So, it was the weather that caused all those wild price spikes for Central Maine Power Co. customers? It was a cold snap that hit just about the same time that the company rolled out its new billing system?

That’s what the company has long claimed. And that’s what the Maine Public Utilities Commission staff reported last week, when it released its review of CMP’s data. It was the colder-than-typical winter of 2018 that drove up usage, and, along with a rate increase, led to higher bills, according to the PUC.

Uh-huh, OK.

But what about the people whose bills are sky-high now, during a stretch of perfect late-summer weather?

What about the people who got substantial bills for buildings that didn’t have electric service?

What about the Skowhegan ice cream shop owner who saw a sudden, dramatic increase in his electric bill, even though he doesn’t operate his business in the winter?

We’re not sold on the PUC staff’s findings, and neither is Maine Public Advocate Barry Hobbins. His office has worked with a consultant who has taken another approach to analyze the data, coming up with a very different picture.

Hobbins concludes that CMP’s billing system suffers from multiple defects that are contributing to the errors on customer bills. And he is presenting his findings to the three-member PUC as part of its ongoing probe of CMP.

The arrival of these two contradictory reports puts the commission in an awkward position. Thousands of customers who received inaccurate bills will be watching what the PUC does. It’s not just CMP that has its reputation on the line. Mainers want to know if they can trust this regulator to put the public interest ahead of the interests of a big business.

The trouble started in October 2017, when CMP introduced a new billing system, called SmartCare, just as a massive windstorm caused the largest power outage in the company’s history.

In December 2017, an 18 percent rate increase went into effect. Almost immediately, customers began complaining of billing irregularities. The PUC opened a probe in March 2018.

The company has consistently said that the rate increase, combined with a very cold winter, drove up usage, which drove up bills. Those factors were to blame, not problems with the billing system, according to CMP — a conclusion supported by two internal audits and one outside consultant.

But cold winter weather does not answer all the questions.

An investigation this summer by the Maine Sunday Telegram analyzed hundreds of pages of documents related to CMP’s rollout of the SmartCare system and concluded that the company mismanaged the implementation of the new system and misled the public. The stories also profiled a dozen customers whose lives were disrupted by inexplicably high bills. One family described how they stopped bathing at home and started taking showers at the local Boys & Girls Club, to avoid even higher electric bills.

Hobbins’ report will be an important rebuttal to the CMP-friendly findings of the consultant group and the PUC staff. The PUC should at least see that there are still questions that CMP cannot answer. That should stop the commissioners from settling this case quickly in the company’s favor.

The public advocate’s consultant cannot pinpoint a single cause of the problem, Hobbins said. But its research has found ample evidence that the billing errors persist, and that they can’t be explained by a stretch of bad weather.

Until those answers emerge, the PUC should keep digging.