Arizona solar customers gain more time to lock in power credits

The Arizona Corporation Commission on Tuesday amended a recent decision to end retail net metering for customers adding rooftop solar, giving customers more time to install systems under the current rules.

Under the amended order, customers will be eligible for the current, retail net-metering rates for 20 years if they file an application to interconnect their rooftop solar system before their utility’s new rates take effect.

The Dec. 21 decision had based the grandfathering of rooftop solar customers on when their systems are actually interconnected with the utility grid. Solar customers already connected to the grid will continue to benefit from retail net metering and need do nothing to continue that, though that benefit is now limited to 20 years from the date of their interconnection.

But shortly after the decision was filed, Arizona Public Service Co. and other parties to the case requested that the order be corrected to allow grandfathering from the date each customer files an application for interconnection.

APS, Tucson Electric Power Co. and consumer and solar industry advocates said that using the date of interconnection as a cutoff for grandfathering under net metering would create major problems because customers have no control over when their systems are interconnected once they file an application.

Most major parties to the case had supported grandfathering net metering based on when a customer applied for interconnection. Some said inclusion of the offending grandfathering language appeared to be an oversight as a proposed order was substantially amended during two days of open-meeting debate.

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The administrative law judge in the solar case also supported the amendment.

All major parties to the case supported Tuesday’s decision, which passed on a 4-0 vote, with Commissioner Bob Burns out on an excused absence.

Arizona net-metering rules in place since 2008 require customers with grid-tied rooftop solar installations to be credited for excess power production at each utility’s retail rate.

But the Corporation Commission’s vote in late December scraps the system of net metering and replaces it with a new “solar export rate,” based on a proxy rate for power from utility-scale solar farms or on cost studies for each utility.

The solar export rates — expected to be a fraction of retail rates — will eventually be set as part of pending rate cases filed by utilities, including Tucson Electric Power Co. and Arizona Public Service Co.