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Here is a compilation of essays on ‘Solar Energy’ for class 6, 7, 8, 9, 10, 11 and 12. Find paragraphs, long and short essays on ‘Solar Energy’ especially written for school and college students.
Essay on Solar Energy
Essay Contents:
- Essay on the Introduction to Solar Energy
- Essay on Energy from the Sun
- Essay on Solar Collector
- Essay on Electricity Generation Methods Using Solar Energy
- Essay on Solar Power in India
- Essay on the Challenges and Constraints of Using Solar Energy
Essay # 1. Introduction to Solar Energy:
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Every day, the sun radiates an enormous amount of energy. This energy comes from within the sun itself. Like most stars, the sun is a big gas ball made mostly of hydrogen and helium. The sun produces energy in a process called nuclear fusion.
The high pressure and temperature in the sun’s core cause hydrogen atoms to split apart. Four hydrogen nuclei combine or fuse, to form one helium atom, producing radiant energy in the process.
The sun radiates more energy in one second than the world has used since time began. Only a small portion of this energy strikes the earth, one part in two billion. Yet this amount of energy is enough to meet the world’s needs, if it could be harnessed.
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About 15 percent of the radiant energy that reaches the earth is reflected back into space. Another 30 percent is used to evaporate water, which is lifted into the atmosphere and produces rainfall. The radiant energy is also absorbed by plants, landmasses and the oceans.
Oceans cover more than 70 percent of the earth’s surface and most of the ocean’s energy comes from the sun. Only the tides—caused by the gravitational energy of the moon—and the geothermal energy under the oceans are not solar powered. Ocean currents, waves and winds all are a result of the sun’s radiant energy. Solar energy can also be used to produce electricity with photovoltaic.
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Solar energy, radiant 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 solar-powered resources such as wind and wave-power, hydroelectricity and biomass, account for most of the available renewable energy on earth. Only a minuscule fraction of the available solar energy is used.
Solar powered electrical generation relies on heat engines and photovoltaic. Solar energy’s uses are limited only by human ingenuity. A partial list of solar applications includes space heating and cooling through solar architecture, potable water via, distillation and disinfection, day lighting, solar hot water, solar cooking and high temperature process heat for industrial purposes. To harvest the solar energy, the most common way is to use solar panels.
Solar technologies are broadly characterized as either passive solar or active solar depending on the way they capture, convert and distribute solar energy. Active solar techniques include the use of photovoltaic panels and solar thermal collectors to harness the energy. Passive solar techniques include orienting a building to the sun, selecting materials with favourable thermal mass or light dispersing properties and designing spaces that naturally circulate air.
Solar energy refers primarily to the use of solar radiation for practical ends. However, all renewable energies, other than geothermal and tidal, derive their energy from the sun.
Solar technologies are broadly characterized as either passive or active depending on the way they capture, convert and distribute sunlight. Active solar techniques use photovoltaic panels, pumps and fans to convert sunlight into useful outputs.
Passive solar techniques include selecting materials with favourable thermal properties, designing spaces that naturally circulate air and referencing the position of a building to the Sun. Active solar technologies increase the supply of energy and are considered supply side technologies, while passive solar technologies reduce the need for alternate resources and are generally considered demand side technologies.
Essay # 2. Energy from the Sun:
The Earth receives 174 petawatts (PW) of incoming solar radiation at the upper atmosphere. Approximately 30% is reflected back to space while the rest is absorbed by clouds, oceans and land masses. The spectrum of solar light at the Earth’s surface is mostly spread across the visible and near-infrared ranges with a small part in the near-ultraviolet.
Earth’s land surface, oceans and atmosphere absorb solar radiation and this raises 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.
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The latent heat of water condensation amplifies convection, producing atmospheric phenomena such as wind, cyclones and anti-cyclones. Sunlight absorbed by the oceans and land masses keeps the surface at an average temperature of 14°C. By photosynthesis green plants convert solar energy into chemical energy, which produces food, wood and the biomass from which fossil fuels are derived.
The total solar energy absorbed by Earth’s atmosphere, oceans and land masses is approximately 38,50,000 exajoules (EJ) per year. In 2002, this was more energy in one hour than the world used in one year. Photosynthesis captures approximately 3,000 EJ per year in biomass.
