The Michigan Court of Appeals says regulators wrongly approved a $37 million plan to help DTE Energy instantly track electricity consumption through so-called smart meters.

The court says the Michigan Public Service Commission didn't rely on "competent ... substantial evidence" to justify the rate increase in 2010. But the decision released Wednesday doesn't mean a rate reduction for customers. The commission will get another chance to look at the case.

The meters are high-tech devices that let DTE monitor electricity and gas consumption without sending a meter reader. Customers also can regularly monitor their energy use.

DTE Energy says 700,000 meters have been installed. The Public Service Commission is investigating the use of meters by utilities statewide. A staff report is due June 29.