The California Supreme Court heard arguments in early June in a case that could be pivotal to the spread of rooftop solar panels in California.

Environmental and consumer advocacy groups are seeking to reverse a 2022 decision that changed the price major utilities pay for excess energy generated by customers with rooftop solar.

At issue is how much these customers are paid for the excess energy.

Prior versions of the program allowed customers to receive the retail rate for extra power, which is the price that electric companies charge other customers when they go on to sell it.

The current program instead gives customers the avoided cost which is how much the utility saved by not buying that energy somewhere else.

It's about 75% lower than retail.

Three environmental groups bringing the case argued that the California Public Utilities Commission didn't properly consider benefits to customers and disadvantaged communities when it changed the program.

The commission argued the policy strikes a balance between affordability for all customers and encouraging renewable energy choices.

The court's decision is expected within a month.

Under the program, which is called net metering, when customers install rooftop solar panels, they are typically guaranteed the rate they signed up under for about 20 years.

Outside of the Supreme Court case, a bill is seeking to change the program significantly.

Under the current program, should the solar user sell their home, the new owner would continue to receive the rate the previous homeowner signed up for.

If passed in its current form, the bill would stop this, preventing anyone who buys a home that's already part of the net metering program from keeping an older rate.

This is meant to help control costs, according to the text of the bill, but advocates say the move will harm rate payers.

For CalMatters, I'm Malena Carollo.