The amount of solar energy reaching the surface of the planet is so vast that in one year it is about twice as much as will ever be obtained from all of the Earth’s non-renewable resources of coal, oil, natural gas and mined uranium combined.
From the table of resources it would appear that solar, wind or biomass would be sufficient to supply all of our energy needs, however, the increased use of biomass has had a negative effect on global warming and dramatically increased food prices by diverting forests and crops into biofuel production. As intermittent resources, solar and wind raise other issues.
Solar energy can be harnessed in different levels around the world. Depending on a geographical location the closer to the equator the more ‘potential’ solar energy is available.
Essay # 3. Solar Collector:
A solar collector is a solar collector designed to collect heat by absorbing sunlight. The term is applied to solar hot water panels, but may also be used to denote more complex installations such as solar parabolic, solar trough and solar towers or simpler installations such as solar air heat.
The more complex collectors are generally used in solar power plants where solar heat is used to generate electricity by heating water to produce steam which drives a turbine connected to an electrical generator. The simpler collectors are typically used for supplemental space heating in residential and commercial buildings. A collector is a device for converting the energy in solar radiation into a more usable or storable form.
The energy in sunlight is in the form of electromagnetic radiation from the infrared (long) to the ultraviolet (short) wavelengths. The solar energy striking the Earth’s surface depends on weather conditions, as well as location and orientation of the surface, but overall, it averages about 1,000 watts per square meter under clear skies with the surface directly perpendicular to the sun’s rays.
Types of Solar Collectors for Heat:
Solar collectors fall into two general categories: non-concentrating and concentrating. In the non-concentrating type, the collector area (i.e., the area that intercepts the solar radiation) is the same as the absorber area (i.e., the area absorbing the radiation). In these types the whole solar panel absorbs the light.
Flat plate and evacuated tube solar collectors are used to collect heat for space heating or domestic hot water.
1. Flat Plate Collectors:
Flat plate collectors, developed by Hottel and Whillier in the 1950s, are the most common type.
They Consist of:
i. A dark flat-plate absorber of solar energy,
ii. A transparent cover that allows solar energy to pass through but reduces heat losses,
iii. A heat-transport fluid (air, antifreeze or water) to remove heat from the absorber, and
iv. A heat insulating backing.
The absorber consists of a thin absorber sheet (of thermally stable polymers, aluminium, steel or copper, to which a matt black or selective coating is applied) often backed by a grid or coil of fluid tubing placed in an insulated casing with a glass or polycarbonate cover. In water heat panels, fluid is usually circulated through tubing to transfer heat from the absorber to an insulated water tank.
This may be achieved directly or through a heat exchanger. Most air heat fabricates and some water heat manufacturers have a completely flooded absorber consisting of two sheets of metal which the fluid passes between. Because the heat exchange area is greater they may be marginally more efficient than traditional absorbers.
There are a number of absorber piping configurations:
i. Harp traditional design with bottom pipe risers and top collection pipe, used in low pressure thermosyphon and pumped systems.
ii. Serpentine one continuous S that maximizes temperature but not total energy yield in variable flow systems used in compact solar domestic hot water only systems (no space heating role).
iii. Completely flooded absorber consisting of two sheets of metal stamped to produce a circulation zone. Because the heat exchange area is greater they may be marginally more efficient than traditional absorbers.
As an alternative to metal collectors, new polymer flat plate collectors are now being produced in Europe. These may be wholly polymer, or they may include metal plates in front of freeze-tolerant water channels made of silicon rubber.
Polymers, being flexible and therefore freeze-tolerant, are able to contain plain water instead of antifreeze, so that they may be plumbed directly into existing water tanks instead of needing to use heat exchangers which lower efficiency.
By dispensing with a heat exchanger in these flat plate panels, temperatures need not be quite so high for the circulation system to be switched on, so such direct circulation panels, whether polymer or otherwise, can be more efficient, particularly at low light levels.
Some early selectively coated polymer collectors suffered from overheating when insulated, as stagnation temperatures can exceed the melting point of the polymer. For example, the melting point of polypropylene is 160°C, while the stagnation temperature of insulated thermal collectors can exceed 180°C if control strategies are not used.
