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| news archive | |
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Fall 2005 Newsletter |
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In this issue: |
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Solar power - a brilliant choice |
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Each day the sun provides the light and heat which are essential to human existence. But in recent decades, technology has given the sun a new potential mission – as a clean, abundant power source. Sunlight - or solar energy - has been gaining momentum as a source of electricity since its first appearance in the 1970’s. Most likely you’ve seen solar-powered calculators or solar panels on rooftops for heating homes. This same solar power can also be used to generate larger amounts of electricity. |
 A special multi-part series highlighting the resources of the NC GreenPower program. |
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The panels are made of semiconducting materials similar to those used in computer chips. When sunlight is absorbed by these materials, the solar energy knocks electrons loose from their atoms, allowing the electrons to flow through the material to produce electricity. This process of converting light (photons) to electricity (voltage) is called the photovoltaic (PV) effect. Solar cells are typically combined into modules that hold about 40 cells; about 10 of these modules are mounted in PV arrays that can measure up to several meters on a side. These flat-plate PV arrays can be mounted at a fixed angle facing south, or they can be mounted on a tracking device that follows the sun, allowing them to capture the most sunlight over the course of a day. About 10 to 20 PV arrays can typically provide enough power for a household. Because the electricity produced by PV arrays is in the form of direct current, if the electricity is supplied to the electric power grid, the arrays need to be coupled to an inverter which changes the direct current into alternating current. Once converted to the appropriate voltage and frequency, the electricity can be supplied to the electric grid.
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Solar power benefits and challenges |
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And while recent technologies have enabled these emissions to be drastically reduced, they cannot approach the cleanliness of solar power. Solar power is also a reliable, abundant source of power that will never run out, unlike fossil fuels which take millions of years to replenish and are finite in their supply. They are quiet and therefore unobtrusive when used to produce electricity in a residential or commercial environment. They can provide localized or grid-tied power that can reduce dependence on energy resources from other states and countries. And solar panels have no moving parts, which means that properly maintained panels can potentially last for up to 30 years or more. Despite their many benefits, photovoltaic systems also provide some challenges. The most notable challenge is the amount of electricity a solar array can produce when compared to the overall size of the installation. Producing enough electricity for large-scale industrial applications would require major quantities of panels, provided at both a cost and surface area premium. While technology costs are only a fraction of what
they were 30 years ago, homeowners may find that a home-based photovoltaic
system can cost between 20-30 thousand dollars to install. And solar
costs are all captured upfront in the cost of the equipment, so
the per-kilowatt-hour costs can far outpace what retail electricity
costs the consumer. It is estimated that the per-kilowatt-hour cost
of generating electricity from solar PV panels ranges on average
from 24-29 cents per kWh. |
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| As of August 2005 Program participation Current NC GreenPower subscribers – 6,987 Total monthly NC GreenPower blocks subscribed – 17,049 Annual equivalent blocks subscribed – 204,591 Annual equivalent energy – 20,459,100 kWh Environmental offsets The generation of this amount of renewable energy will annually offset:
Energy equivalents
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