Tesla Motors Inc. launched a solar project in Hawaii, in association with Kauai Island Utility Cooperative. Tesla will provide solar power using its panels and battery packs at a solar farm with 13 megawatts (MW) of generating capacity.

The solar farm is made up of nearly 55,000 solar panels and includes 272 Tesla Powerpack lithium-ion batteries with a capacity of 52 megawatt-hours.

Tesla Li-ion batteries will help a Hawaii utility boost its use of solar energy.Tesla Li-ion batteries will help a Hawaii utility boost its use of solar energy.KIUC’s Strategic Plan 2008-2023 initially set a goal of reaching 50% renewable by 2023. The utility in February said it expects to reach that goal in 2018, five years early.

The Solar City/Tesla solar-plus-battery facility means that the utility has achieved roughly 44% renewable generation, said KIUC’s President and CEO, David Bissell. “This is truly remarkable when you consider that as recently as 2011 we were 92% dependent on fossil fuel generation.”

In September 2015, KIUC signed a power purchase agreement with SolarCity to supply power to the grid in the evening, when demand is highest. The 52 MWh battery system will feed up to 13 MW of electricity onto the grid to shave the amount of conventional power generation needed to meet the evening peak, which lasts from 5 p.m. to 10 p.m.

Under terms of the deal with Tesla, KIUC will buy power for 20 years at the rate of 13.9 cents per kilowatt-hour. The cost is reported to be lower than that incurred to buy power from diesel-fueled power plants and below the charge paid by consumers for electricity in the state.

KIUC also signed a contract with a unit of AES Corp. to develop a solar-plus-battery storage project on the island’s south shore. The project will include a 28 MW solar farm and a 20 MW five-hour-duration energy storage system, one of the largest battery systems globally.

Kauai Island Utility Cooperative is Hawaii’s only member-owned electric utility. At the end of 2016, 36% of the electricity generated on Kauai originates from a mix of renewable resources: solar, hydropower and biomass. That is up from 5% in 2009.

On the sunniest days, 90% of Kauai’s daytime energy needs are met by renewables - primarily solar - which is believed to be among the highest percentages of solar on an electrical grid of any utility in the U.S.

Among the utility's renewable energy assets are these:


Koloa array: This 12 MW project is owned by KIUC and went online in August 2014. The $40 million array is capable to producing nearly 6% of Kauai’s energy needs and reduces KIUC’s oil consumption by 1.7 million gallons a year.

Anahola array: The largest solar project in the state, this 12 MW, $54-million solar array came online in October 2015. The array consists of 59,000 panels.

Customer solar: Up from 311 systems in 2010 to 3,100 as of October 2015, rooftop systems are now used by 10% of residential customers.


Green Energy: This 7 MW plant is capable of providing 12% of Kauai’s power. The $90-million project burns wood chips from invasive species and from locally grown trees.


Five hydroelectric plants, some built more than 100 years ago to provide power to sugar plantations, are capable of generating 7.5% of Kauai’s electricity. A 6 MW project is in the permitting process and is expected to come online by 2019. It would be the first new hydroelectric plant on Kauai in 80 years.

Energy storage

Batteries: Prior to the Tesla project, KIUC had 10.5 MW of battery energy storage on its grid. This includes 6 MW of storage with a lithium-ion battery system at the Anahola solar array.

Pumped storage hydro: The system proposed for Kauai’s west side will use an upper storage pond connected by a five-mile-long buried steel pipeline to a lower pond. During the day, solar power would be used to push the water uphill to the storage pond. At night, when demand for electricity is at its peak, the water would be released, flowing downhill through the pipe to turn a turbine and generate electricity.

Smart grid

KIUC deployed 28,000 smart meters in 2013, enabling customers to go online to track their own energy use and set goals for efficiency. The technology will also enable KIUC to experiment time-of-use rates, pre-pay billing, and offer other service enhancements, including outage maps.