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Now Solar Power To Meet Evening Peak Load In Hawaii

“Hawaii is a postcard from the future,” says Adam Browning, executive director of Vote Solar, a policy and advocacy group based in California. Driven by high electricity prices (highest retail electricity prices in the United States) the state has made an impressive foray into renewables.

Now, Kauai Island Utility Cooperative (KIUC) which supplies electricity to Kauai, the fourth largest of thesolar impulse main islands in the Hawaiian archipelago, has decided to “step up the gas” on solar to meet its evening load. In 2016, KIUC will develop a 17 MW solar PV power plant spread over an area of 50 acres. To be built by SolarCity, the package will come with a 52 MWh battery energy storage system. KIUC has signed a PPA with SolarCity to buy power from the project for 20 years.

The 52 MWh battery system will feed up to 13 MW of electricity onto the grid to reduce the evening peak, which lasts from 5 PM to 10 PM.

As of August this year, KIUC had nearly 40 MW of solar and about 3,000 customers with rooftop PV systems on its grid. The utility has the equivalent of five solar panels per customer on its grid, and at present, as much as 95% of daytime demand on Kauai is met by solar (rooftop installations + utility solar) but KIUC is keen to extend that further.

Under the power purchase agreement with SolarCity, KIUC will buy power at $0.145/kWh. To put this into perspective, the net cost of electricity from the year old 12 MW solar plant at Koloa (has small storage to balance grid) is about $0.11/kWh. The average cost of electricity from oil based power in 2014 was $0.22/kWh.

David Bissell, President and CEO of KIUC in a press release said that “KIUC has been investigating energy storage options for more than two years and price has always been the biggest challenge”.

To qualify for federal investment tax credits, which can substantially reduce the cost of the project, construction work must begin by April 2016 so that the project can start commercial operation by December 31, 2016. KIUC has requested an accelerated timetable for approval by the Hawaii Public Utilities Commission.

The utility-scale solar plant with battery storage will help Kauai avoid some of the problems that the neighbouring island of Oahu has experienced due to the surge in rooftop solar deployment. To add to the woes of the utilities managing the island grids, these isolated grid systems are more sensitive to variations due to cloud cover and there are no options to pass on these externalities (or import power from somewhere else). But thanks to its size, the battery storage system in Kauai can go beyond smoothing out grid fluctuations and actually meet demand.

At the moment, KIUC has three large solar PV plants — 12 MW each at Anahola and Koloa, and a 6 MW plant at Port Allen. Two smaller systems, a 1MW system in Kapaa and a 300 kW installation in Omao, also feed into the grid. But even with the previously installed systems, KIUC has had experience in utilizing grid-scale energy storage. Battery energy storage systems were integrated at the Koloa plant and at Port Allen to smoothen out the fluctuations generated by solar projects and stabilize the grid. The lead acid based battery system at Port Allen, however, could not handle the cycling and is said to have lost a large part of its storage capacity. The Anahola solar project is said to rely on a 4.63 MWh Lithium-ion battery storage is expected to handle this better. As per the supplier, SAFT, lithium-ion batteries are rated for four to six times as many full charge-discharge cycles as the lead acid ones. The battery technology for the proposed 17 MW system is yet to be announced.

The larger solar revolution, however, is on the other side of the grid. Recently, the stability of Oahu’s distribution grid has been challenged by solar, as 13% of its residents have installed PV systems on their homes. The Hawaii Electric Company has had to issue several precautionary measures to deal with over-voltage and power backflow, and requires a technical review for any system that lies on a region with a high percentage of distributed generation.

Miffed by the utilities, individual rooftop owners have now taken to solar and battery storage systems, choosing not to wait for grid connection clearances. Installers like SolarCity have been quick to jump at this opportunity. SolarCity’s CEO told the CFC Forum earlier this year that his main goal for 2015 is to “do a partnership with the utilities.” The company predicts that with expected declines in manufacturing costs, within a period of 5-10 years it will be economical for it to deploy a battery system by default with every solar PV system that it installs.

Follow the link for more stories from Hawaii.

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Written By

is a Fellow with The Energy and Resources Institute (TERI, New Delhi). He tweets at @indiasolarpost. Views and opinion if any, are his own.


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