16-11-2012, 05:15 PM
Solar Photovoltaics
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Thin Film Technology
Silicon deposited in a continuous on a base material such as glass, metal or polymers
Thin-film crystalline solar cell consists of layers about 10μm thick compared with 200-300μm layers for crystalline silicon cells
Amorphous Silicon PV Cells
The most advanced of thin film technologies
Operating efficiency ~6%
Makes up about 13% of PV market
PROS
Mature manufacturing technologies available
CONS
Initial 20-40% loss in efficiency
Poly Crystalline PV Cells
Copper Indium Diselinide
CIS with band gap 1eV, high absorption coefficient 105cm-1
High efficiency levels
PROS
18% laboratory efficiency
>11% module efficiency
CONS
Immature manufacturing process
Slow vacuum process
PV’nomics
PV unit : Price per peak watt (Wp)
( Peak watt is the amount of power output a PV module produces at Standard Test Conditions (STC) of a module operating temperature of 25°C in full noontime sunshine (irradiance) of 1,000 Watts per square meter )
A typical 1kWp System produces approximately
1600-2000 kWh energy in India and Australia
A typical 2000 watt peak (2KWp) solar energy system costing $8000 (including installation) will correspond to a price of $4/Wp
Payback Time
Energy Payback Time:
EPBT is the time necessary for a photovoltaic panel to generate the energy equivalent to that used to produce it.
A ratio of total energy used to manufacture a PV module to average daily energy of a PV system.
At present the Energy payback time for PV systems is in the range
8 to 11 years, compared with typical system lifetimes of around 30 years. About 60% of the embodied energy is due to the silicon wafers.
The Other Side
Use newer and cheaper materials like amorphous silicon , CuInSe2 , CdTe.
Thin-film solar cells use less than 1% of the raw material (silicon) compared to wafer based solar cells, leading to a significant price drop per kWh.
Incentives may bring down the cost of solar energy down to 10-12 cents per kilowatt hour - which can imply a payback of 5 to 7 years.
Building Integrated systems
These systems use the existing grid as a back up, as the PV output falls or the load rises to the point where the PV's can no longer supply enough power
PV arrays can form an attractive facing on buildings and costs are equivalent to certain traditional facing materials such as marble with the advantage of generating free electricity.
Ideal for situations where peak electricity demand is during daytime such as commercial buildings.
Concluding Remarks
The key to successful solar energy installation is to use quality components that have long lifetimes and require minimal maintenance.
The future is bright for continued PV technology dissemination.
PV technology fills a significant need in supplying electricity, creating local jobs and promoting economic development in rural areas, avoiding the external environmental costs associated with traditional electrical generation technologies.
Major power policy reforms and tax incentives will play a major role if all the above said is to be effectively realized.