A Field of Mirrors

When the Abengoa Solana CSP plant went online in October of 2013, it was the largest working parabolic trough plant in the world (since surpassed). Solana covers more than 1,900 acres in central Arizona and it created over 2,000 construction jobs and 85 permanent jobs. These numbers do not take into effect the number of indirect jobs created as a result of the injection of capital into the community and state.

Arizona Public Service, the state’s largest electric utility, has contracted to purchase all the power generated by Solana for 30 years. On a daily basis, APS determines how Solana should produce and store its energy in order to best meet local demand. The 3,200 concave mirrors concentrate light onto the heat transfer fluid, heating it to 740 degrees Fahrenheit. About 270 miles of pipe transport the fluid to the power block where it can either be sent to the steam generator to boil water and create steam to drive two 140 megawatt turbines, or it can be sent to one of 12 giant salt tanks to be stored for later use. The salt tanks can hold the heat from the fluid for up to six hours. When electricity is needed, the heat in the hot salt is transferred into another holding tank where it is converted into steam to produce electricity.

One major drawback of CSP plants like Solana is that they need significant water for their cooling operations; however, the project’s land was previously designated for agriculture and the plant uses 75% less water for solar energy production than its previous designation.

Abengoa estimates that under optimal conditions, Solana can produce enough electricity to power 70,000 homes.

Solar Cooking


Solar cookers are simple, low cost and effective.  They are basically insulated enclosures with a clear top to allow sunshine to enter.  The sunshine is absorbed by both the food and a black surface, heating up the enclosure and cooking the food. Reflectors can be used to increase heating by allowing more sunshine to enter the cooker.

Learn more about solar cookers by following the links below.

Photovoltaics Birth

The Birth of a Technology

In 1955, using crystalline silicon, scientists at Bell Laboratories fashioned an enormous solar cell capable of turning six percent of the sunlight that struck it into electricity. Soon the efficiency was raised to eleven percent and scientists realized that the new devices could have practical applications. They had another reason for optimism; the material they were using, silicon, is the world’s second most abundant element, comprising 28 percent of the earth’s crust.

These achievements were greeted with much fanfare amid the technological developments of the 1950s. Solar cells seemed to promise an unlimited supply of electricity and roused considerable excitement. A 1957 article in “Business Week” envisioned an automatically controlled solar car in which “all riders could sit comfortably in the back seat and perhaps watch solar-powered TV.”

U.S. News and World Report said that the silicon solar cell "may provide more power than all the world's coal, oil and uranium."

The New York Times said the discovery "may mark the beginning of a new era, leading eventually to the realization of one of mankind's most cherished dreams -- the harnessing of the almost limitless energy of the sun for the uses of civilization."

It was an unfavorable time, however, to develop a new energy technology. Oil was priced at less than $2 per barrel, and large fossil-fuel power plants were being built at a record pace. Moreover, in 1954 construction began on the world’s first commercial nuclear reactor. Nuclear power was envisioned as a source of electricity “too cheap to meter,” and most government energy funds were devoted to that technology.

Photovoltaic researchers also faced an unsettling economic reality. Silicon cells developed in the 1950s were extremely expensive, with costs as high as $600 per watt (compared to less than $1 today). Funding for research to reduce the cost was not available in an era with falling electricity prices and minimal concerns about the environment.

The space program rescued photovoltaics from the technological scrap heap. American scientists in the late 1950s went searching for a lightweight, long-lasting power source for satellites. Photovoltaic cells, which could take advantage of the continuous sunlight of space, were their choice. In 1958 just four years after the Bell laboratory breakthrough, silicon solar cells were boosted into orbit aboard Vanguard I, the second U.S. Satellite.

With the help of large contracts from the National Aeronautics and Space Administration (NASA) four U.S. commercial companies enter the photovoltaics business and by the late 1960’s were producing hundreds of thousands of solar cells a year. Amid the heady competition of the post-sputnik space race, the Soviet Union began equipping its satellites with photovoltaics as well. Today, solar cells power virtually all satellites.

Achievements in photovoltaic cell research during the peak years of the space program included a major increase in efficiency and reduction in cost. However, the space-related PV market leveled-off and photovoltaic cell production declined.

In 1973, America was jolted by its first oil crisis – gasoline prices soared and interest in alternative fuels was awakened. Beginning in 1975, the U.S. government funded a steadily growing research and development program aimed at making photovoltaics economical for terrestrial use. Japan and European countries followed suit. Perhaps a dozen private companies entered the solar cell research or production business.

Over the next quarter century, the overall market for photovoltaic technology increased dramatically. In the last five years alone, from 2010 to 2015, more photovoltaic systems have been deployed than in the five previous decades coming after the Bell Labs discovery.

• Report on PV - Fundamentals (Eliminate the material that dates it like the 60 watt panel references and just keep the info on "How a Cell Works".