For this reason polypropylene is not often used in glazed selectively coated solar collectors. Increasingly polymers such as high temperate silicones (which melt at over 250°C) are being used. Some non-polypropylene polymer based glazed solar collectors are matt black coated rather than selectively coated to reduce the stagnation temperature to 150°C or less.
In areas where freezing is a possibility, freeze-tolerance (the capability to freeze repeatedly without cracking) can be delivered by the use of flexible polymers. Silicone rubber pipes have been used for this purpose in UK since 1999.
Conventional metal collectors are vulnerable to damage from freezing, so if they are water filled they must be carefully plumbed so they completely drain down using gravity before freezing is expected, so that they do not crack.
Many metal collectors are installed as part of a sealed heat exchanger system. Rather than having the potable water flow directly through the collectors, a mixture of water and antifreeze such as propylene glycol (which is used in the food industry) is used as a heat exchange fluid to protect against freeze damage down to a locally determined risk temperature that depends on the proportion of propylene glycol in the mixture. The use of glycol lowers the water’s heat carrying capacity marginally, while the addition of an extra heat exchanger may lower system performance at low light levels.
A pool or unglazed collector is a simple form of flat-plate collector without a transparent cover. Typically polypropylene or EPDM rubber or silicone rubber is used as an absorber. Used for pool heating it can work quite well when the desired output temperature is near the ambient temperature (that is, when it is warm outside). As the ambient temperature gets cooler, these collectors become less effective.
Most flat plate collectors have a life expectancy of over 25 years.
2. Evacuated Tube Collectors:
Most (if not all) vacuum tube collectors use heat pipes for their core instead of passing liquid directly through them. Evacuated heat pipe tubes (EHPT’s) are composed of multiple evacuated glass tubes each containing an absorber plate fused to a heat pipe.
The heat from the hot end of the heat pipes is transferred to the transfer fluid (water or an antifreeze mix—typically propylene glycol) of a domestic hot water or hydronic space heating system in a heat exchanger called a ‘manifold’. The manifold is wrapped in insulation and covered by a sheet metal or plastic case to protect it from the elements.
The vacuum that surrounds the outside of the tube greatly reduces convection and conduction heat loss to the outside, therefore achieving greater efficiency than flat-plate collectors, especially in colder conditions.
This advantage is largely lost in warmer climates, except in those cases where very hot water is desirable, for example commercial process water. The high temperatures that can occur may require special system design to avoid or mitigate overheating conditions.
Some evacuated tubes (glass-metal) are made with one layer of glass that fuses to the heat pipe at the upper end and encloses the heat pipe and absorber in the vacuum. Others (glass-glass) are made with a double layer of glass fused together at one or both ends with a vacuum between the layers (like a vacuum bottle or flask) with the absorber and heat pipe contained at normal atmospheric pressure.
Glass-glass tubes have a highly reliable vacuum seal but the two layers of glass reduce the light that reaches the absorber and there is some possibility that moisture will enter the non-evacuated area of the tube and cause absorber corrosion.
Glass-metal tubes allow more light to reach the absorber and protect the absorber and heat pipe (contained in the vacuum) from corrosion even if they are made from dissimilar materials (see galvanic corrosion).
The gaps between the tubes may allow for snow to fall through the collector, minimizing the loss of production in some snowy conditions, though the lack of radiated heat from the tubes can also prevent effective shedding of accumulated snow.
Comparisons of Flat-Plate and Evacuated Tube Collectors:
A long standing argument exists between protagonists of these two technologies. Some of this can be related to the physical structure of evacuated tube collectors which have a discontinuous absorbance area.
An array of evacuated tubes on a roof has:
(1) Open space between collector tubes, and
(2) (Vacuum-filled) space occupied between the two concentric glass tubes of each collector tube.
Consequently, a square meter of roof area covered with evacuated tubes (collector gross area) is larger than the area comprising the actual absorbers (absorber plate area). If evacuated tubes are compared with flat-plate collectors on the basis of area of roof occupied, a different conclusion might be reached than if the areas of absorber were compared.
In addition, the way that the ISO 9806 standard specifies the way in which the efficiency of solar thermal collectors should be measured is ambiguous, since these could be measured either in terms of gross area or in terms of absorber area. Unfortunately, power output is not given for thermal collectors as it is for PV panels. This makes it difficult for purchasers and engineers to make informed decisions.
