How Solar Power Plant Works

Solar power plant we visited is located at Keshegaon named as 1KW SOLAR POWER STATION, KESHEGAON. Here the power is created using the solar power plates. The detailed process is as follows -

When light hits the solar panels, the solar radiation is converted into direct current electricity (DC). The direct current flows from the panels and is converted into alternating current (AC) used by local electric utilities. Finally, the electricity travels through transformers, and the voltage is boosted for delivery onto the transmission lines so local electric utilities can distribute the electricity to homes and businesses.

There are two main ways of generating energy from the sun. Photovoltaic (PV) and concentrating solar thermal (CST), also known as concentrating solar power (CSP) technologies.

PV converts sunlight directly into electricity. These solar cells are usually found powering devices such as watches, sunglasses and backpacks, as well as providing power in remote areas.

Solar thermal technology is large-scale by comparison. One big difference from PV is that solar thermal power plants generate electricity indirectly. Heat from the sun's rays is collected and used to heat a fluid. The steam produced from the heated fluid powers a generator that produces electricity. It's similar to the way fossil fuel-burning power plants work except the steam is produced by the collected heat rather than from the combustion of fossil fuels.

How Solar Works

We can change sunlight directly to electricity using solar cells. Every day, light hits your roof's solar panels with photons (particles of sunlight). The solar panel converts those photons into electrons of direct current ("DC") electricity. The electrons flow out of the solar panel and into an inverter and other electrical safety devices. The inverter converts that "DC" power (commonly used in batteries) into alternating current or "AC" power. AC power is the kind of electrical that your television, computer, and toasters use when plugged into the wall outlet.

A net energy meter keeps track of the all the power your solar system produces. Any solar energy that you do not use simultaneous with production will go back into the electrical grid through the meter. At night or on cloudy days, when your system is not producing more than your building needs, you will consume electricity from the grid as normal. Your utility will bill you for the "net" consumption for any given billing period and provide you with a dollar credit for any excess during a given period. You can carry your bill credit forward for up to a year.

Solar Cells

Solar cells are small, square-shaped panel semiconductors made from silicon and other conductive materials, manufactured in thin film layers. When sunlight strikes a solar cell, chemical reactions release electrons, generating electric current. Solar cells are also called photovoltaic cells or "PV cells" and can be found on many small appliances such as calculators.

Solar Photovoltaic (PV) System Components

A PV system components include PV modules (groups of PV cells), which are commonly called PV panels; one or more batteries; a charge regulator or controller for a stand-alone system; an inverter to covert solar power from direct current (DC) to the alternating current (AC) of the utility grid-connected system; wiring; and mounting hardware or a framework. A PV module arranges individual PV cells, and the modules are grouped together in an array. Some of the arrays are set on special tracking devices to follow sunlight all day long and improve system efficiency.

PV System Installation, Maintenance, and Longevity

You could install a photovoltaic (PV) or solar electric system yourself. But to avoid complications or injury, you will probably want to hire a reputable professional contractor with experience installing solar systems. While they are sophisticated electric systems, PV systems have few moving parts, so they require little maintenance. The basic PV module (an interconnected, enclosed panel of PV cells) has no moving parts and can last more than 30 years while requiring little maintenance. The components are designed to meet strict dependability and durability standards to withstand the elements. The best way to ensure and extend the life and effectiveness of your PV system is by having it installed and maintained properly. Most PV system problems occur because of poor or sloppy system installation.

Incorporating PV Systems into Your Home and Business

PV systems today can be blended easily into both traditional and nontraditional homes, powering appliances and electric systems. PV cells can be installed as a stand-alone module that is attached to your roof or on a separate system, or using integrated roofing materials with dual functions - that as a regular roofing shingle and as a solar cell making electricity. The most common practice is to mount modules onto a south-facing roof or wall. PV systems likewise can be blended into virtually every conceivable structure for commercial buildings. You will find PV used outdoors for security lighting as well as in structures that serve as covers for parking lots and bus shelters.

Sunlight Requirements for PV Systems

A photovoltaic (PV) system needs unobstructed access to the sun's rays for most or all of the day to be effective. Shading on the system can significantly reduce energy output. Climate is not a major concern because PV systems are relatively unaffected by air temperatures, and snow cover typically melts quickly because panels are positioned directly into the sunlight. Abundant year-round sunshine makes solar energy systems useful and effective nearly everywhere.

The Size of Your Solar PV System

The size of your solar system depends on several factors such as how much electricity or hot water or space heat you use, the size of your roof, how much you're willing to invest, and how much energy you want to generate.

Other Solar Technologies

• Concentrating solar power (CSP) systems concentrate the sun's energy using reflective devices such as troughs or mirror panels to produce heat that is then used to generate electricity.
• Solar water heating systems contain a solar collector that faces the sun and either heats water directly or heats a "working fluid" that, in turn, is used to heat water. For more information on installing a solar water heating system, please see the CSI Solar Thermal section of the Go Solar California website.
• Transpired solar collectors, or "solar walls," use solar energy to preheat ventilation air for a building.

Reference

http://www.nexteraenergyresources.com/home/index.shtml

http://www.solartechnologies.com/

http://www.gosolarcalifornia.ca.gov/

http://home.howstuffworks.com/home-improvement/green-living-pictures.htm

http://vicgurav.blogspot.in/

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WDM Technology

WDM

(Wavelength Division Multiplexing)

Wavelength division multiplexing is a technique where optical signals with different wavelengths are combined, transmitted together, and separated again. It is mostly used for optical fiber communications to transmit data in several (or even many) channels with slightly different wavelengths. In this way, the transmission capacities of fiber-optic links can be increased strongly, so that most efficient use is made not only of the fibers themselves but also of the active components such as fiber amplifiers. Apart from telecom, wavelength division multiplexing is also used for, e.g., interrogating multiple fiber-optic sensors within a single fiber.

