The Tesla microgrid – American Samoa shows the way

Renewables based microgrids are a cost competitive option for energy supply islands and other remote locations.

Tesla and SolarCity have always been closely associated companies. With technological advances, particularly of energy storage with its complementary relationship to solar PV, their synergies have deepened. This has now culminated in the recently “overwhelmingly approved” acquisition – with more than 85% shareholder support –of SolarCity by Tesla. [Engerati-Tesla gets SolarCity]

CEO Elon Musk’s stated intention with the acquisition was to create the first “vertically integrated energy company offering end to end products”. The first ‘product’ out of the joint company, beyond the existing PV panels and battery storage units, is a solar tile based roof in several different design styles. [Engerati-The beautiful solar roof]

Next out – although developed while they were separate companies – is a microgrid solution, combining SolarCity’s PV panels and Tesla’s batteries. The project is being pioneered on the south Pacific island of Ta’u in American Samoa, located more than 6,400km from the west coast of the United States.

The Ta’u microgrid

The Ta’u microgrid, which was funded by the American Samoa Economic Development Authority, the Environmental Protection Agency and the Department of Interior, comprises 1.4MW of solar PV and 6MWh of battery storage from 60 Tesla Powerpack batteries.

Up to now the approximately 600 residents of Ta’u have relied on imported diesel for power, which is costly but also when supplies were running low has led to outages as the fuel was rationed to certain times of the day.

The microgrid can supply almost all the power needs of the island from renewable energy, continuing to supply power for up to 3 days on the very rare occasions of no sun.

“This project will help lessen the carbon footprint of the world,” says local resident Keith Ahsoon, who recalls a time when there was a 2-month gap when the boat with supplies including diesel was unable to reach the island. “Living on an island, you experience global warming firsthand. Beach erosions and other noticeable changes are a part of life here. It’s a serious problem, and this project will hopefully set a good example for everyone else to follow.”

The Ta’u microgrid is operated by American Samoa Power Authority, which provides power and other utility services across the islands. With a generator consumption of 1,300l of diesel per day, the microgrid is expected to offset the use of around 500,000l of diesel per year.

American Samoa, an unincorporated territory of the US, comprises five main islands with a total population of about 60,000. Ta’u is the largest of the Manu’a group, which also includes Ofu and Olosega. Under the 2013 Energy Action Plan, the goal was to achieve 100% renewable supply for this group by 2016.

According to a 2015 US DOE Energy Transition Initiative ‘snapshot’ on American Samoa, the renewable share of electricity was then about 1.6%. The largest facility is a 1.75MW ground mounted, grid connected PV system. Others include more than 700kW of rooftop PV on government and private buildings and a large solar water heating system at the LBJ Tropical Medical Centre on Tutuila, the largest island. Further solar arrays and the first wind turbines are under construction.

The microgrid opportunity

With its potential for other islands and remote locations, the microgrid opportunity is clearly another that Tesla intends to capitalize on. [Engerati-In Focus: Microgrids, Microgrids, Microgrids]

“Ta’u is not a postcard from the future, it’s a snapshot of what is possible right now,” writes SolarCity CTO Peter Rive in a blog posting on the project, which also solicits enquiries about microgrid opportunities.

Previous studies have indicated that mini- and microgrids have the potential to account for more than 40% of off-grid electricity requirements globally by 2030. [Engerati-Microgrids – Key For Electrification]

In practice the contribution may prove to be higher. In the latest ‘Poor people’s energy outlook 2016’, in 11 out of 12 community case studies investigated in three countries, Bangladesh, Kenya and Togo, decentralized mini-grids were found to be cost-competitive or cheaper than grid extension.

The fact that these decentralized systems would also provide more reliable power than grids currently can, and would be deployable in a fraction of the time, swings the balance further in their favour, states the report.

Purely solar-powered mini-grids were found to be significantly more expensive due to the high capital costs of storage and generation capacity needed to cover peak load. However, with the falling prices of solar PV and storage, and economies of scale created by national policy and programmes, hybrid and purely renewable mini-grids are expected to quickly become cost-competitive in a huge array of contexts.

The report concludes: “For most rural electrification, decentralized options are superior to the grid, and plans should reflect the need to balance mini-grids, stand-alone systems and grid extension to achieve universal access in a timely manner and at least cost.”

Further reading

Practical Action: Poor people’s energy outlook 2016

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