Rooftop solar

TEP proposed a new rate structure for solar customers.

Ron Medvescek / Arizona Daily Star

A standing-room only crowd is expected Monday in Tucson at a public comment hearing on Tucson Electric Power Co.’s treatment of customers who install rooftop solar arrays.

The session before an Arizona Corporation Commission hearing judge is set to start at 10 a.m. at the state office building at 400 W. Congress, room 222.

The public-comment session comes ahead of planned hearings in the second phase of TEP’s rate case, aimed at approving new rates for future rooftop solar customers. The proceeding also covers customers of UNS Electric, a TEP sister company that serves Santa Cruz and Mohave counties.

Formal hearings on the merits of TEP’s proposal originally were to start on Wednesday.

But the Corporation Commission administrative law judge hearing the case suspended that schedule in light of settlement negotiations between TEP, the commission staff and other parties that began in early June and continued last week.

TEP has proposed a new rate structure for customers who install rooftop solar in the future that would cut credits for excess solar production and mandate time-of-use rates with new monthly charges.

The first part of TEP’s rate case, addressing non-solar issues and decided by the Corporation Commission in February, resulted in an $8.50 increase to the average home customer’s monthly bill.

In its recent filing, TEP proposed a solar export rate of 9.7 cents per kilowatt-hour to reimburse future solar customers for excess energy production, compared with current reimbursement of about 11.5 cents.

Following a statewide policy adopted by the Corporation Commission in December, TEP’s proposed export rate is based on the average cost of power from utility-scale solar projects that TEP owns or from which the utility buys.

The proxy rate may be updated annually, and as part of TEP’s next general rate case it will be reset based on detailed cost studies.

TEP also proposed new grid-access and demand charges and a $4 meter-reading charge for solar customers. The changes would not affect TEP customers who already have installed rooftop solar.

TEP has proposed a similar rate structure for small-business customers that install solar, and it filed similar proposals for UNS Electric.

Supporters of rooftop solar have scheduled a rally opposing TEP’s proposal downtown on Monday before the public comment session begins.

Contact senior reporter David Wichner at or 573-4181. On Twitter: @dwichner

Senior reporter covering business and technology for the Arizona Daily Star/