NextEra Energy Inc.’s assertion last week that its proposed purchase of Hawaii’s largest electric utility would bring $1 billion in customer savings and economic benefits — up from its previously estimated $60 million — needs careful examination, and healthy skepticism.

The super-sized statement came just a day after state Consumer Advocate Jeffrey Ono called NextEra’s proposed $4.3 billion purchase of Hawaiian Electric Industries “flawed” and not in the public’s best interest.

On Monday, Ono said Florida-based NextEra has not clearly laid out how its purchase will result in significant benefits for consumers, which at the time of his analysis, was $60 million over four years.

In his 548-page assessment and rejection of the deal, Ono said the company’s filings “do not clearly or consistently explain how these savings will materialize … for example, millions of dollars in purported savings resulting from broad reductions in operations and maintenance expenses that have not been clearly laid out.”

These were severe words from the consumer advocate, who also stated that NextEra and HEI must provide an updated economic impact analysis for at least five years following the transaction that includes planned changes in employment at the utilities.

In other words, it’s time for facts and figures, not just propaganda.

NextEra responded a day later by sweetening the pot to $1 billion over five years, but still failed to provide details.

It, and HEI, will have until Aug. 31 to file a rebuttal to the consumer advocate with the state Public Utilities Commission.

NextEra’s $1 billion customer benefit assertion provoked another critical blow later in the week — this one from Hawaii’s Sierra Club, which called on NextEra to withdraw its proposal, and questioned the credibility of the exponential increase in projected savings.

There is no doubt the proposed deal could be a game changer in a state that is burdened with the nation’s highest energy bills. But consumers should rightly question how the deal will affect their electricity bills for years to come — and demand detailed answers.

Last month, Gov. David Ige announced his opposition to the proposed deal, saying NextEra needs to show it aligns with state clean-energy goal of 100 percent renewable electric energy by 2045, which the company has described as aggressive.

Two other state agencies — the Office of Planning and the Department of Business, Economic Development and Tourism — also have concluded that answers provided to questions by intervenors in the case before the Public Utilities Commission were insufficient.

Following the consumer advocate’s announcement, a NextEra spokesman said the company will continue to listen and, at this stage in the PUC review process, is confident it will find more common ground.

“But what this story is really about is Hawaii’s future — a 100 percent renewable (electric) energy future … ” said NextEra spokesman Rob Gould in a written statement.

So far, NextEra’s comebacks attempt to sound the right notes, but lack the evidence to assure consumers.

With so much at stake for ratepayers and for Hawaii’s clean energy future, more clarity on purported savings is needed.

Otherwise, NextEra’s promises become increasingly hollow, with doubts growing with each hyperbolic assertion.