Kauai Island Utility Cooperative, whose grid has maxed out on the amount of solar it can take, has connected Tesla Powerpacks to get the island’s largest solar system online.

KIUC and Tesla representatives held a blessing ceremony Wednesday for a 13-megawatt solar system located on 50 acres of Grove Farm property north of Lihue. The system is connected to Tesla Powerpacks, which store enough power to service 4,500 homes during peak night demand. The solar farm has 50,000 solar panels.

In an interview Tuesday, KIUC Chief Executive Officer Dave Bissell said the utility had to connect batteries to the solar facility because Kauai’s grid has reached the maximum amount of PV it can take — 97 percent of daytime energy use on the island is supplied by renewables.

“It’s a big project for Kauai,” Bissell said. “It’s our first big battery and solar project.”

Tesla is contracted to sell the energy produced at the facility to KIUC for 13.9 cents a kilowatt-hour over the next 20 years.

“We had to keep investing in relatively cheap solar,” Bissell said. “We had to figure out a way to move it to nighttime. During the prime sunlight hours from 11 a.m. to 2 p.m. when the sun is its brightest, all of it is going into the battery. … Projects like this will become more and more routine on Kauai.”

The cooperative has another solar-plus-storage system on its way, as the utility signed a contract for one nearly twice the size of the Tesla facility earlier this year.

KIUC announced in January that it signed a contract with AES Distributed Energy Inc., a subsidiary of Arlington, Va.-based AES Corp., to build a 28-megawatt solar system connected to a 20-megawatt, five-hour-duration energy storage system. KIUC will buy energy from the solar system for 11 cents a kilowatt-hour. It is planned to be built on former sugar land between Lawai and Koloa on Kauai’s south shore.

Bissell said KIUC had been exploring battery technology for several years but the commercial batteries didn’t make financial sense until the cooperative signed the contract for the project with Tesla in November.

Bissell said the utility’s members will save money because Tesla’s batteries will send out 13 megawatts of energy over the four hours when costs are the highest.

“The energy we’re avoiding is the most expensive,” he said.

The new solar system will increase the island’s renewable energy dependence to 40 percent, up from 36 percent, Bissell said.

The cooperative’s board recently changed the island’s goal to have 70 percent renewable energy resource dependence by 2030 instead of the original benchmark of 50 percent — 10 years ahead of the state mandate.

“We’re about 50 percent with solar and biomass,” Bissell said.

The Tesla facility is estimated to reduce Kauai’s fossil fuel use by 1.6 million gallons of diesel annually.