Austin making the Lone Star state a test-bed for US solar storage
Austin in Texas is becoming a leading test-bed for developing solar storage systems. The city's public energy company Austin Energy has received the largest grant from the US federal government's dedicated fund for encouraging such technologies. The Department of Energy has established the Sustainable and Holistic Integration of Energy Storage and Solar (SHINES) initiative, which is spending $18m on six new integrated solar and storage projects across the US. Austin Energy has received more than $4m for its projects, which include residential, commercial and grid-scale storage facilities.

A battery storage project is planned for the Mueller neighbourhood, which hosts more than 250 rooftop solar installations. Image courtesy of Austin Energy.

Texas’s energy story may have been historically dominated by oil and gas, but that story is slowly beginning to change. The Lone Star State is inundated with renewable energy resources, with the largest wind and solar energy potential in the US. Indeed, Texas reached its 2025 Renewable Portfolio Standard goal of 10,000MW of new renewable energy capacity in 2010, 15 years early, and has consistently achieved green energy targets ahead of schedule ever since.

The vast majority of the state’s renewable energy success has been driven by wind power, in which Texas leads the nation with more than 20,000MW of installed wind capacity. Last year, wind accounted for more than 12% of Texan electricity production, powering the equivalent of 5.3 million homes.

Despite Texas’s size and the vastness of its solar resource (many cities in the state get a yearly average of 200 sunny days or more), solar power has lagged behind wind as a driver of its renewable energy growth. This can be partly explained by a less friendly business and legislative environment for solar in Texas, but also the discrepancy in end cost between solar and wind generation.

To help solar energy production catch up with its wind-based counterpart, efforts are ongoing in Texas to reduce the cost and improve the integration of solar power at the grid, commercial and residential scales. The key for solar as an intermittent energy source (like wind) is smart energy storage.

Austin SHINES

The key conundrum at the heart of greater renewables integration is grid reliability. Intermittent renewables such as photovoltaic (PV) solar panels need to find a prominent place in energy mixes to meet decarbonisation goals, but as these technologies achieve greater penetration, there are risks that uneven power generation patterns could hamper grid function and market stability.

The US is already investing in smarter grid technologies through its Grid Modernization Initiative, but other programmes are zeroing in on renewables and energy storage in particular. The Department of Energy’s (DoE) Sustainable and Holistic Integration of Energy Storage and Solar PV (SHINES) initiative is the first US federal effort specifically aimed at connecting renewables to storage technologies.

SHINES is funding the development and demonstration of integrated solar PV and energy storage systems that could better harmonise solar and reduce costs – the programme aims to move towards integrating solar plants with the grid at a system levelised cost of electricity (LCOE) of less than 14¢ per KWh.

In January 2016, the DoE announced $18m in federal funding for six new integrated PV and storage projects across the US. The largest slice of the grants went to Austin Energy – America’s eighth-largest public utility with nearly half a million customers in the city of Austin, Texas and the surrounding area – to help fund the Austin SHINES project.

This initiative is in the process of developing and deploying integrated solar and storage projects in the utility’s jurisdiction, concentrating on three major themes – storage and PV projects at the utility scale, the commercial scale and the residential scale – as well as looking into new models and software systems to help reduce customer costs and balance supply and demand for distributed energy resources (DER).

Ramping up solar storage concepts

The Austin SHINES project is scheduled to run up to April 2019; the design phase has now been nearly completed, with the deployment phase just beginning and the demonstration phase set to kick off in April 2018.

“We will begin to see the assets on the ground in various applications,” says Austin Energy utility strategist Cameron Freberg. “A lot of the design phase consisted of establishing partners, contracting, fine-tuning value streams and an immense amount of planning and collaboration.”

The $4.3m award from the DoE, as well as $1m contributed by the Texas Commission on Environmental Quality, has helped to accelerate Austin Energy’s plans for DER optimisation. A large number of partners have been sourced for the project, from state-wide grid operator ERCOT to energy storage integrator Doosan GridTech and renowned tech firm and storage innovator Tesla.

“The funding for the Austin Energy SHINES system includes pairing energy storage on the residential, commercial and grid-scale levels,” Freberg says. “One will be connected to a community solar farm in East Austin. The second battery storage project is proposed for the Mueller neighbourhood, an equally important opportunity since the neighbourhood has over 250 existing residences and businesses with rooftop solar, more than 60 electric vehicle owners, smart loads and appliances throughout homes and energy efficient design for all buildings. Residential and commercial properties will also have battery storage systems connected to their solar arrays as part of the SHINES project.”

At the utility scale, on-site grid energy storage at solar power plants can help stabilise power distribution networks when dealing with intermittent supply, storing electricity when it’s not needed and dispatching it at periods of peak demand or at times when solar is not producing.

As for residential and commercial users, distributed solar on residential rooftops or on business properties can provide value to customers while adding more flexibility by making power supply less of a one-way street. “Commercial sites will partner with Austin Energy and install battery storage systems,” says Freberg. “SHINES incorporates two use-cases, aggregated and direct utility control, for direct comparison and added flexibility. Residential customers will have battery systems deployed and integrated with rooftop PV as part of the SHINES project.”

Answering key questions

So what exactly are the technical, environmental and economic benefits of distributed solar energy storage expected to be? These are the questions that Austin SHINES intends to answer.

“Energy storage can provide a lot of value to the electric grid and to our customers whether it is through increased reliability, integrating renewables,” Freberg says. “Prioritising where value can be obtained and capturing this value are two of the major goals of the Austin SHINES project. Customer value and utility value are one, so whatever benefits we can provide to the utility are good for the customer, and vice versa.”

In April, Austin Energy brought intelligent energy storage specialist Stem onboard the SHINES project to offer an aggregated fleet of customer-sited energy storage for commercial users in and around Austin. Initially Stem’s tech will be used to test how quickly storage systems can respond to an aggregator’s signal to dispatch and provide grid response services, but over time the fleet is intended to demonstrate the benefits of intelligent storage distributed over many businesses, both to the utility and for the energy bills of commercial customers.

“Where a business has on-site solar PV systems, Stem’s software and analytics tools will automatically manage those customers’ use of grid-supplied electricity against their solar production,” Stem said in an April statement. “For all customers in the network, Stem’s proprietary software will rapidly respond to spikes in electricity use, drawing on stored power to automatically reduce demand charge costs without requiring operational changes or manual input from the host.”

Obviously there are many challenges to overcome to realise the full potential of energy storage. Upfront capital costs are high while various storage technologies continue to move towards maturity, and the wide array of storage systems being developed throws up issues around interoperability with existing utility infrastructure and grid management architecture in this increasingly multi-faceted market.

Austin Energy is hoping to answer many of these questions with its exploratory approach, and Freberg emphasises extensive collaboration, open standards and pairing storage closely with solar at the source to help ease these growing pains.

It’s clear that energy storage is becoming a lynchpin technology to accelerate the deployment of renewable power generation while preserving grid equilibrium and security of supply. Austin is set to become a true test best for energy storage, and if it can act as a showcase for the benefits, it could set the solar storage template for other states to follow, especially in the sun-drenched south-west of the US.

“Energy storage improves the way we generate, deliver, and consume electricity; it helps during emergencies like power outages from storms, equipment failures, accidents or other unforeseen circumstances,” says Freberg. “The game-changing nature of energy storage is its ability to balance power supply and demand instantaneously – within milliseconds – which makes power networks more resilient, efficient and cleaner than ever before.”