteries, controller, inverter, poles and other supporting devices.
Solar lighting is the most significant features of energy saving, economical, environmentally friendly, without the traditional public power system for electricity, save power distribution equipment, cables, switches and other investments, basically no running costs.Solar energy into electricity, avoiding the coal, oil, nuclear, etc.
Power generation due to atmospheric and environmental pollution.Conditions in today’s technology, solar powered lighting, especially suitable for long distance or local power supply is not easy.
2 Principles of solar lighting
Solar panels to solar energy into electricity, through power diodes and control system to charge the battery. Charged to a certain extent, self-protection system action inside the controller to cut off the charging power supply. Night, the solar panel as the photoelectric controller, start the controller
, Battery to power lights, lighted lights; morning, solar panels but also acts as a photoelectric controller, start the controller
, Cut off the light power to begin again the work of converting solar energy into electricity. Solar lights brighten, they also can be dimmed according to the setting.
3, composed of solar lighting
Solar lighting powered by solar panels, batteries, solar lights for the controller, and light poles and other components. Highlighted below, solar cells, batteries, inverters (AC light bulbs use), solar lights for the controller, light and so on.
3.1 Solar Cells
3.1.1 Principles of solar cell
Is the use of photovoltaic solar cells convert the sun’s radiation theory of light into electrical energy by the semiconductor material of the device, this energy conversion process is usually called the “photovoltaic effect”, also known as solar cells, “photovoltaic cells.”
When the sun light shines from the P, N-type conductivity of two different types of homogenous composition of semiconductor materials when the P-N junction, under certain conditions, solar radiation absorbed by the semiconductor material to form a built-in electrostatic field. If the electrostatic field from the built-in electrodes and connected to the appropriate leads on both sides of the load, it will form a voltage and current, which is the basic principle of solar cells.
Single solar cell is a thin slice of semiconductor P-N junction.Standard light conditions, the rated output voltage is 0.48V. In order to obtain higher output voltage and larger capacity
You tend to film solar cells connected together and more.
Power output of solar cells is random. Different times, different locations, different installation methods, the same piece of solar cell output power is also different.
Currently, the photoelectric conversion rate of solar cells more than ten per cent or more generally
Individual solar cells developed countries can reach the photoelectric conversion rate has been about 30%.
3.1.2 Classification of solar cells
(1) silicon solar cells;
(2) inorganic salts such as: III-V compounds, gallium arsenide, cadmium sulfide, copper, indium, selenium and other materials in the battery multiple compounds;
(3) Preparation of functional polymer materials for solar cells;
(4) nano-crystalline solar cells.
Silicon solar cell technology is relatively mature, the band gap semiconductor material is not too wide, photoelectric conversion rate higher, the material itself does not cause pollution, so the silicon solar cell is the best material. Other materials-based solar cells are also being developed and the development process.
3.1.3 silicon solar cells
(1) single crystal silicon cells: Currently, silicon solar cells conversion rate was the highest (20%), most mature technology, but the high price of silicon materials, manufacturing process complicated
, Resulting in high prices of silicon cost, the development of silicon solar cells become a major obstacle, is now gradually being polycrystalline silicon thin film solar cells and amorphous silicon thin film solar cells instead.
Currently, silicon solar cells in road lighting, traffic signals and other outdoor lighting in more general use, photoelectric conversion rate of 11% to 24% longer service life.
(2) polycrystalline silicon cells: the use of polycrystalline silicon thin-film batteries since much less silicon than silicon, the efficiency of recession and other issues does not exist, and may low-cost substrate materials in the preparation. Polycrystalline silicon thin film solar cells far less than the cost of silicon cells, photovoltaic conversion rate of nearly 20%, higher than amorphous silicon thin film batteries. Therefore, the polycrystalline silicon thin film solar cells is expected to become the dominant product.
Polycrystalline silicon solar cells for outdoor lighting applications will be more extensive.
(3) amorphous silicon cell: amorphous silicon thin film solar cell production is simple, low cost, ease of mass production, widespread attention has been paid and the rapid development of photoelectric conversion rate of more than 14.5%
, But less stable. Improve the conversion rate and stability of amorphous silicon thin film solar cell development. At present, the amorphous silicon in low-power battery power system used more often.
