Xcel plan oversold in 2000; Investigation says wind overbilling went on for years.

Xcel Energy oversold wind energy credits as far back as 2000 for a program in which customers voluntarily pay a premium for wind-generated power, according to an investigation by Colorado Public Utilities Commission staff.

A settlement is looming related to Xcel's excess collections for the Windsource program from 2005 to 2007, which was disclosed earlier this week.

But the investigative report, completed in May and obtained by The Denver Post on Wednesday, reveals Xcel had overcollected years earlier.

The utility coined terms such as "carryover energy" to explain why it wasn't required to refund the 2000 overcollection even though it didn't generate enough green energy to meet the credits sold, the report states. Xcel argued that it had surplus wind energy from previous years that it "banked" and carried over to cover the overcollection.

"We note that the terms 'banking' and 'carryover energy' are nowhere mentioned in the stipulation establishing Windsource and appear contrary to the plain language of the agreement, which limits sales to the annual kilowatt hours produced," a PUC engineer wrote in the May report.

Xcel doesn't agree with the findings in the report, said spokesman Joe Fuentes. He didn't offer specifics, adding that the report was not to be released to the public.

PUC staff has not recommended that Xcel refund the 2000 overcharges but has said the utility should do so for excess fees collected from 2005 to 2007.

That amount has been pinned at $1.6 million, including interest. PUC documents show that Xcel is expected to overcollect at a greater rate in 2008 than it did in 2007, meaning that at least another $750,000 could be tacked onto the refund amount.

Xcel has said it should not have to refund the money because it generated or purchased more than enough wind power to cover the credits sold for those years. Some of that power, however, came as part of Xcel's efforts to meet state-mandated renewable-energy standards.

The Windsource program, and its generation sources, must remain separate from Xcel's other business operations under regulatory guidelines.

Despite that, Xcel has already included other renewable sources in the program's marketing, the PUC investigation found.

The deadline for a settlement, which stems from Xcel's filing in June to roll Windsource into the rest of its renewable portfolio, is Jan. 8.

Xcel sought regulatory approval for the program in 1996 to respond to growing customer demand for renewable energy. Regulators approved the program in 1997 with the stipulation that all risks would be assumed by Xcel shareholders.

The program launched in 1998 and has 46,800 subscribers, who pay about $10 more each month than typical customers. Windsource revenues since inception are estimated at nearly $38 million, with an estimated $18 million collected in 2007 and 2008, according to the PUC. Xcel has not added capacity to Windsource, which receives its power from two Colorado wind farms, since October 2001.

Denver resident Jeremy Swartz, a Windsource subscriber since 2006, is not ready to abandon the program but wants more transparency.

"Where is the money going?" he said Wednesday. "I don't want to pay for something if the power that I'm getting is not green energy."