Technology
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Technologies such as photovoltaics are reinventing the definition of a power plant. Throughout Canada, most electrical grids rely on a few very large electricity generators in the 100s of MW each. Many industrialized countries around the world recognize the benefits of a more distributed generation system and provide incentives for smaller power plants that can be placed throughout the grid system and close to loads. Some grid operators find PV power plants a positive investment because of the correlation between PV production and peak power demand.
While PV power plants are a relatively new application for PV, they are growing rapidly and have the potential to provide a significant amount of electricity to grid systems. Until recently, the high cost and low levels of government support for PV and low cost and significant government support of alternatives made larger projects unattractive financially. Targets and requirements for renewable energy, tax incentives and feed in tariffs that pay producers of solar electricity a rate/kWh sufficient to generate a profit have incited the installation of a number of PV power plants in the past few years. The size of PV power plants has been increasing rapidly. About 1.1 GW of grid tied PV was installed in 2005 and several PV plants over 2 MW in size were constructed in 2006 (www.pvresources.com).
While similar to household sized PV systems, PV power plants as discussed here are installations in the tens of kW to the tens of MW, usually connected to the grid where the electricity is sold. PV power plants are also installed as backup systems, to charge batteries for critical loads and for large remote loads that are inaccessible to the grid. Photovoltaic power plants for the sale of electricity are growing in popularity, especially in jurisdictions with favourable government incentives. While solar thermal panels can produce electricity cheaper than PV panels, PV panels have other advantages. PV panels can still produce electricity on cloudy days, have fewer maintenance requirements, can be easily added to and built to any scale. PV panels convert the sun's energy directly into electricity. They are fairly simple systems that can be installed quickly and connect to the grid at almost any point. Some PV power plants are built as a series of PV panels on trackers in fields. The trackers adjust the angle of the panels throughout the day to 'track', or follow the path of the sun, increasing the power output and lengthening the time of day power is produced. Some PV power plants on trackers have been designed to minimize consistent shading of the land below to allow grazing or some crop growing to continue.
PV power plants are similar to grid tied household PV systems, only larger (see grid tied PV - link). The main components are the PV arrays and inverters. Inverters designed for PV power plants often have capacities in the 100s of kWs and can be 'stacked', with multiple inverters designed into one system. Other components include disconnects, meters and transformers for high voltage connection to the grid.
Modified: 02-18-2008