Flat-plate collectors usually lose more heat to the environment than evacuated tubes and this loss increases with temperature difference. So they are usually inappropriate choice of solar collector for high temperature commercial applications such as process steam production.
Evacuated tube collectors have a lower absorber plate area to gross area ratio (typically 60-80% of gross area) compared to flat plates. (In early designs the absorber area only occupied about 50% of the collector panel.
However this has changed as the technology has advanced to maximize the absorption area). Based on absorber plate area, most evacuated tube systems are more efficient per square meter than equivalent flat plate systems. This makes them suitable where roof space is limiting, for example where the number of occupants of a building is higher than the number of square meters of suitable and available roof space.
In general, per installed square meter, evacuated tubes deliver marginally more energy when the ambient temperature is low (e.g., during winter) or when the sky is overcast for long periods. However even in areas without much sunshine and solar heat, some low cost flat plate collectors can be more cost efficient than an evacuated tube collectors.
Although several European companies manufacture evacuated tube collectors, the evacuated tube market is dominated by manufacturers in the East. Several Chinese companies have long favourable track records of 15-30 years. There is no unambiguous evidence that the two collector technologies (flat-plate and evacuated tube) differ in long term reliability.
However, the evacuated tube technology is younger and (especially for never variants with sealed heat pipes) still need to prove equivalent lifetimes of equipment when compared to flat plates. The modularity of evacuated tubes can be advantages in terms of extendibility and maintenance, for example if the vacuum in one particular tube diminishes.
For a given absorber area, evacuated tubes can therefore maintain their efficiency over a wide range of ambient temperatures and heating requirements. In most climates, flat-plate collectors will generally be a more cost-effective solution than evacuated tubes.
When employed in arrays, when considered instead on a per square meter basis, the efficient but costly evacuated tube collectors can have a net benefit in winter and also give real advantage in the summer months.
They are well suited to cold ambient temperatures and work well in situations of consistently low sunshine, providing heat more consistently than flat plate collectors per square meter. On the other hand, heating of water by a medium to low amount (i.e., Tm-Ta) is much more efficiently performed by flat plate collectors. Domestic hot water frequently falls into this medium category.
Glazed or unglazed flat collectors are the preferred devices for heating swimming pool water. Unglazed collectors may be suitable in tropical or subtropical environments if domestic hot water needs to be heated by less than 20°C. A contour map can show which type is more effective (both thermal efficiency and energy/cost) for any geographical region.
Besides efficiency, there are other differences. EHPT’s work as a thermal one-way valve due to their heat pipes. This also gives them an inherent maximum operating temperature which may be considered a safety feature. They have less aerodynamic drag, which may allow them to be laid onto the roof without being tied down.
They can collect thermal radiation from the bottom in addition to the top. Tubes can be replaced individually without shutting down the entire system. There is no condensation or corrosion within the tubes. There is the question of vacuum leakage over their lifetime. Flat panels have been around much longer and are less expensive. They may be easier to clean. Other properties, such as appearance and ease of installation are more subjective.
Solar Air Heat Collector:
Solar Air Heat collectors heat air directly, almost always for space heating. They are also used for pre-heating make-up air in commercial and industrial HVAC systems. They fall into two categories viz., Glazed and Unglazed.
Glazed systems have a transparent top sheet as well as insulated side and back panels to minimize heat loss to ambient air. The absorber plates in modern panels can have an absorptivity of more than 93%. Air typically passes along the front or back of the absorber plate while scrubbing heat directly from it. Heated air can then be distributed directly for applications such as space heating and drying or may be stored for later use.
Unglazed systems, or transpired air systems, consist of an absorber plate which air passes across or through as it scrubs heat from the absorber. These systems are typically used for pre-heating make-up air in commercial buildings.
These technologies are among the most efficient, dependable and economical solar technologies available. Payback for glazed solar air heating panels can be less than 9-15 years depending on the fuel being replaced.
Types of Solar Collectors for Electricity Generation:
Parabolic troughs, dishes and towers described in this section are used almost exclusively in solar power generating stations or for research purposes.
(i) Parabolic Trough:
This type of collector is generally used in solar power plants. A trough-shaped parabolic reflector is used to concentrate sunlight on an insulated tube (Dewar tube) or heat pipe, placed at the focal point, containing coolant which transfers heat from the collectors to the boilers in the power station.
