MINNEAPOLIS (AP) -- Minnesota regulators admit mishandling an investigation into a troubled electrical contractor, leading former customers to think they could've avoided financial losses.

State officials say they could've penalized M8 Electric Solutions and owner Michael J. Harvey for multiple violations if officials hadn't misplaced the investigative file for more than a year. Records show the state took no action against the company's unlicensed activity and shoddy work.

The state Department of Labor and Industry is now working to revoke licenses for Harvey and his new company, Able Energy, after receiving dozens of complaints from customers who've spent thousands of dollars on solar systems not yet installed.

Able Energy has collected around $1 million in upfront deposits without completing work on about 120 systems in Minnesota and Wisconsin.