By Jason Deign
A solar-plus-battery project in Hawaii is showing how energy storage can help take the stress off the grid while delivering benefits to utility customers.
The system, at the University of the Nations on the island of Hawaii, is helping to provide backup power while at the same time saving the utility network from being overloaded with solar energy.
A key benefit for the university, though, is utility bill savings. It is expecting to save around USD$2.4m over the length of a 20-year power-purchase agreement (PPA).
Energy management systems company EnSync Energy Systems, of Milwaukee, USA, and its Pacific project development subsidiary, Holu Energy of Honolulu, unveiled the system in 2015.
The university decided to install the system, which comprises a 412kW PV plant and 320kWh of storage, to head off increasing electricity bills as it grew.
Generator for back-up power
It was also planning to buy a new generator, as part of a state requirement for back-up power on all buildings with more than seven stories.
With solar plus storage, the university avoided the running costs and carbon footprint associated with diesel generation.
The project was designed to connect to the grid under the grid-supply and self-supply interconnection options announced by the Hawaii Public Utility Commission to replace the state’s net energy metering programme.
“Considering the island’s electrical grid, Holu and EnSync designed a system that will help achieve a lower cost of energy, ensure electricity during outages and support grid stability,” said Ted Peck, Holu’s CEO, in a press release.
The building housing the system, which was engineered, designed and installed by Hawaii’s Kama’aina Solar Solutions, also contains the University’s cafeteria, a data centre, lifts and emergency shelter.
All these can now run without grid power thanks to the solar-plus-storage system.
Dan Nordloh, executive vice president at EnSync, told Energy Storage Report that the system uses EnSync’s Matrix Energy Management platform to integrate power from the grid and distributed energy resources (DER).
“We’re going to ensure that site gets the least expensive, most reliable electricity from all available energy sources,” he said. “That can be conventional grid utility, any DER, generation and-or storage.”
The platform also allows for application and revenue stacking on the storage asset, which in the University of the Nations’ case is a hybrid system combining EnSync Agile flow batteries and lithium-ion battery technology.
The project was slanted towards energy rather than power delivery, Nordloh said, and was backed by an unusual business model.
A portfolio of five projects
EnSync invested around $2.5m from balance sheet into the project. This formed part of portfolio of five projects, each with a long-term PPA, which was then sold to a third party.
The purchaser, American Electric Power, one of the largest investor-owned utilities in the US, kept EnSync on to provide operations and maintenance on the plant for the duration of the PPA.
The system has been running as planned, which is more than can be said of the grid supplies the plant is designed to supplement.
“The grid in Hawaii is not the most resilient of grids,” Nordloh commented. “We right-sized the solar in conjunction with the energy storage so we could time-shift over-production of solar into energy storage.
“We’re deploying that into the evening. That precludes them from having to use utility power during that time.”
Requirements to keep things cool
Furthermore, he said: “From a resilience perspective, they’ve got the right power and energy to serve near-time power requirements for elevator backup and energy requirements to keep things cool for a longer period of time.”
In theory, the University of the Nations system could also provide services to deliver greater value to the Hawaiian grid, for example by working alongside other storage systems as a virtual power plant.
In the meantime, the project has helped EnSync develop its own modelling capability, which now allows it to efficiently predict the value storage could have elsewhere.
EnSync now has around 20 solar-plus-storage systems installed in Hawaii, with a growing pipeline.
“Where our systems get most uptake, it’s where people are dealing with price and policy in resiliency situations or opportunities,” Nordloh said. “We do quite a bit of work in island regions.
“Hawaii has really started taking up the technology, to help people address the price issue while also ensuring they’ve got resiliency and backup power in a grid environment that can have some challenges.”
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