Energy Storage

SRP, NREL to study residential battery storage use

Arizona public power utility Salt River Project and the National Renewable Energy Laboratory are launching one of the largest ever studies of residential battery energy systems.

“With energy storage technologies gaining importance, this study is a landmark effort to understand the value that [battery energy system] technologies will have to both customers and utilities,” NREL said late last month. “The breadth and resolution of data, combined with the modeling and scenario analysis performed by NREL, will constitute a critical look at the foreseeable impacts of the storage industry.”

The study will be based on a new SRP program that provides $150 per DC-kilowatt-hour, or up to $1,800, for 4,500 residential customers who install qualifying lithium ion battery systems. SRP expects about 275 customers will participate in the study, according to SRP spokesperson Patty Garcia-Likens.

Effective battery systems can store solar energy generated during the day to be used in the evening and night, potentially allowing homeowners to use more of their rooftop solar system’s output, SRP notes.

The program will be available for three years starting May 1, 2018.

NREL in late October said it would help SRP during the three-year program by evaluating battery technologies and interpreting data about how customers are using their battery systems.

The study’s first phase will use research capabilities only found at NREL, including the Energy Systems Integration Facility’s high-performance computing to manage the millisecond-to-minute resolution data, and advanced battery testing in NREL’s thermal testing facility, according to the Energy Department’s research lab.

Later study phases might use data from customer battery use and battery energy system performance, allowing NREL researchers to develop modeling and simulation tools to assess how battery systems benefit customers and affect the distribution grid, according to the research lab.

Because of the study’s length, SRP and NREL will be able to see the effects of several weather cycles, Garcia-Likens said.

While still small, the battery storage market has been growing quickly. About 62 MW of storage was deployed in the second quarter this year, up 60 percent from the same period last year, according to a September report from the Energy Storage Association and Wood Mackenzie Power & Renewables. In the same period,157 megawatt-hours of energy storage was deployed, three times more than in the second quarter of 2017, the report said.

Residential deployments were concentrated in California and Hawaii, which together account for 72 percent of the MWh in the quarter, the report said.

Wood Mackenzie expects annual deployments to grow from about 774 MWh this year to more than 11,700 MWh in 2023.

In the near term, cost declines of lithium ion batteries is slowing, according to the report. Average prices fell 20 percent a year in 2015 and 2016 and 15 percent last year, the report said. The pace of price declines slowed sharply in the second quarter to about $225/kWh.

There is a shortage of battery cells, especially of nickel-manganese cobalt oxide batteries that are being used in electric vehicles and stationary energy storage systems, according to the report. The trade group and Wood Mackenzie expect the prices for NMC batteries to start falling when production expands.

Storage installations will likely grow to about 3,900 MW a year in 2023, up from close to 400 MW this year, according to the ESA and Wood Mackenzie forecast.

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