Hawaiian Electric Co. is partnering with Elemental Excelerator and Enel X to study how electric vehicle charging during different times of the day affect the power grid.

Enel X, a global EV supply equipment company, is offering free smart chargers to the first 300 EV drivers, and first 50 businesses, who sign up for the “Smart Charge Hawaii Program.”

The JuiceBox chargers are being offered for free in exchange for participation, which involves the collection of usage data.

Hawaii was an ideal market for the program because of the high presence of renewables, and growing EV adoption rates, according to Enel X, which aims to measure as well as demonstrate smart grid EV charging benefits.

“With the highest rooftop solar penetration in the country, Hawaii is a fantastic match for our smart charging platform to dynamically balance electricity loads,” said Preston Roper, head of Enel X e-Mobility, North America, in a news release. “Through our partnership with Hawaiian Electric Companies and the Elemental Excelerator we are reinforcing the critical role that smart charging has towards scaling renewable energy in a sustainable and economical way.”

With the financial support of Honolulu-based startup accelerator Elemental Excelerator, Enel X’s smart charging stations will use JuiceNet software to track drivers’ historical charging patterns, and balance use with real-time input.

EVs are generally plugged in for longer than needed — overnight, for instance, rather than the four hours needed — to get a full charge from a level 2 charging station. JuiceNet automatically charges when the most renewable energy is available, typically in the middle of the day, rather than evenings, when overall consumption is high.

Users can override the charger, if needed, and charge immediately at any time via the JuiceNet mobile app or dashboard. As an incentive, participants who are flexible about their schedules earn JuicePoints, which are redeemable for cash.

As a group, Enel X says, all EV users plugged into JuiceNet can make a collective difference.

For HECO the program will help measure how much EV charging is done at home, and when, and how the equipment is used, as well as how users can be motivated to charge when it helps the grid the most.

Richard Barone, Hawaiian Electric director of demand response, said the company is on track to providing 30% renewables for customer use by 2020.

“So now is the perfect time to implement more smart charging as EV adoption and renewable generation grow in parallel,” said Barone in a news release. “This project will provide critical insights into how vehicle-grid integration can help us achieve our 100% Renewable Portfolio Standard goals efficiently.”

EV drivers and businesses that are customers of Hawaiian Electric, Maui Electric Co. and Hawaii Electric Light Co. can apply for the program online. Although the chargers are free, participants must pay for shipping and installation themselves, and must connect to the internet within 90 days or return them.