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AAEA Strongly Supports Solar Cells

Converting sunlight into electricity is more fascinating than  converting uranium radioactivity into electricity.  Both electricity generation processes are extremely appealing to us because they are emission free.  Of course, nuclear purrs along day or night, cloudy or clear.  We need to start building a 'smart grid' that can handle distributed generation sources of power such as that provided by photovoltaic (PV) arrays.  Currently, our electrical grids are dumb and blind and distribute alternating current through inefficient copper and silver wires.  Line losses of electricity, due to blockages to electron flow through impure metals, can be as high as 60 percent.  A description of how photovoltaics work:

 

When photons strike a PV cell, the absorbed photons generate electricity. When this happens, the energy of the photon is transferred to an electron in an atom of the cell. With its newfound energy, the electron is able to escape from its normal position associated with that atom to become part of the current in an electrical circuit.

Unfortunately, signifcant land area is required for photovoltaic arrays or solar power towers to generate electrical capacity comparable to other central systems. In terms of solar-powered generation, the land requirements are 35,000 acres (55 square miles) per 1,000 MW for photovoltaic and 14,000 (22 square miles) acres per 1,000 MW for solar thermal systems.  Of course, photovoltaics can still provide significant supplemental supplies of electricity by covering areas already covered by buildings and other impervious surfaces.

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Grid-connected or utility-interactive PV systems are designed to operate in parallel with and interconnected with the electric utility grid. The primary component in grid-connected PV systems is the inverter, or power conditioning unit (PCU). The PCU converts the DC power produced by the PV array into AC power consistent with the voltage and power quality requirements of the utility grid, and automatically stops supplying power to the grid when the utility grid is not energized. A bi-directional interface is made between the PV system AC output circuits and the electric utility network, typically at an on-site distribution panel or service entrance.

 

This allows the AC power produced by the PV system to either supply on-site electrical loads, or to back feed the grid when the PV system output is greater than the on-site load demand. At night and during other periods when the electrical loads are greater than the PV system output, the balance of power required by the loads is received from the electric utility This safety feature is required in all grid-connected PV systems, and ensures that the PV system will not continue to operate and feed back onto the utility grid when the grid is down for service or repair.

Sources: FSEC, National Energy Laboratory, DOE  

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