"We're coming back with a different approach," Carlini said. "We'll still do an IT module, but now we'll have more modules on the electrical side."

Meanwhile other vendors have jumped in, including Sun Microsystems (now part of Oracle), Rackable Systems (now called SGI), IBM, Hewlett-Packard and Dell. Sales are still relatively low, however -- 60 containerized data centers were sold worldwide last year, Carlini said, citing a figure from IDC.

The volumes are small partly because not many companies buy that much equipment in one go. "How many companies need to deploy 2,500 servers all at once?" he asked. But the products are big-ticket items. HP's 20-foot POD, or Performance Optimized Data Center, this month, costs US$600,000 without the IT equipment inside.

Carlini didn't give specifics about the products APC will roll out but suggested it will offer several options, including "reference designs" that can be optimized around compute capacity, energy efficiency or cost. Like other companies, it will use standard racks that can hold IT gear from a mix of vendors.