Beyond being a titan of search, Google also has built one of the largest corporatesolarinstallations in the world.

In May, the company announced it had completed the bulk of a 1.6-megawatt solar project, with more than 9,000 solar panels installed throughout Google's Mountain View, Calif., campus.

But a look at the Google Web site tracking the project would suggest that the project isn't performing up to par. Earlier this month, Greentech Media readers pointed out the discrepancies between the expected electricity production and the site results.

"After observing and assessing hundreds of PV installations, I conclude a good [proportion] of all PV sites are not performing as they should," wrote one reader under the handle PROscyang who signed the comment as Steve. Pointing to the Google project, he added, "Its peak output yesterday appeared to be about 86 kilowatts, and energy produced was 296 kilowatt-hours. … The peak Googleplex composite output should have been in the 300-kilowatt range yesterday."

Another reader, writing under the name of Solarman, responded: "This system is rated at 1.2 megawatts, so at test conditions, it should produce 1.2 megawatt-hours of DC output power. If Google is producing only 86 kilowatt-hours at near-peak conditions, the system is clearly broken."

On Thursday, the site alternately listed the electricity produced in the last 24 hours as "0 kilowatt-hours" and as "169 kilowatts-hours."

But don't jump to conclusions. Google says the solar-power system is working fine. The solar panels have cut the Googleplex's grid energy consumption by 30 percent and will pay for themselves within seven years, the company said.

The problem, Google said, is the monitoring system.

"We're having some technical issues with the Web site whose program monitors our solar panels' output," said Robyn Beavers, head of Google's green business operations. The company is working to fix the program, which was built by an in-house Google engineer, she said.

Repairs include changing the monitoring system from a wireless to a wired one. Google gave no further details, other than to say that the monitoring system would be working again "soon."