(ii) Parabolic Dish:
It is the most powerful type of collector which concentrates sunlight at a single, focal point, via., one or more parabolic dishes—arranged in a similar fashion to a reflecting telescope focuses starlight, or a dish antenna focuses radio waves. This geometry may be used in solar furnaces and solar power plants.
There are two key phenomena to understand in order to comprehend the design of a parabolic dish. One is that the shape of a parabola is defined such that incoming rays which are parallel to the dish’s axis will be reflected toward the focus, no matter where on the dish they arrive.
The second key is that the light rays from the sun arriving at the Earth’s surface are almost completely parallel. So if dish can be aligned with its axis pointing at the sun, almost all of the incoming radiation will be reflected towards the focal point of the dish most losses are due to imperfections in the parabolic shape and imperfect reflection.
Losses due to atmosphere between the dish and its focal point are minimal, as the dish is generally designed specifically to be small enough that this factor is insignificant on a clear, sunny day. Compare this though with some other designs, and you will see that this could be an important factor and if the local weather is hazy or foggy, it may reduce the efficiently of a parabolic dish significantly.
In some power plant designs, a Stirling engine coupled to a dynamo, is placed at the focus of the dish, which absorbs the heat of the incident solar radiation and converts it into electricity.
(iii) Power Tower:
A power tower is a large tower surrounded by tracking mirrors called heliostats.
These mirrors align themselves and focus sunlight on the receiver at the top of tower, collector heat is transferred to a power station below:
Advantages of Power Tower:
i. Very high temperatures reached. High temperatures are suitable for electricity generation using conventional methods like steam turbine or some direct high temperature chemical reaction.
ii. Good efficiency. By concentrating sunlight current systems can get better efficiency than simple solar cells.
iii. A larger area can be covered by using relatively inexpensive mirrors rather than using expensive solar cells.
iv. Concentrated light can be redirected to a suitable location via., optical fiber cable. For example illuminating buildings.
v. Heat storage for power production during cloudy and overnight conditions can be accomplished, often by underground tank storage of heated fluids. Molten salts have been used to good effect.
Disadvantages of Power Tower:
i. Concentrating systems require sun tracking to maintain Sunlight focus at the collector.
ii. Inability to provide power in diffused light conditions. Solar cells are able to provide some output even if the sky becomes a little bit cloudy, but power output from concentrating systems drop drastically in cloudy conditions as diffused light cannot be concentrated passively.
Essay # 4. Electricity Generation Methods Using Solar Energy:
Sunlight can be converted into electricity using photovoltaics (PV), concentrating solar power (CSP) and various experimental technologies.
PV has mainly been used to power small and medium-sized applications, from the calculator powered by a single solar cell to off-grid homes powered by a photovoltaic array.
For large-scale generation, CSP plants (also called solar thermoelectric plants) like SEGS, have been the norm but recently multi-megawatt PV plants are becoming common. Completed in 2007, the 14 MW power station in Clark County, Nevada, United States and the 20 MW site in Beneixama, Spain are characteristic of the trend toward larger photovoltaic power stations in the United States and Europe.
As sometime an intermittent power source, solar power can require a backup supply, which can partially be complemented with wind power.
A solar pond is a pool of salt water (usually 1-2 m deep) that collects and stores solar energy. Solar ponds were first proposed by Dr. Rudolph Bloch in 1948 after he came across reports of a lake in Hungary in which the temperature increased with depth. This effect was due to salts in the lake’s water, which created a ‘density gradient’ that prevented convection currents.
A prototype was constructed in 1958 on the shores of the Dead Sea near Jerusalem. The pond consisted of layers of water that successively increased from a weak salt solution at the top to a high salt solution at the bottom. This solar pond was capable of producing temperatures of 90°C in its bottom layer and had an estimated solar-to-electric efficiency of two percent.
Thermoelectric or ‘thermovoltaic’ devices convert a temperature difference between dissimilar materials into an electric current. First proposed as a method to store solar energy by solar pioneer Mouchout in the 1800s, thermoelectrics reemerged in the Soviet Union during the 1930s.