3.1.4 Other research and development of solar cells
(1) nano-crystalline chemical solar cells: nanocrystalline solar cell is a new chemical solar cells
Is still in the process of development,
Nanocrystalline TiO2 solar cells in which much attention.Nanocrystalline TiO2 solar cells more than 10% efficiency, production cost of silicon solar cells 1 / 5 to 1 / 10, life expectancy up to 20 years.
(2) modified electrode polymer multilayer solar cells: materials for the organic material, flexible, and make easy, extensive source material, the cost is low. Performance and life far better than silicon cells, but may provide cheap electricity. The study has just begun.
(3) Multiple compound thin film solar cells: Some metal compounds such as cadmium sulfide, cadmium telluride polycrystalline thin-film battery is more efficient than amorphous silicon thin film solar cell efficiency, lower costs than single crystal silicon cells, and also easy to mass production, However, cadmium is highly toxic and cause serious pollution, therefore, can not develop applications.
3.1.5 Select the capacity of solar cells
Solar power must be 4 times higher than the load power over the system to work properly.
3.2 Battery
3.2.1 The battery must be equipped with solar lighting
The battery must be equipped with solar lighting to work, because:
(1) solar photovoltaic conversion can only work during the day
, Energy can be used for lighting at night
Therefore, the battery must be within the reserve. Reserve capacity must be adequate lighting to local needs several consecutive cloudy days.
(2) The energy output of solar panels extremely unstable, with the battery, the solar lights, load to work properly.
3.2.2 the type of battery
And application
(1) lead-acid batteries: the traditional batteries, low energy density, environmental pollution is more serious, will gradually be eliminated.
(2) Ni-Cd (nickel – cadmium) batteries: lead acid battery performance than the superior, but less than the energy density of cadmium pollution is serious, most countries strictly control the production and use of such batteries.
(3) Ni-H (Ni – MH) batteries: a high energy density, light weight, long life, no environment pollution, there is a positive development.90 developed countries in the 20th century has entered the stage of industrialization.
(4) Lithium batteries: new high-energy chemical power, high-capacity, high power, small size, non-polluting characteristics.Lithium batteries used in notebook computers and mobile phones.
At present, extensive use of fully enclosed outdoor lighting, maintenance-free lead-acid batteries. Small lighting, a large number of laptops and mobile phones use lithium batteries, nickel metal hydride batteries. Applications lithium batteries is gradually expanding.
Development, promotion is the development of pollution-free solar lighting batteries urgent need to address a major issue.
3.2.3 Battery capacity choice
China’s vast territory, large differences in climate, energy stored in batteries during the day and night lighting should be able to meet the demand, and should continuously rainy weather to meet local demand for lighting at night. However, do not have the selected battery capacity is too large, otherwise, often in a loss of battery power status, will affect battery life, resulting in unnecessary waste.
Select the size of the battery capacity, higher than in western China proposed lighting at more than 4 times the power consumption; northern lights proposed at higher power consumption more than 5 times; the south light on power consumption higher than the recommended 6 times .
3.3 Controller
Controller’s role is to control the working status of solar lighting systems, such as lighting control or set of light switches, dimmers, lightning protection, short circuit protection, over charge the battery for protection, anti-charge protection, over discharge protection, temperature compensation and so on.
Solar light controller is the “brain.” With the passing of the controller, solar lights can work smoothly, while extending the life of batteries and other devices.
3.4 Inverter
Inverter is the output of the DC battery into alternating current devices, lighting, do not have to set the DC load, lighting load for the exchange of load must be used. According to China’s current situation, the general battery for the 24V (or 12V, 36V), outdoor lighting bulbs (lamp) is 220V, 50Hz AC, therefore, mostly inverter DC24V (or 12V, 36V) / AC220V voltage form. Inverter should also have short circuit protection, undervoltage protection, overcurrent, reverse polarity protection and lightning protection.
Lighting load of 3.5
Solar photovoltaic lighting Because there is a low conversion rate, cost of higher prices and other factors, making the current scope of its application is limited to traffic lights, landscape lighting, decorative lighting range to lawn, garden lights, low-power road (non-trunk) light mainly. Solar lighting to LED light emitting diode, light-based energy efficient trichromatic
May also use the low-pressure sodium lamp, lamp, individual cases with low-power HID lamps.
