Tesla has deployed a large new Powerpack system in Nantucket, which relies on two underwater cables, to secure the island’s power.

Nantucket is a small island of about 11,000 permanent residents about 30 miles off the Massachusetts coast, but it’s also a very popular tourist destination.

During the summer, the population can rise to 50,000 people, and the demand for power rises with it.

The island’s electricity is currently supplied via two submarine cables that connect to the mainland transmission system on Cape Cod.

It results in a critical failure point, but the island’s power is still secured with two six-megawatt diesel generators acting as backup power.

In 2017, National Grid, the power company in charge of the system, warned that the two generators are reaching the end of their useful life and need to be replaced.

Instead of going with new generators, the company commissioned Tesla to build a 6 MW/48 MWh battery energy storage system.

Two years later, the project is now completed, with 234 Tesla Powerpacks deployed on the island (via WBUR):

[National Grid] project manager [John] Skrzypczak says that BESS is made up of lithium-ion batteries — the same chemistry used in your cellphone. Think cellphone batteries the size of refrigerators. The 234 Tesla power packs are lined up in three long rows, storing backup electricity that can be fed onto Nantucket’s grid. If Nantucket goes flat or loses a cable, BESS would kick in before the diesel backup.

The project can power half the homes on the island for up to eight hours.

National Grid considered charging the Tesla batteries with a solar array, but there’s a space constraint.

Instead, they can charge it using the two underwater cables connected to the mainland grid or the diesel generators.

Tesla Energy

It’s not Tesla’s largest Powerpack project, but it is one of the biggest deployed to date when it comes to energy capacity.

Last quarter, Powerwall and Powerpack deployment grew by 81% in the second quarter to a record 415 MWh.

It’s unclear if this new project will count for the third or fourth quarter, but it should give a good boost to Tesla Energy.

To date, Tesla has now installed Powerwalls and Powerpacks at more than 50,000 sites around the world.

Earlier this year, Tesla also launched its new Megapack — a bigger energy storage product.

It will first be used at the upcoming Moss Landing project in California with PG&E. Over 400 Tesla Megapacks are expected to be used to create a massive energy storage system up to 1.2 GWh.

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