Under the direction of Soviet scientist Abram loffe a concentrating system was used to thermoelectrically generate power for a 1 hp engine. Thermo generators were later used in the US space program as an energy conversion technology for powering deep space missions such as Cassini, Galileo and Viking. Research in this area is focused on raising the efficiency of these devices from 7-8% to 15-20%.
Essay # 5. Solar Power in India:
Fortunately, India lies in sunny regions of the world. Most parts of India receive 4-7 kWh of solar radiation per square meter per day with 250-300 sunny days in a year. India has abundant solar resources, as it receives about 3000 hours of sunshine every year, equivalent to over 5,000 trillion kWh. India can easily utilize the solar energy or solar power.
Solar power generation has lagged behind other sources like wind, small hydropower, biomass, etc. But now realizing the potential of solar energy, Prime Minister of India unveiled a National Climate Change Action Plan in June 2008. The plan will be implemented through eight missions with main focus on solar energy in the total energy mix of the country.
Government Authorities:
Development of alternate energy has been part of India’s strategy for expanding energy supply and meeting decentralized energy needs of the rural sector. The strategy is administered through India’s Ministry of New Renewable Energy (MNRE), Energy development agencies in the various states and the Indian Renewable Energy Development Agency Limited (IREDA).
MNRE:
Ministry of new renewable energy is the nodal ministry of the government of India for all matters relating to new and renewable energy. In 1982 Department of Non-conventional Energy Sources (DNES) was created to develop and deploy new and renewable energy for supplementing the energy requirements of the country. In 1992, DNES became the Ministry of Non-conventional Energy Sources.
In October 2006, the ministry was re-christened as the ministry of new and renewable energy. The ministry has been facilitating the implementation of broad spectrum programmes including harnessing renewable power, renewable energy to rural areas for lighting, cooking and motive power, use of renewable energy in urban, industrial and commercial applications and development of alternate fuels and applications. In addition, it supports research, design and development of new and renewable energy technologies, products and services.
IREDA:
Indian renewable energy development agency is a public limited Government company established on 11th March, 1987, under the administrative control of Ministry of New and Renewable Energy (MNRE) to promote, develop and extend financial assistance for renewable energy and energy efficiency/ conservation projects. IREDA has been notified as a &Idquo; Public Financial Institution & rdquo; under section 4 ‘ A&rsquo, of the companies Act, 1956 and registered as Non-banking Financial Company (NFBC) with Reserve Bank of India (RBI).
SEC:
The Solar Energy Centre (SEC), established in 1982, is a dedicated unit of the Ministry of New and Renewable Energy, Government of India for development of solar energy technologies and to promote its applications through product development. The institute was set up with a view to encourage research in the field of solar technology as a viable alternate energy system.
The centre itself is built taking into account principles of passive solar design to reduce energy consumption in the building. This is achieved by reducing heat gain in summer, encouraging effective ventilation, natural cooling and effective insulation to prevent heat loss during the winter, thus reducing both heating and cooling costs.
Involvement of various players in the energy sector, such as local industries. The private construction and operations contractors, Central Electricity Authority (CEA), MNRE and others, has helped in increasing the capacity and capability of local technical expertise and further sustain the development of solar power in India in the longer term.
Solar industry in India gained momentum with the contribution of private organizations. Many Indian companies have planned major investments in this industry. The government has approved projects of Chandradeep solar (for an R and D unit), Neotech Solutions, Photon Energy Systems, Surana Ventures and Ram Terra Solar Pvt. Ltd.
Tata Power and BP solar joint venture had been the leading Solar Photovoltaic (PV) manufacturers for the last many years. Moser Baer India Limited has entered the solar sector in a big way with both crystalline silicon cell technology and thin-film technology.
Khandelwal Solar Power Limited (KSPL):
Reliance Industries, Titan Energy Systems, Nano Tech Silicon India and XL Telecom & Energy also proposed to invest in the solar industry.
Present Status:
As a result of the efforts made during the past quarter century, a number of devices have been developed and have become commercially viable. These include solar water heaters, solar cookers, solar lanterns, solar street lights, solar water pumps.
India has started wide solar photovoltaic program for about 2 decades and has installed an aggregate 1.3 million systems. However, now the focus of the 11th year plan is on the grid connected power generation. India’s integrated rural energy program using solar energy had served 300 districts and around 2,300 villages.
