March 11, 2008

Energy - Large Scale Solar Farms

Sarah Sandman

How Solar Power Works
Converting Photons to Electrons

"The solar cells that you see on calculators and satellites are photovoltaic cells or modules (modules are simply a group of cells electrically connected and packaged in one frame). Photovoltaics, as the word implies (photo = light, voltaic = electricity), convert sunlight directly into electricity. Once used almost exclusively in space, photovoltaics are used more and more in less exotic ways. They could even power your house. How do these devices work?

Photovoltaic (PV) cells are made of special materials called semiconductors such as silicon, which is currently the most commonly used. Basically, when light strikes the cell, a certain portion of it is absorbed within the semiconductor material. This means that the energy of the absorbed light is transferred to the semiconductor. The energy knocks electrons loose, allowing them to flow freely. PV cells also all have one or more electric fields that act to force electrons freed by light absorption to flow in a certain direction. This flow of electrons is a current, and by placing metal contacts on the top and bottom of the PV cell, we can draw that current off to use externally. For example, the current can power a calculator. This current, together with the cell’s voltage (which is a result of its built-in electric field or fields), defines the power (or wattage) that the solar cell can produce."

What are Photovoltaic Power Plants?

"Photovoltaic power plants - Solar modules are nowadays parts of large standalone or grid-connected systems. Large photovoltaic power plants (MW range) have beeing constructed in Germany, Spain, USA, Italy, Netherlands etc. Worldwide more than 250 large PV power plants with peak power 1 MWp or more (each plant) are connected to the public grid(s)."

Worldwide Photovoltaic Power Plant Breakdown

"80% of all large photovoltaic plants (power related) are installed in Europe (700 MWp). The share of the USA accounts about 16 % (142 MWp) and in Asia 4 % (34 MWp) are installed. At present Germany hosts nearly 50 % of the world’s installed photovoltaic power, but its market share was decreasing slowly within the last months.

The most dynamic market is Spain - where an extreme increase of installed power has been observed in 2007. In the last decade only the USA and Germany created a steady growth of their photovoltaic market. The fast growth in Spain started about three years ago and led to an extreme increase in 2007. Further progress is visible in Europe and in South Korea. Italy, particulate France, and Greece turn out to be auspicious markets. The rest of the world (i.e. Africa, South America and Australia) represents less than 1 % of global installed PV power but shows significant potentials for future solar energy use in these regions.

Countries with cumulative installed power more than 1 MW of large photovoltaic power plants (> 200 kWp each considered plant) are listed in Table 2 a the end of this report. Germany leads with more than 400 MW, followed by Spain (almost 250 MW) that displaced the USA (140 MW) at the second position. Italy and Japan (each about 17 MW) Korea (13 MW) and Portugal (12 MW) anyhow reached two digit figures. Countries with less than 1 MWp installed are Thailand, France (without overseas territories), United Kingdom, Malaysia, Saudi Arabia, Luxembourg, Rwanda, India and Mexico.

Primary PV world markets are still Germany with about 45 % of the installed power, followed by Spain (28 %) and the USA with 16 % market share. Spain proved as the most dynamic PV market with an impressive growth that might be probably lower this year. The average installed capacity of a single large commercial power plant has increased from 400 kWp in 1997 to 1,64 MWp in 2007. The average capacity of sole commercial PV plants accounts for 1,14 MWp."

Parque Solar Hoya de Los Vincentes
Jumilla, Spain

January 31, 2008

"With an installed peak power of 20 MW, the solar park at Jumilla, Murcia (Southeastern Spain) is the world’s current highest capacity PV plant and the most efficient to-date.

It took a team of 400 people 11 months to build the Jumilla plant, where 120,000 solar panels are grouped into 200 separate photovoltaic arrays -owned by different investors- to convert light from the sun into electricity. It’s expected to generate an estimated annual income of $28 million (€19 million) and a reduction in CO2 emissions of 42,000 tons a year.

The plant covers an area of 100 hectares in La Hoya de Vicentes, Jumilla, (see picture) where the local Mayor says 300 days of sun a year are guaranteed. Its total annual production will be the equivalent of the energy used by 20,000 homes.

Different measures were taken following the recommendations from a local association, Juncellus, to ensure high environmental criteria in the construction of the plant. They included replanting an area of almost 5.4 thousand square yards around the plant, water deposits for fires, drinking troughs for birds and other such details."

Solarpark Waldpolenz
Brandis, Germany

February 23, 2007

"Construction on a 40 megawatt (MW) solar generation power plant is under way at a former military base in the Saxon region of Germany. The total surface area of the planned photovoltaic (PV) installation? It’s comparable to about 200 soccer fields, said Matthias Willenbacher, cofounder and CEO of the juwi group.

The “Waldpolenz” solar park -- which is being developed by the juwi group in the township of Brandis -- will be comprised of approximately 550,000 First Solar thin-film modules. The direct current produced in the solar modules will be converted into alternating current and fed completely into the power grid.

Once completed in 2009, the project will be one of the largest photovoltaic projects ever constructed. Currently the biggest PV plant in the world has an output capacity of around 12 megawatts."

With a specific price of approximately Euro 3,250 per kilowatt [U.S. $4,226], the power plant is expected to be around 20%-40% cheaper than the going German market price. In addition, after just a year in operation, the “Waldpolenz” will have produced the energy needed to build it.

Stirling Energy and SoCal Edison
Mojave Desert : Victorville, CA

February 2, 2008

Stirling Energy is a United States company which develops equipment for utility-scale renewable energy power plants and distributed electrical generating systems. In California’s Mojave Desert, already home to 354 megawatts of SEGS solar thermal facilities, Stirling Energy Systems in conjunction with utility company Southern California Edison is erecting a 500 megawatt, 4,600-acre (19 km²), solar power plant to open in 2009. [1]

According to their website, Stirling Energy Systems (SES) is a systems integration and project management company that is developing equipment for utility-scale renewable energy power plants and distributed electric generating systems (“gensets”). Stirling Energy stands to rake in upwards of $90 million a year once the solar dishes are generating 500 MW in 2011. For SCE, already the largest purchaser of renewable energy in the U.S., the extra 500 MW will more than double the 354 MW of solar power it tapped in 2004 from nine other solar-thermal operations in the Mojave. It will also add almost 20% to SCE’s 2,588 MW of renewable energy sources, including 1,021 MW of wind power. Last year more than 18% of the electricity that the utility delivered to its customers came from renewables.

China’s Solar Projected Future
Dunhuang, China

November 20, 2006

In the latest sign that solar projects are growing larger, China announced plans Tuesday to build the world’s largest solar power plant in Dunhuang, a city in the northwestern Gansu province.

The plant, which will take five years to build, will yield 100 megawatts of peak capacity and will cost an estimated 6.03 billion yuan (about $766 million), according to the state-run Xinhua news agency.

That’s small compared to conventional coal-fired plants, which generally have capacities in the “hundreds of megawatts, if not a thousand megawatts,” said Joel Serface, director of the Austin Clean Energy Incubator.

But it’s large for solar, and it’s only one of several projects claiming to become “the world’s largest,” rapidly growing the world’s solar energy capacity.

Still, the latest announcement is significant news because China could potentially become one of the “world’s largest markets” for solar power, said David Saltman, chief executive of solar company Open Energy.


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