Solar projects keep getting bigger, with a new "largest" installation announced nearly every month.

Abengoa Solar on Thursday said it would build the world’s largestsolarpower plant in Arizona. The concentrating solar-thermal plant will use mirrors to track the sun and heat a liquid, which will heat water to make steam, which will then be converted into electricity via turbines.

The plant is expected to have the capacity to produce 280 megawatts of electricity, enough to power about 70,000 homes, and to begin generating power for Arizona Public Service Co. in 2011.

That’s larger than the 64-megawatt Nevada Solar One project Acciona Energy completed in Nevada last year -- which then was touted as the world’s largest -- the 154-megawatt plant that Solar Systems and TRUenergy announced Monday, the 177-megawatt plant that Ausra is building in California or even the 250-megawatt plant that a consortium of southwestern utilities is developing in Arizona or Nevada. (Abengoa also is part of the southwestern consortium.)

But Abengoa’s 280-megawatt project might never actually be the world’s largest. Stirling Energy Systems announced in 2005 that it is building a 300-megawatt plant in California’s Imperial Valley for San Diego Gas & Electric, expected to be finished in 2010, and a 500-megawatt plant in the California part of the Mojave Desert for Southern California Edison, expected to be completed by 2012. Edison could choose to expand the latter project to as much as 850 megawatts.

And solar-thermal projects aren’t the only ones getting larger. Tucson, Ariz.-based Global Solar Energy, a company that makes strings of copper-indium-gallium-deselenide solar cells, which customers package into panels, plans to begin construction on a 750-kilowatt solar field March 6. The company said the field, expected to be completed this summer, will be one of the largest thin-film arrays in the United States.

The world’s largest thin-film solar park also is growing. Weighing in at more than 12.7 megawatts of annual production capacity, the Waldpolenz energy park in Brandis, in eastern Germany, already is the largest solar project in the country and the fourth-largest installation in the world (see a list of the world’s largest photovoltaic projects here). The Juwi Group plans to expand the capacity to 40 megawatts per year by the end of 2009 (see press release).

And as companies prepare for the possibility that competition will soon kick in, they also are packing on the pounds -- or rather, the production capacity -- to make themselves larger (and, theoretically, to lower their costs).

Schott, for instance, plans to break ground on its new solar-manufacturing plant Monday. The company, which announced it was building the facility to make solar-electric panels and concentrating solar-thermal receivers in January, said the 64-megawatt plant will provide jobs for approximately 350 employees initially, and grow to 1,500 employees when it’s fully built out.

Q-Cells last week said it would boost its solar-cell production by more than 300 megawatts with a new plant in Malaysia. The company produced 389.2 megawatts of cells in 2007, according to its fourth-quarter results.

And concentrating solar-thermal startup Ausra said last week it is in discussions for 1,000 megawatts of production and has another 6,000 megawatts "in the pipeline," according to CNET. The publication added that the company has raised $30 million in venture debt, is negotiating for $15 million more, and also hopes to raise between $100 million and $150 million in the third quarter of this year, close two project financings in 2009 and go public by 2010.

Part of the motivation to grow fast is to be the buyer, rather than the bought, in case of an industry consolidation (click here to continue to the next section).