PORTLAND, Maine (AP) The staff of the Public Utilities Commission says high power bills that sparked outrage and a class-action lawsuit were caused by high usage during cold weather, not problems with Central Maine Power’s billing system or electric meters.

The finding tracks with an independent audit that blamed frigid temperatures, combined with a modest rate increase, for overbilling complaints.

A spokeswoman said CMP is pleased with the conclusion that it “accurately collects and tracks customer energy usage from the meter to the bill.” CMP acknowledged that more than 97,000 customers received bills in 2017-2018 that were at least 50 percent higher than a year earlier.

The Portland Press Herald reports the PUC staff still has to make a formal recommendation; the three-member panel is expected to vote on Dec. 20.