subject: Utility Scale Solar Power [print this page] Solar radiation is an amazing, endless energy source for use through a wide variety of technologies. In fact, the sun supplies enough energy each hour to power the planet for one year! Although we are acquainted with smaller applications of this energy, such as a solar-powered calculator, a solar panel to heat water for a home, or perhaps even a solar car; it is also possible to provide solar power energy on a large scale, such as the power produced by a solar power plant. In this case, the solar power plant could work like any other energy utility and supply electricity to consumers within a realistic distance from the plant. There are two fundamental forms of utility scale solar power technology:
Concentrating Solar Power (CSP) Technologies
Just like the name infers, a concentrating solar power technology generates power by concentrating the rays of the sun, often with mirrors. In turn, the mirrors are used to heat up fluids (and sometimes solids), which are then used as steam to operate turbines and other power-producing equipment. There are several sub-types of this technology: trough systems, which use U-shaped focusing mirrors that have oil pipes running through them. Basically, sunlight heats up the oil, which is then utilized to boil water to make steam that drives machinery. A power tower system, on the other hand, uses flat mirrors to track the sun and focus its rays onto a receiver on the top of a tower. Here, the sunlight heats a liquid (typically molten salt) which in turn produces steam that produces electrical energy. Since molten salt stores heat, it can be used on days when there is cloud cover or even after dark. Lastly, dish/engine systems are mirrored dishes that track the sun throughout the day, capture light and concentrate it on to a receiver. The receiver is part of a combustion engine which has tubes of helium or hydrogen gas running through it. Once the gas is heated by the sun's rays, it expands and drives pistons, which power an electric generator.
Photovoltaic (PV) Technologies
One of the most popular systems, PV technology converts the suns rays directly to electric power as opposed to converting it to heat which then yields power. Solar cells are one form of Photovoltaic technology. In this case, the cells are made of semiconductor materials which, when heated by the sunlight, cause electrons to flow through the material and produce electric power. Solar cells are too small for utility purposes, however. Solar arrays, in contrast, combine modules of about 40 cells into arrays which can be meters long on
each side. To generate sufficient power for a utility, many arrays would combine to form one large system. Lastly, a concentrated PV system focuses the suns light on cells using a lens or mirror. They provide high efficiency, low cost and can scale up very quickly, leading them to be a great choice for utility scale usage.