Compared with the energy-saving LED lights, the former longer life expectancy, low luminous efficiency; the latter short-lived, light-efficient. In different situations, to go through economic and technical comparison, select the appropriate source.
Solar traffic lights with LED light-emitting diode light source, long life LED lights meet the requirements of performance.
Can regulate lighting, frequent switching function following low-power 1W solar lawn light, LED as the light source should be used generally. For larger solar power lawn, the three primary colors currently in use energy efficient lamps is reasonable.
Garden lights and street lights to decorate the main, the proposals selected LED light-emitting diode; to lighting dominant, recommended to choose the three primary colors Energy efficient or low pressure sodium lamp.
With the LED light emitting diode efficiency improvements, solar lighting source will be supporting the increasing use of LED light-emitting diodes.
4, the development trend of solar lighting
(1) enhance the photoelectric conversion rate of solar panels;
(2) to increase system capacity
To meet the power requirements of outdoor lighting;
(3) reduce costs. Currently, a set of solar lights (set) is the general lighting (set) several times, the promotion of the use of solar lighting;
(4) to extend the life of batteries and other devices, thus extending the life of solar lighting systems;
(5) reduce the solar panels, batteries and other size, landscaping rod;
(6) serious pollution of the phasing out of lead-acid batteries, Ni-Cd batteries, etc.
Accelerate the develop pollution-free batteries, a real sense of environmental protection;
(7) solar lighting, after technological advances and lower prices, will become the leading light of the new century.
Solar energy is “inexhaustible”, and pollution-free renewable energy, radiant energy, the Earth’s surface every day to approximately 2.5 millions of barrels of oil. A long period of time, solar energy from the people around were in vain, “slip” of the.With the rapid development of science and technology, development and utilization of solar energy gradually, and has become the most promising environmentally friendly energy sources.
At present, solar energy, there are two main ways.
(1) through the solar cells convert solar energy into electrical energy for power generation, namely photovoltaic power generation, such as solar lighting, solar power stations and so on.
(2) through the collector to make use of solar energy converted to heat energy, such as solar water heaters, solar cookers and so on.
Among them, solar lighting is the use of solar energy is one of the most important way is our main concern and the object of study.
Outdoor lighting, solar lighting, strong development momentum.Solar street lights (non-trunk), solar garden lights, solar lawn lamp, solar traffic lights, solar lights, advertising is no longer uncommon, have become the highlight of the green lighting. We are talking about solar lights, both a lamp, light source, including solar cells, batteries, controller, inverter, poles and other supporting devices.
Solar lighting is the most significant features of energy saving, economical, environmentally friendly, without the traditional public power system for electricity, save power distribution equipment, cables, switches and other investments, basically no running costs.Solar energy into electricity, avoiding the coal, oil, nuclear, etc.
Power generation due to atmospheric and environmental pollution.Conditions in today’s technology, solar powered lighting, especially suitable for long distance or local power supply is not easy.
2 Principles of solar lighting
Solar panels to solar energy into electricity, through power diodes and control system to charge the battery. Charged to a certain extent, self-protection system action inside the controller to cut off the charging power supply. Night, the solar panel as the photoelectric controller, start the controller
, Battery to power lights, lighted lights; morning, solar panels but also acts as a photoelectric controller, start the controller
, Cut off the light power to begin again the work of converting solar energy into electricity. Solar lights brighten, they also can be dimmed according to the setting.
3, composed of solar lighting
Solar lighting powered by solar panels, batteries, solar lights for the controller, and light poles and other components. Highlighted below, solar cells, batteries, inverters (AC light bulbs use), solar lights for the controller, light and so on.
3.1 Solar Cells
3.1.1 Principles of solar cell
Is the use of photovoltaic solar cells convert the sun’s radiation theory of light into electrical energy by the semiconductor material of the device, this energy conversion process is usually called the “photovoltaic effect”, also known as solar cells, “photovoltaic cells.”
