dip a brush Into SUN and paint a window towards Eternity
A solar PV is semiconductor based technology and converts sunlight directly into electricity via photoelectric effect. Today the contribution of Solar PV is 0.1% but it is assumed that by 2050 Solar PV will account to 11% of the world’s energy needs and will reduce 2.3Gt gigatonnes of CO2 emissions per year. An estimated 3 million throughout the world currently benefit from small Solar PV systems. Prices reduced by 50-60% in 2009 in comparison to 2008. During the same time lowest prices reported for PV modules were less than $2/W With the prices falling so sharply a shift was seen from excess demand to excess supply. With more R&D and investments flowing in, the efficiency is set to increase and cost per Watt will also come down. According to an EPA study it was shown that 1kW of PV can offset between 600-2300 kg of CO2 per year with substantial amount of other pollutant .
India has a present 2.9MW off-grid capacity from Solar PV energy systems and is bound to go up drastically with the launch of Jawaharlal Nehru National Solar Mission . India currently has 4 major PV plants connected to the grid in West Bengal, Maharashtra, Karnataka and Punjab. New projects for addition of 1400 MW are coming up in Andhra Pradesh, Gujarat and Rajasthan, with a major chunk of it (1000 MW) will be installed in Andhra Pradesh .
A Solar PV provides low output when compared to the cost involved. Components like inverters, batteries, mountings and other electrical appliances escalate the price of the system. The cost may infact depend on local factors such as size, location (amount of solar irradiance), customer type, purpose and discount/interest factors. Prices for off-gird applications are seen to be roughly double than grid-connected applications. The prices in 2009 were seen to be nearly $10/Watt for off-grid applications and $4/Watt to $6/Watt to grid applications .
The efficiency will increase and cost per watt will decrease in years to come, thus also decreasing the pay-back time. The efficiency depends on the technology and the material used. The technologies can be broadly divided into 5 types:
The technological targets set for Solar PV have been found out to be
|Flat Plate Module Efficiency||16%||23%||25%||40%|
|Payback time for 1500kWh/kWp||2 years||12 months||8 months||6 months|
|Operational Lifetime||25 years||30 years||35 year||40 year|
Source: Technology Roadmap, Solar Photovoltaic Energy, IEA
The solar photovoltaic technology may actually require a detailed study before installations. Atypical solar panel may vary from 0.5 -2 sq. meters in size with an approximate weight of 15-20 kg/meter square. To its advantage it does utilize both direct and diffused part of the sunlight but has other drawbacks. A system marked as 100 Watt at STC conditions may actually only be able to provide an output of 67.5 Watt on a clear sky day. Factors affecting the performance are internal heating, dust, mismatch and wiring loss and DC-AC conversion. The reduction factors for each of them are generally taken as 0.89, 0.93, 0.95 and 0.90 respectively. If a battery is added to the system the output may further reduce be 6-10%. The time of the day as well as position of the array may affect the output; the output will slowly rise to maximum at afternoon and decrease back to zero at night. According to the orientation the panel a correction factor may creep in with values ranging from 0.80 to 1.00 . Thus with a tolerance factor of 5% the output of the plant at clear sky conditions with no battery backup and correction factor as 1 the output can be roughly assumed to be 67.5 Watt.
Energy consumption may vary from very modest 3000kWhr/year to 20,000 KWhr/year at a very large home with heavy electrical usage. A solar PV can to be used to satisfy the total energy need or can be primarily used to reduce the electrical bill. A 1kW installation may be sufficient to satisfy the need of a home without an air-conditioner but may need an investment of upto 3-5 lakh Rupees for the total system.
A Solar Panel May give an annual output of 1400-1750 kWhr/kWstc with an average insolation of 5.5kWhr/sq. meter. Thus a 3kW system may generate upto 4000 kWhr/year (3×0.95×1400= 3990), sufficient for a single household but the whole system can cost upto Rs 10-15 lakh. Subsidies have been provided for non-profit making bodies upto of Rs 100/Watt (to a maximum of 40% of the cost of system) for installations between 25 to 100 kW. With easy loans and low rate of interest solar energy can go a long way for making families self-sufficient and even help in rural upliftment thus increasing the quality of life of an average human being.