Tesla is likely to deploy one of the biggest battery systems in the world with 244 Megapacks in Hawaii.

Tesla Megapack is a grid energy storage battery with a capacity of up to 3 megawatt hours designed for battery storage power station use, released in 2019. Each Megapack includes Lithium-ion batteries for energy storage, a circuit breaker panel, DC-to-DC converter units and thermal management, packaged together as a single unit inside a shipping container.

Groups of Megapack units working together are designed to operate like the "Tesla big battery" installed at the Hornsdale Power Reserve in Australia during 2017 using Tesla Powerpack units, and displacing fuel-based peaking power-generation facilities.

In December 2018, architectural plans for a site in California showed a proposed installation of several hundred Tesla Megapack containers for Pacific Gas and Electric Company (PG&E), near its Moss Landing Power Plant. The battery project was approved in 2020.

A 1.25 MW/2.5 MWh version was deployed in Canada in 2020.

Now, a similar project, called "Kahe Battery Energy Storage System", can become real in Hawaii. Hawaiian Electric, the largest local power plant serving 95 percent of the state, is developing a major energy storage project in the Kahu Valley, Oahu.

The aim of the project is to provide services of redistribution of load, and the creation of backup electricity for its electric network. Hawaiian Electric is considering offers from various companies, but at the moment Tesla is the leader.

Currently released Draft Environmental Assessment:

"Hawaiian Electric Company, Inc. proposes to construct and operate a Battery Energy Storage System (BESS) at its existing Kahe Generating Station, with interconnections to an existing substation at the station and the island-wide electrical grid. The anticipated total value of the Project is greater than $ 500,000."

The proposed project involves the construction, installation, and operation of a BESS, which will occupy roughly 5.9 acres, capable of dispatching up to 810 MWh of energy located on an undeveloped portion of Hawaiian Electric’s existing property at KGS. 

The project, which will be tied to Hawaiian Electric’s island-wide electrical grid, will provide the Company with the flexibility to incorporate additional sources of renewable electrical energy and reduce its overall use of fossil fuels on Oʻahu. All electrical components, including overcurrent protection, disconnecting means, surge suppression devices, conduit, wiring, and terminals, will have UL, IEEE, or equivalent listing and have appropriate voltage, current and temperature ratings for their intended use.

The project will include approximately 244 Tesla Megapack containerized grid energy storage batteries, each with an approximately 3 MWh capacity, designed for utility-scale power storage.

The equipment is packaged as a single unit in a shipping containertype housing referred to as the IP66 enclosure. Four Megapacks are grouped together. 

The Megapacks will be placed on poured concrete pads. The BESS modules will be divided into six distinct banks of (from northernmost to southernmost) of 52, 16, 44, 20, 72, and 40 units respectively, for a total of 244 Megapacks.

Each group of 4 Megapacks will be associated with a pad-mounted 2410/2700 kVA transformer for a total of 61 concrete-pad-mounted 505 Volt (V) to 34.5 kV step-up transformers. Each Megapack will be connected to its 2410/2700 kVA
transformer via underground conduit.

There is currently no final decision on this project, it is expected that this will be decided in May 2020. If the project is approved, then its construction will begin in the spring of 2021, in this situation Megapack will be launched in 2022.