When the sun light shines from the P, N-type conductivity of two different types of homogenous composition of semiconductor materials when the P-N junction, under certain conditions, solar radiation absorbed by the semiconductor material to form a built-in electrostatic field. If the electrostatic field from the built-in electrodes and connected to the appropriate leads on both sides of the load, it will form a voltage and current, which is the basic principle of solar cells.
Single solar cell is a thin slice of semiconductor P-N junction.Standard light conditions, the rated output voltage is 0.48V. In order to obtain higher output voltage and larger capacity
You tend to film solar cells connected together and more.
Power output of solar cells is random. Different times, different locations, different installation methods, the same piece of solar cell output power is also different.
Currently, the photoelectric conversion rate of solar cells more than ten per cent or more generally
Individual solar cells developed countries can reach the photoelectric conversion rate has been about 30%.
3.1.2 Classification of solar cells
(1) silicon solar cells;
(2) inorganic salts such as: III-V compounds, gallium arsenide, cadmium sulfide, copper, indium, selenium and other materials in the battery multiple compounds;
(3) Preparation of functional polymer materials for solar cells;
(4) nano-crystalline solar cells.
Silicon solar cell technology is relatively mature, the band gap semiconductor material is not too wide, photoelectric conversion rate higher, the material itself does not cause pollution, so the silicon solar cell is the best material. Other materials-based solar cells are also being developed and the development process.
3.1.3 silicon solar cells
(1) single crystal silicon cells: Currently, silicon solar cells conversion rate was the highest (20%), most mature technology, but the high price of silicon materials, manufacturing process complicated
, Resulting in high prices of silicon cost, the development of silicon solar cells become a major obstacle, is now gradually being polycrystalline silicon thin film solar cells and amorphous silicon thin film solar cells instead.
Currently, silicon solar cells in road lighting, traffic signals and other outdoor lighting in more general use, photoelectric conversion rate of 11% to 24% longer service life.
(2) polycrystalline silicon cells: the use of polycrystalline silicon thin-film batteries since much less silicon than silicon, the efficiency of recession and other issues does not exist, and may low-cost substrate materials in the preparation. Polycrystalline silicon thin film solar cells far less than the cost of silicon cells, photovoltaic conversion rate of nearly 20%, higher than amorphous silicon thin film batteries. Therefore, the polycrystalline silicon thin film solar cells is expected to become the dominant product.
Polycrystalline silicon solar cells for outdoor lighting applications will be more extensive.
(3) amorphous silicon cell: amorphous silicon thin film solar cell production is simple, low cost, ease of mass production, widespread attention has been paid and the rapid development of photoelectric conversion rate of more than 14.5%
, But less stable. Improve the conversion rate and stability of amorphous silicon thin film solar cell development. At present, the amorphous silicon in low-power battery power system used more often.
3.1.4 Other research and development of solar cells
(1) nano-crystalline chemical solar cells: nanocrystalline solar cell is a new chemical solar cells
Is still in the process of development,
Nanocrystalline TiO2 solar cells in which much attention.Nanocrystalline TiO2 solar cells more than 10% efficiency, production cost of silicon solar cells 1 / 5 to 1 / 10, life expectancy up to 20 years.
(2) modified electrode polymer multilayer solar cells: materials for the organic material, flexible, and make easy, extensive source material, the cost is low. Performance and life far better than silicon cells, but may provide cheap electricity. The study has just begun.
(3) Multiple compound thin film solar cells: Some metal compounds such as cadmium sulfide, cadmium telluride polycrystalline thin-film battery is more efficient than amorphous silicon thin film solar cell efficiency, lower costs than single crystal silicon cells, and also easy to mass production, However, cadmium is highly toxic and cause serious pollution, therefore, can not develop applications.
3.1.5 Select the capacity of solar cells
Solar power must be 4 times higher than the load power over the system to work properly.
3.2 Battery
3.2.1 The battery must be equipped with solar lighting
The battery must be equipped with solar lighting to work, because:
(1) solar photovoltaic conversion can only work during the day
, Energy can be used for lighting at night
Therefore, the battery must be within the reserve. Reserve capacity must be adequate lighting to local needs several consecutive cloudy days.
(2) The energy output of solar panels extremely unstable, with the battery, the solar lights, load to work properly.
3.2.2 the type of battery
And application
(1) lead-acid batteries: the traditional batteries, low energy density, environmental pollution is more serious, will gradually be eliminated.
