Data centers consume massive amounts of power, but they’ve also got wide expanses of flat rooftop that could be prime real estate for capturing solar energy. One data center has decided to put its 528,000-square-foot rooftop to work, installing a huge solar array that will produce three times as much renewable energy as the solar panels on the roof of Googleplex, which currently has the largest system of any data center in the U.S.

The Phoenix ONE Data Center will install the first phase of 5,000 solar panels later this year, to be operational by January. This phase will generate 500 kilowatt-peak (kWp), and will be expanded in four additional phases during 2010 to reach a total capacity of 4.5 megawatts-peak. The plant will save even more energy by operating its A/C chillers at night, when power is less expensive, and storing the energy in on-site thermal storage facility to provide cooling during the day.

But even this expansive solar array isn’t enough to completely power the data center. 4.5 megawatts is only about 6 percent of the 80 megawatts required to run the power-hungry facility. While many data centers use solar panels to provide a percentage of their power needs, only one is fully powered with solar energy – the 1,500-square-foot AISO facility in Romoland, Calif.

“If we can generate 3 megawatts during the day, combined with our thermal storage, we can shave our power costs by about 50 percent,” said George Slessman, the CEO of i/o Data Centers. “Anything I can do to move my power consumption to off-peak hours is going to save a lot of money. Solar is the renewable approach that works best during peak daytime power pricing.”