The world’s largest installed photovoltaic (PV) farms are powering tens of thousands of homes—mostly in Spain and Germany. The increase in the speed of installation and the size of PV installations is astounding. The largest PV installation just three years ago was about 20 megawatts (MW); today’s largest PV plant is three times bigger. And PV plants now being built in the United States and around the world—including Southern California Edison’s 250 MW warehouse farm—will dwarf today’s operating PV power plants.

The United States isn’t even in the top 10 as of this writing. The largest PV plant in the United States is 25 MW, the DeSoto Next Generation Solar Energy Center in Arcadia, Florida, and it’s the fourteenth largest PV plant in the world. It powers about 3,000 Florida homes in DeSoto County. However, that may soon change. Energy Farm Inc. plans to build a 75 MW PV plant in Florida. That project is expected to cost about $300 million.

1. Update: as of October 2010, the world's largest photovoltaic plant is the Sarnia, Ontario PV plant in Canada. Previously, the world's largest operating photovoltaic installation was the Parque Fotovoltaico Olmedilla de Alarcón, a 60 MW plant in Olmedilla, Spain. The farm produces enough electricity to power 40,000 homes in Spain—that’s equivalent to about 87.5 gigawatt hours a year. The plant has 270,000 photovoltaic modules, was built over a 16 month period, and completed in 2008. The plant cost 384 million euros to build.

2. The folks in Straßkirchen (yeah, I don’t how how to pronounce ‘ß’ either), enjoy getting their power from the 54 MW Strasskirchen Solar Park. The PV plant is capable of producing power for roughly 15,000 homes in Germany. The farm covers 135 hectares of land with about 225,000 solar modules. Construction was completed in less than six months, according to Q-Cells. The PV park reduces carbon dioxide emissions by 35,000 tons annually.

3. Solarpark Lieberose, another German solar plant, is just 1 MW shy of rivaling the Strasskirchen plant. The farm has 53 MV of First Solar thin-film PV panels installed. The plant powers about 15,000 homes. Juwi built the Lieberose PV plant on 162 hectares of former German military training grounds. As part of the initial agreement, Juwi agreed to pay to remove all munitions leftover from the 300 hectares it’s leasing from the German state of Brandenberg. Juwi has a 20 year lease for the land. After the lease is up, the solar park is set for dismantling, and the land will be used for pasture. About 160 million euros were invested in the project.

4. Spain comes in again in the top 10 with the 47.6 MW photovoltaic farm, Parque Fotovoltaico Puertollano. To maximize sunlight hitting the 231,653 fixed panels made by Suntech and Solaria, they are oriented at a 33 degree angle and face south.
5. Moura, Portugal jumps into the top five largest power plants, with its 46 MW Moura Photovoltaic Power Plant. Acconia, which developed the power plant, considered it part of a larger 115 MW power plant, which includes 66.8 MW of PV installed in solar gardens in Spain. Moura may become the world’s largest solar plant by the end of 2010, when 20 more MWs of photovoltaics are installed in its second stage.

6. The 45 MW Köthen photovoltaic power plant, was completed at the end of 2009, within four months of its groundbreaking in August 2009. RGE Energy AG, which owns the project, agreed to build the plant on top of a former military airfield. It has 205,000 photovoltaic panels. RGE said it’s enough to power Köthen's complete population, about 9,400 homes, and added that the plant will abate 25,000 tons of CO2 emissions annually.

7. Q-Cell SE, which installed the Strasskirchen Solar Park also installed the Finsterwalde Solarpark in Germany. It’s a 42 MW solar farm completed in Autumn 2009.

8. Eastern Germany’s 40 MW Waldpolenz Solarpark is a thin-film photovoltaic plant, built by Juwi with First Solar thin-film panels. It powers about 10,000 homes in the region. It also abates about 25,000 tons of carbon dioxide that would be produced by coal power plants annually.

9. Planta Solar La Magascona & La Magasquila in Trujillo, Spain, completed in 2008, produces 34.5 MW of photovoltaic power.

10. An installation in Arnedo, Spain, rounds out the top 10 with the 34 MW at the Planta Solar Arnedo. The plant also was completed in 2008.