Electricity charges will soon depend on what time of the day you use power, the ESB has said.
Under a new 'time of use' tariff scheme, householders will be encouraged to use power at non-peak times to ease pressure on the national electricity grid.
The new system is expected to be introduced within the next two years.
"There will be time-of-use tariffs in the future," said Paul Mulvaney, the ESB's director of innovation. "It might be based on green energy periods.
"It will be part of a smart metering programme and residential customers can expect to see it in 2018 or 2019."
Mr Mulvaney did not say whether this meant tariffs would become more expensive during peak daytime hours or simply cheaper at night.
"The idea is that you encourage people to use less energy and greener energy and flex demand so as to be easiest on the system," he said.
"If you can get people to shift their load to night time, it's easier on the grid. We carried out trials and found that when people knew there were cheaper tariff periods, they saved 4pc to 5pc on their bills."
Mr Mulvaney was speaking as the ESB prepares to host a 'hackathon' in Dublin this weekend.
The event, to be held in CHQ's Dogpatch Labs from Friday to Sunday, will seek to reward the best new ideas on improving energy efficiency, electricity reliability and ecar management. Winners of the competition will win cash prizes of €5,000, €3,000 and €2,000 respectively.
The ESB will be providing anonymised data sets for each of the challenges to help people understand usage, customer profiles and trends in advance of the hackathon.
Mr Mulvaney said that the event was on course to attract more than 100 coders, entrepreneurs and start-up personnel to the event.
Applicants can enter on the website bigenergyhack.ie.
He also said the ESB would finally begin requiring payment for eCar charging points around the country.
Earlier this year, the utility postponed seeking €17 per month for usage of the almost 1,000 charging points nationwide.
However, Mr Mulvaney says the ESB is now communicating with eCar customers about the imminent introduction of charges. "We're currently looking at the appropriate tariffs," he said. "Ultimately, everything has to be paid for. We need to reinvest and keep the system up to date. We will have to charge."