At least two of the world’s largest concentrating solar power (CSP) projects, in this case also known as solar thermal projects, are set to come online in August, according to recent reports. Both the Ivanpah Solar Electric Generating System (SEGS) in California and the Solana Generating Station in Arizona are set to start delivering power next month, which is a big milestone for CSP technologies in the U.S. and could help foster future generations of the technologies.

The two projects use different types of technologies. The Solana Generating Station by Abengoa Solar in Gila Bend, Ariz., is a 280 megawatt parabolic trough system that concentrates sunlight on liquid-filled tubes to power a steam generator and provide heat for thermal storage so the project can continue generating electricity into the evening and when clouds cover the sun. In all the project will have six hours of molten salt energy storage.

The BrightSource, NRG and Google Ivanpah SEGS being built by Bechtel is a 377 megawatt solar tower CSP system that consists of three tower systems. Whereas Solana looks like a giant silver farm with rows of reflective crops gathering sunlight, Ivanpah looks like a silvery flower, reflecting the sun’s light onto a receiving tower like a giant flower stamen. In the Ivanpah project the sunlight is focussed on the central tower where it is superheated into steam to use in a turbine system. The Ivanpah project will not have thermal storage.

Both the Ivanpah and Solana projects have been underway for years, since about the same time as some of the giant PV projects like First Solar’s 290 megawatt Agua Caliente solar farm in Yuma, County, Ariz. were getting underway. However, Agua Caliente was more than two-thirds complete last July and putting 200 megawatts of electricity online then. And while the PV projects have come online in blocks, these CSP projects are just now reaching completion and will come online largely all at once.

When the CSP projects were first proposed they also offered a better value per dollar than PV projects. However, since 2009 PV module production has skyrocketed, bringing the cost of PV down much more quickly than most had anticipated. Now it’s not clear which offers the better value proposition, but Ivanpah is anticipated to produce electricity at a levelized cost per kilowatt hour of 12 to 17 cents per kilowatt hour, according to the Department of Energy. And Solana is anticipated to produce electricity at about 14 cents per hour, according to Arizona Public Service (APS) in 2008. APS is purchasing the power produced at Solana under a power-purchase agreement. Ivanpah will provide electricity to Southern California Edison and Pacific Gas and Electric in California.

While it’s taken these behemoth CSP plants some time to get to fruition, now that they’re on the verge of commercial operation, it could help more see the potential of such generation systems as opposed to traditional central generation stations.