A technician installs solar panels on the roof of a Tucson Electric Power customer.

Mamta Popat / Arizona Daily Star 2016

The Arizona Corporation Commission will consider new rules on the value and cost of customer-owned solar systems starting Monday, in a process expected to have significant impact on the adoption of rooftop solar across Arizona.

The issue

Utilities including Tucson Electric Power Co. want to reduce the “net-metering” rate, at which they reimburse customers with rooftop solar for their excess power generation, contending that solar customers aren’t paying their fair share of fixed grid costs.

Solar companies and advocacy groups counter that solar is worth far more than the utilities say in terms of reduced costs and pollution, and that any cuts to net-metering rates would devastate the industry.

What’s happening

The Corporation Commission is expected to issue a decision directing how rooftop solar will be valued for purposes of setting net-metering credit rates, including proposals to base new rates on studies of costs avoided by rooftop solar, or the price of power from large, utility-scale solar farms.

Ultimately, the commission’s solar valuation ruling will be used in pending rate cases filed by TEP, Arizona Public Service Co. and other utilities. The new rules are not expected to affect customers with existing rooftop solar systems.

Interest high

A coalition of 37 Arizona community, environmental, and public health groups recently sent a letter urging regulators to consider the long-term value of solar, and several Tucson groups are planning to send a busload of supporters to Monday’s commission meeting.

Hundreds of consumers already have filed comments in the solar case, which was started in January 2014 and was the subject of weeks of hearings last summer.