(2) Ni-Cd (nickel – cadmium) batteries: lead acid battery performance than the superior, but less than the energy density of cadmium pollution is serious, most countries strictly control the production and use of such batteries.
(3) Ni-H (Ni – MH) batteries: a high energy density, light weight, long life, no environment pollution, there is a positive development.90 developed countries in the 20th century has entered the stage of industrialization.
(4) Lithium batteries: new high-energy chemical power, high-capacity, high power, small size, non-polluting characteristics.Lithium batteries used in notebook computers and mobile phones.
At present, extensive use of fully enclosed outdoor lighting, maintenance-free lead-acid batteries. Small lighting, a large number of laptops and mobile phones use lithium batteries, nickel metal hydride batteries. Applications lithium batteries is gradually expanding.
Development, promotion is the development of pollution-free solar lighting batteries urgent need to address a major issue.
3.2.3 Battery capacity choice
China’s vast territory, large differences in climate, energy stored in batteries during the day and night lighting should be able to meet the demand, and should continuously rainy weather to meet local demand for lighting at night. However, do not have the selected battery capacity is too large, otherwise, often in a loss of battery power status, will affect battery life, resulting in unnecessary waste.
Select the size of the battery capacity, higher than in western China proposed lighting at more than 4 times the power consumption; northern lights proposed at higher power consumption more than 5 times; the south light on power consumption higher than the recommended 6 times .
3.3 Controller
Controller’s role is to control the working status of solar lighting systems, such as lighting control or set of light switches, dimmers, lightning protection, short circuit protection, over charge the battery for protection, anti-charge protection, over discharge protection, temperature compensation and so on.
Solar light controller is the “brain.” With the passing of the controller, solar lights can work smoothly, while extending the life of batteries and other devices.
3.4 Inverter
Inverter is the output of the DC battery into alternating current devices, lighting, do not have to set the DC load, lighting load for the exchange of load must be used. According to China’s current situation, the general battery for the 24V (or 12V, 36V), outdoor lighting bulbs (lamp) is 220V, 50Hz AC, therefore, mostly inverter DC24V (or 12V, 36V) / AC220V voltage form. Inverter should also have short circuit protection, undervoltage protection, overcurrent, reverse polarity protection and lightning protection.
Lighting load of 3.5
Solar photovoltaic lighting Because there is a low conversion rate, cost of higher prices and other factors, making the current scope of its application is limited to traffic lights, landscape lighting, decorative lighting range to lawn, garden lights, low-power road (non-trunk) light mainly. Solar lighting to LED light emitting diode, light-based energy efficient trichromatic
May also use the low-pressure sodium lamp, lamp, individual cases with low-power HID lamps.
Compared with the energy-saving LED lights, the former longer life expectancy, low luminous efficiency; the latter short-lived, light-efficient. In different situations, to go through economic and technical comparison, select the appropriate source.
Solar traffic lights with LED light-emitting diode light source, long life LED lights meet the requirements of performance.
Can regulate lighting, frequent switching function following low-power 1W solar lawn light, LED as the light source should be used generally. For larger solar power lawn, the three primary colors currently in use energy efficient lamps is reasonable.
Garden lights and street lights to decorate the main, the proposals selected LED light-emitting diode; to lighting dominant, recommended to choose the three primary colors Energy efficient or low pressure sodium lamp.
With the LED light emitting diode efficiency improvements, solar lighting source will be supporting the increasing use of LED light-emitting diodes.
4, the development trend of solar lighting
(1) enhance the photoelectric conversion rate of solar panels;
(2) to increase system capacity
To meet the power requirements of outdoor lighting;
(3) reduce costs. Currently, a set of solar lights (set) is the general lighting (set) several times, the promotion of the use of solar lighting;
(4) to extend the life of batteries and other devices, thus extending the life of solar lighting systems;
(5) reduce the solar panels, batteries and other size, landscaping rod;
(6) serious pollution of the phasing out of lead-acid batteries, Ni-Cd batteries, etc.
Accelerate the develop pollution-free batteries, a real sense of environmental protection;
(7) solar lighting, after technological advances and lower prices, will become the leading light of the new century.
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