Power Electronics in Alternative Energy

Wind, water, and sunlight are the keys to a new generation of power sources. However this raw power must be conditioned before it can be used by standard electrical loads. This power conditioning function is where power electronics play an important role.

Solar power is generally used to convert the sun's energy into two more readily useable forms: hot liquid such as in a solar water heating plant, and electrical current such as generated by photovoltaic cells. Hot liquid systems can be used to generate steam to drive turbines and DC generators. These systems can then use static power inverters to create AC power suitable to run a given load or to feed into the power grid.

The electrical current available from photovoltaic systems is supplied at very low voltages that depend on a number of factors including the angle of the sunlight and level of cload cover. This variation of output voltage and output power means that we need some way of regulating controlling the output of the photovoltaic system; this task is often accomplished using adjustable boost converters that can keep the output voltage of a solar cell bank constant regardless of sun angle. Once a constant voltage is available, an inverter converts the solar power to AC so it can be fed into the power grid.

Photovoltaic current is now more than ever becoming a growing source of power. Thanks to recent developments in thin film photovoltaics the cost per kilwatthour is approaching the national average of 8 cents/kWhr.

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