Wisconsin Power & Light Co. raised electrical rates 1.58 percent after the Public Service Commission gave the subsidiary of the Madison-based utility Alliant Energy interim permission to raise the rate.
The increase is due to higher than expected fuel and purchased power costs.
"Fuel and purchased power costs have proven to be volatile in recent years," said Barbara Swan, WPL president, in a statement announcing the PSC decision. "WPL's ability to recover these prudent costs in a timely manner ensures fairness to customers and shareholders alike."
WPL serves about 400,000 electric and 175,000 natural gas customers, mostly retail.
Residential customers will see an average of 86 cents a month increase on the utility bill, but the impact on retail customers isn't known at this time.
The PSC will hold a public hearing on the final rate increase. If more money is collected by the utility under the interim increase than is expected under the final increase, customers will get a refund with interest.