Arizona Public Service recently unveiled an agreement with First Solar for a utility scale solar-plus-storage project that is designed to shift solar power into the evening hours.
The 65 MW solar farm will be coupled with a 50 MW, 135 MWh battery array and located next to APS’ existing Redhawk gas-fired plant in western Maricopa County.
The new facility is expected online in 2021.
The First Solar project was chosen through a competitive solicitation that sought 400 MW to 700 MW of resources to serve the summer (June to September) evening peak from 3:00 pm to 8:00 pm.
As part of the same solicitation, APS also signed a tolling agreement with an existing natural gas-fired combined-cycle unit for the summers of 2020 through 2026 for a total of 570 MW.
The need for the evening peak power was identified in APS’ 2017 integrated resource plan.
The solar-battery project shows that in “certain instances” batteries can compete with conventional peaking resources, APS spokeswoman Annie DeGraw said.
Under the power purchase agreement signed with First Solar, APS will have full use of the electrical output from the batteries. “Solar is a fantastic resource and this project allows us to use it at its best at midday and shift it to get the most benefit,” DeGraw said.
The agreement also lets First Solar use any of the solar power beyond the 50 MW needed to charge the batteries.
“The project is primarily designed to charge the batteries, but we are looking at opportunities” to sell any solar power beyond the amount needed for charging, First Solar spokesman Steve Krum said.
First Solar, as the owner of the project, also has the rights to the investment tax credit for both the solar and storage portions of the project.
Last summer, APS announced plans to install a 2 MW, 8 MWh battery storage system in Punkin Center, Ariz., as an alternative to upgrading a distribution line to serve the remote community in the Tonto National Forest.
APS’ integrated resource plan calls for the utility to install more than 500 MW of battery storage over the next 15 years.
An Arizona utility regulator recently proposed to revamp the state’s power sector by requiring utilities to get at least 80 percent of their power from zero-carbon resources by 2050 while deploying 3,000 megawatts of energy storage by 2030.
The proposal by Arizona Corporation Commission member Andy Tobin calls for broadening the state’s renewable portfolio standard, which climbs to 15 percent by 2025 and would be renamed the Clean Resource Energy Standard and Tariff.