Research and Development:
The Research and Development (R&D) efforts in the solar photovoltaic technology have been aimed at development of materials used in fabrication of solar cells and modules, different types of solar cell device structures, module designs, components, sub-systems and systems, with a view to reduce the cost and improve the overall efficiency at different stages.
The ministry has been sponsoring research and development projects on different aspects of the PV technology in academic and research institutions, national laboratories, IITs and industry, for development of new materials, processes, systems, production and testing equipment for solar cells and modules and electronics used in the PV systems.
There are number of R & D projects are going on solar PV program in India:
i. The solar energy centre has been established by Government of India as a part of MNRE to undertake activities related to design, development, testing, standardization, consultancy, training and information dissemination in the field of solar energy.
ii. Recently, development of polycrystalline silicon thin film solar cells and small area solar cells concluded at the Indian Association for Cultivation of Science at Jadavpur University.
iii. The National Physical Laboratory, New Delhi is working on development of materials and process to make dye sensitized nano-crystalline Ti02 thin films.
iv. The Centre for Materials for Electronics, Pune has been working on development of phosphorous paste for diffusion of impurities in solar cells.
v. Under a joint R&D project of MNRE and Department of Science and Technology (DST), the Indian Association for Cultivation of Science (IACS), Kolkata continued to work on optimization of process for fabrication of large area double junction amorphous silicon mod ales.
vi. Indian Institute of Science, Bangalore to develop efficient electronic system for connecting small PV systems to the grid.
vii. Indian Institute of Technology Bombay to work on development and testing of low concentration PV systems.
viii. The scientists at the Indian Association for Cultivation of Sciences, Jadavpur continued their work on development of nano and multi junction silicon thin film solar cells and optimization of the performance of multi junction thin film solar cells through computer modeling.
ix. A photo type solar car was successfully developed and demonstrated by the students of Delhi College of Engineering. The car operates on solar power, which is stored in storage batteries. In one charge the car is capable of travelling about 70 km. The maximum speed of the car was demonstrated at 60 km/hr. The solar car was also displayed in the 9th Auto Expo held in New Delhi during 10-17th January, 2009.
Essay # 6. Challenges and Constraints of Using Solar Energy:
(i) High Capital Cost:
The hunt for better, cheaper solar cells is due in India. Despite the fact that the price of solar photovoltaic technology has been coming down over the years it still remains economically unviable for power generation purposes. The average cost of solar PV modules was around Rs. 2 lakhs per kW.
However, the estimated unit cost of generation of electricity from solar photovoltaic and solar thermal route is in the range of Rs. 12-20 per kWh and Rs. 10-15 per kWh respectively in India. With present level of technology, solar electricity produced through the photovoltaic conversion route is 4-5 times costlier than the electricity obtained from conventional fossil fuels.
(ii) Manufacturing Process:
Solar PV cell manufacturing is a technology-intensive process requiring high expertise and know-how. Besides, the technology landscape in the solar industry PV space is changing quite rapidly with innovations and R&D. It is challenging for new entrants to replicate the success of companies having a long standing in the solar PV market.
(iii) Raw Material and Waste Products:
Some of the materials (like Cadmium) used for producing solar PV cells are hazardous and other raw materials like plastics used for the packaging of the cells are non-biodegradable, thereby impacting the environment. Although some of the wastage generated during the manufacturing process is recyclable (silicon), not all other materials are recyclable and disposal of the same is a challenging process.
(iv) Environmental Costs:
Another concern area is installing solar cells on the land area. The large amount of land required for utility-scale solar power plants – approximately one square kilometer for every 20-60 MW generated — poses an additional problem in India. Instead, solar energy in particular requires unique, massive applications in the agricultural sector, where farmers need electricity exclusively in the daytime. This could be the primary demand driver for solar energy in India.
In the very near future, break-through in nano technologies promise significant increase in solar cell efficiencies from current 15% values to over 50% levels. These would in turn reduce the cost of solar energy production.
However, capital costs have substantially declined over the past two decades, with solar PV costs declining by a factor of two. PV is projected to continue its current rapid cost reductions for the next decades to compete with fossil fuel. However, the realization of cost reductions is naturally closely linked to market development, government policies and support for research and development.