Whoops!

Bowing to an outcry from customers, Apple (AAPL) reversed course Friday and said it would stay with a popular green product registry it withdrew from only two weeks ago.

In a letter to customers posted on the company website, Bob Mansfield, Apple senior vice president of hardware engineering, admitted it was a “mistake” to remove its products from EPEAT, a nonprofit rating group backed by many manufacturers and the U.S. Environmental Protection Agency.

The quick turnaround was a surprise to many. “The company has made very few missteps. This is clearly a misstep,” said Roger Kay, an analyst with Endpoint Technologies.

As of Friday, 40 Apple products, including the latest MacBook Pro, were on the group’s registry.

The announcement, which said the Cupertino company had heard from “many loyal Apple customers who were disappointed” by the decision to withdraw, didn’t explain why Apple pulled out of EPEAT in the first place. Apple has often touted its positive ratings from the group, and has in general received praise from environmental groups for its green efforts.

There had been speculation that it was tied to the design of the new MacBook Pros, which have batteries glued to the case and which might violate EPEAT’s standards for recycling. But Apple spokesman Steve Dowling said the batteries are removable using “common tools.”

In addition to triggering protests from customers, Apple’s decision meant that many cities and schools couldn’t buy Apple’s computers because they would not be on their lists of approved vendors.

One of the cities was San Francisco, but Melanie Nutter, director of the city and county Department of the Environment, said Friday, “It’s business as usual.”

Van Baker, an analyst with Gartner, said Apple clearly misjudged the reaction.

“Companies make mistakes,” Baker said. “They underestimate the reaction they’re going to get from the public, especially in an era of tweeting and social networks. The speed with which the news travels and the reaction to it is hugely accelerated. That’s what happened to Apple here.”

Endpoint’s Kay said it might have been a trial balloon by Apple to see if it could get away from an onerous standard.

“Within week or two if reaction is bad,” the company could fix it, he said. “In the end, Apple came out on right side of argument pretty quickly.”

Other computer manufacturers were undoubtedly watching the reaction closely, said Rob Enderle, a tech analyst with the Enderle Group in San Jose.

“It’s very expensive to maintain the certification, and there’s been a question about whether anybody cares, particularly on the consumer side,” Enderle said. “Apple suddenly discovered that people do care.”

In that sense, Apple “was the canary in the coal mine,” he said. “I think the entire industry was holding their breath on this one to see what would happen. I don’t think anyone else is going to do it now.”

The move to withdraw from the registry was even more curious because Apple has taken the lead in developing green products and worked to help develop the EPEAT ratings from its early days.

“They helped design many aspects of it,” said Sarah O’Brien, EPEAT’s communications director. “We’re happy to see them registering products” again, she added.

EPEAT’s CEO, Robert Frisbee, posted a letter on the nonprofit’s website confirming Apple’s return and saying it looks forward “to Apple’s strong and creative thoughts on ongoing standards development.”

In their letters, Mansfield and Frisbee agreed to work together to take into account rapidly evolving technologies.

“An interesting question for EPEAT is how to reward innovations that are not yet envisioned with standards that are fixed at a point in time,” Frisbee wrote. Ways to make that happen “are all on the table,” Frisbee wrote.

Mansfield noted that Apple “engineering teams have worked incredibly hard over the years to make our products even more environmentally friendly, and much of our progress has come in areas not yet measured by EPEAT.”

The company led the industry in removing toxins, and replacing plastics with recyclable, more durable materials, he wrote. Its batteries exceed Energy Star standards. he also noted.

EPEAT could be a better standard “if it were upgraded to include advancements like these,” Mansfield wrote.

Contact Pete Carey at 408-920-5419.