Solar trackers increase the energy produced per module at the cost of mechanical complexity and increased need for maintenance. They sense the direction of the Sun and tilt or rotate the modules as needed for maximum exposure to the light. Alternatively, fixed racks hold modules stationary throughout the day at a given tilt (zenith angle) and facing a given direction (azimuth angle). Tilt angles equivalent to an installation's latitude are common. Some systems may also adjust the tilt angle based on the time of year. Similarly, to maximize total energy output, modules are often oriented to face south (in the Northern Hemisphere) or north (in the Southern Hemisphere). On the other hand, east- and west-facing arrays (covering an east–west facing roof, for example) may also be useful. Even though such installations might not produce the maximum possible total energy, their power output would likely be more consistent throughout the day and possibly larger during peak demand.
Some photovoltaic systems, such as rooftop installations, can supply power directly to an electricity user. In these cases, the installation can be competitive when the output cost matches the price at which the user pays for his electricity consumption. This situation is sometimes called 'retail grid parity', 'socket parity' or 'dynamic grid parity'. Research carried out by UN-Energy in 2012 suggests areas of sunny countries with high electricity prices, such as Italy, Spain and Australia, and areas using diesel generators, have reached retail grid parity.
More InfoIndia is home to two major language families: Indo-Aryan (spoken by about 74% of the population) and Dravidian (spoken by 24% of the population). Other languages spoken in India come from the Austroasiatic and Sino-Tibetan language families. India has no national language. Hindi, with the largest number of speakers, is the official language of the government. English is used extensively in business and administration and has the status of a "subsidiary official language"; it is important in education, especially as a medium of higher education. Each state and union territory has one or more official languages, and the constitution recognises in particular 22 "scheduled languages".
More InfoThe average life expectancy in India is at 68 years—69.6 years for women, 67.3 years for men. There are around 50 physicians per 100,000 Indians. Migration from rural to urban areas has been an important dynamic in India's recent history. The number of people living in urban areas grew by 31.2% between 1991 and 2001. Yet, in 2001, over 70% still lived in rural areas. The level of urbanisation increased further from 27.81% in the 2001 Census to 31.16% in the 2011 Census. The slowing down of the overall population growth rate was due to the sharp decline in the growth rate in rural areas since 1991. According to the 2011 census, there are 53 million-plus urban agglomerations in India; among them Mumbai, Delhi, Kolkata, Chennai, Bangalore, Hyderabad and Ahmedabad, in decreasing order by population. The literacy rate in 2011 was 74.04%: 65.46% among females and 82.14% among males. The rural-urban literacy gap, which was 21.2 percentage points in 2001, dropped to 16.1 percentage points in 2011. The improvement in the rural literacy rate is twice that of urban areas. Kerala is the most literate state with 93.91% literacy; while Bihar the least with 63.82%.
More InfoAveraging an economic growth rate of 7.5% for several years prior to 2007, India has more than doubled its hourly wage rates during the first decade of the 21st century. Some 431 million Indians have left poverty since 1985; India's middle classes are projected to number around 580 million by 2030. Though ranking 51st in global competitiveness, as of 2010, India ranks 17th in financial market sophistication, 24th in the banking sector, 44th in business sophistication, and 39th in innovation, ahead of several advanced economies. With seven of the world's top 15 information technology outsourcing companies based in India, as of 2009, the country is viewed as the second-most favourable outsourcing destination after the United States. India's consumer market, the world's eleventh-largest, is expected to become fifth-largest by 2030.
More InfoIn 1881, Charles Fritts created the first commercial solar panel, which was reported by Fritts as "continuous, constant and of considerable force not only by exposure to sunlight but also to dim, diffused daylight." However, these solar panels were very inefficient, especially compared to coal-fired power plants. In 1939, Russell Ohl created the solar cell design that is used in many modern solar panels. He patented his design in 1941. In 1954, this design was first used by Bell Labs to create the first commercially viable silicon solar cell. In 1957, Mohamed M. Atalla developed the process of silicon surface passivation by thermal oxidation at Bell Labs. The surface passivation process has since been critical to solar cell efficiency.
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