The Indiana appeals court has ruled in favor of consumer advocacy groups that challenged a change in the way a southwestern Indiana utility bills customers who have solar panels.

The ruling reverses an order by the Indiana Utility Regulatory Commission that changed and reduced how CenterPoint would credit its solar customers, the Evansville Courier & Press reported.

Consumer advocates, including the state’s Office of Utility Consumer Counselor, had appealed the IURC's April 2021 order. Solar power proponents said the change would undercut the electric bill savings seen by homeowners and businesses that install solar power and would slow the growth of rooftop solar installations in Indiana.

The court's Jan. 28 ruling is a "big win" for CenterPoint's customers in southwestern Indiana, said Kerwin Olson, executive director of the nonprofit Citizens Action Coalition.

CenterPoint has 30 days to either ask for a rehearing by the appeals court or to petition the Indiana Supreme Court to take up the case.

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CenterPoint customers with solar panels are currently credited in a one-to-one exchange at the utility's retail rates through a process called net metering. Bills are determined based on the difference between the energy customers use and energy they export back to the power grid each monthly billing cycle.

For instance, a customer using 1,000 kilowatts of energy but sending 800 kilowatts back to the grid is billed for 200 kilowatts.

People walk past the solar panels at a wind and solar energy storage and transmission power station of State Grid Corporation of China, in Zhangjiakou of Hebei province, China, March 18, 2016. REUTERS/Jason Lee - RTSB3AZ

File photo - People walk past the solar panels at a wind and solar energy storage and transmission power station of State Grid Corporation of China, in Zhangjiakou of Hebei province, China, March 18, 2016. (REUTERS/Jason Lee)

Net metering is already being phased out in Indiana under a 2017 state law that changes how solar customers are billed to a smaller credit based on 125 percent of utilities’ wholesale rates.

Olson said that is about 70% to 80% lower than what customers receive at the current retail rates.

In its ruling, the appeals court said the state law still required that the billing to be calculated by the difference between power used and power returned to the grid.

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Olson said that because the ruling was a "decision of memorandum," it cannot be used as legal precedence in the cases involving Indiana's four other investor-owned utilities.

CenterPoint officials have contended that net metering is causing the majority of customers to subsidize customers who generate their own power, primarily through solar panels.

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In a statement Monday, the company said that: "CenterPoint Energy believes rightsizing the payment made to customers that return energy to the grid is important to ensure a balance between the interests of customers that own generation and those that do not."