The idea of wavelength multiplexing relies on the principle that light of a certain wavelength does not interfere with light of another wavelength. For every data channel an independent laser is used. The light of each laser is combined to a single beam and fed into the fiber optic cable.

To be able to demultiplex the data at the far end, both channels need to use a distinct wavelength that is non-overlapping. For this purpose ”color” filters are used to split the light according to wavelength and thus decode the data channels. Of course we are talking about invisible light and hence the term color does not really apply.

WDM in Telecom Systems

Theoretically, the full data transmission capacity of a fiber could be exploited with a single data channel of very high data rate, corresponding to a very large channel bandwidth. However, given the enormous available bandwidth (tens of terahertz) of the low-loss transmission window of silica single-mode fibers, this would lead to a data rate which is far higher than what can be handled by optoelectronic senders and receivers. Also, various types of dispersion in the transmission fiber would have very detrimental effects on such wide-bandwidth channels, so that the transmission distance would be strongly restricted. Wavelength division multiplexing solves these problems by keeping the transmission rates of each channel at reasonably low levels (e.g. 10 Gbit/s) and achieving a high total data rate by combining several or many channels.

Two different versions of WDM, defined by standards of the International Telecommunication Union (ITU), are distinguished:

Coarse wavelength division multiplexing (CWDM, ITU standard G.694.2) uses a relatively small number of channels, e.g. four or eight, and a large channel spacing of 20 nm. The nominal wavelengths range from 1310 nm to 1610 nm. The wavelength tolerance for the transmitters is fairly large, e.g. ±3 nm, so that unstabilized DFB lasers can be used. The single-channel bit rate is usually between 1 and 3.125 Gbit/s. The resulting total data rates are useful e.g. within metropolitan areas, as long as broadband technologies are not widespread in households.

Dense wavelength division multiplexing (DWDM, ITU standard G.694.1) is the extended method for very large data capacities, as required e.g. in the Internet backbone. It uses a large number of channels (e.g. 40, 80, or 160), and a correspondingly small channel spacing of 12.5, 25, 50 or 100 GHz. All optical channel frequencies refer to a reference frequency which has been fixed at 193.10 THz (1552.5 nm). The transmitters have to meet tight wavelength tolerances. Typically, they are temperature-stabilized DFB lasers. The single-channel bit rate can be between 1 and 10 Gbit/s,and in the future also 40 Gbit/s.

Due to the wide amplification bandwidth of erbium-doped fiber amplifiers, all channels can often be amplified in a single device (except in cases where e.g. the full range of CWDM wavelengths is used). However, problems can arise from the variation of gain with wavelength or from interaction of the data channels (crosstalk, channel interference) e.g. via fiber nonlinearities. Enormous progress has been achieved with a combination of various techniques, such as the development of very broadband (double-band) fiber amplifiers, gain flattening filters, nonlinear data regeneration and the like. The system parameters such as channel bandwidth, channel spacing, transmitted power levels, fiber and amplifier types, modulation formats, dispersion compensation schemes, etc., need to be well balanced to achieve optimum overall performance.

Even for existing fiber links with only one or a few channels per fiber, it can make sense to replace senders and receivers for operation with more channels, as this can be cheaper than replacing the whole system with a system with a higher transmission capacity. In fact, this approach often eliminates the need to install additional fibers, even though the demand on transmission capacities is increasing enormously.

Apart from increasing the transmission capacity, wavelength division multiplexing also adds flexibility to complex communication systems. In particular, different data channels can be injected at different locations in a system, and other channels can be extracted. For such operations, add–drop multiplexers can be used, which allow one to add or drop data channels based on their wavelengths. Reconfigurable add–drop multiplexers make it possible to reconfigure the system flexibly so as to provide data connections between a large number of different stations.

In many cases, time division multiplexing (TDM) can be an alternative to wavelength division multiplexing. Here, different channels are distinguished by arrival time rather than by wavelength.

Drawbacks

One the drawbacks of all currently available WDM systems is the fact that wavelength selected lasers cannot be tuned to a certain wavelength after they have been installed. Therefore, a dedicated channel card is required for every wavelength. This makes stocking, especially for immediate exchange in the event of a failure, costly and cumbersome. It can be expected that improvements in the laser technology will eliminate that disadvantage within the next few years.

Conclusion

WDM is an extremely attractive technology that has already changed the way optical networks are designed today. Future improvements will bring the cost further down and increase channel counts. 

For cost sensitive application CWDM with a coarse channel spacing and a limited number of channels are the way to go. When higher capacity and future expandability is a must, TDM and CWDM or DWDM combinations offer the best price/performance.

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Book: The Google Story

The Google Story

Google Inc. is an American multinational corporation specializing in Internet-related services and products. But it is well known to all people as the largest using search engine.

Google began in January 1996 as a research project by Larry Page and Sergey Brin when they were both PhD students at Stanford University in Stanford, California. 

The Google Story is a book by David A. Vise and Mark Malseed about the Internet success of Google. It is the story of Google's founders; Sergey Brin and Larry Page, and starts with how they dropped out of graduate school at Stanford University before creating the search engine.

The book describes that, how Sergey Brin and Larry Page created the google and what difficulties comes on their path, This is the story behind the google. Here is the story behind one of the most remarkable Internet successes of our time. Based on scrupulous research and extraordinary access to Google, the book takes you inside the creation and growth of a company whose name is a favorite brand and a standard verb recognized around the world.

Author : David A. Vise, Mark Malseed

Subject : Web search engine, Google

Publisher : Delacorte Press

Publication date : November 15, 2005

Download this book at free of cost :

Download Book: The google Story

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