eBay has completed installation of a solar array on top of its LEED Gold-certified Topaz data center in South Jordan, Utah, the company says is its largest solar installation to date.

The array, designed and installed by SPG Solar, includes 72,000 sq ft of solar panels, covering virtually the facility’s entire roof, Richard Brewer-Hay, eBay’s senior manager for social media, wrote in a blog post.

“In addition to the environmental benefits, we anticipate the installation will pay for itself in just four years,” he wrote.

As an environmental benefit, eBay expects the array to offset 702 tons of greenhouse gas emissions. Its power capacity is 665kW and the company estimates it will produce more than 900,000kWh of electricity every year.

Together with the 650kW solar array and a 500kW fuel-cell installation at its California headquarters and its 100kW solar array at the Denver data center site, the new array brings eBay’s total renewable-energy-generation capacity to nearly 2MW, or 11% of the company’s total data center power demand.

Solar panels are considered an intermittent form of energy generation and their actual benefit, in comparison to a typical data center’s overall power requirements, is not clear-cut.

Just last month, Amazon Web Services’ James Hamilton questioned the value of Apple’s massive solar array at its data center site in Maiden, North Carolina. “I’ m personally not crazy about clearing 171 acres in order to supply only 4% of the power at this facility,” he wrote in his blog about Apple’s 20MW solar farm.

Hamilton estimated that the facility’s total power consumption could be as high as 78MW if it was moderately energy efficient.