Only 4% of the more than 900,000 smart meter customers are availing of the "time of use" feature, according to the ESB.

ESB's smart metering manager said the meters mean customers will not have estimated bills again.

Speaking on RTÉ's Morning Ireland, Carmel O'Connor added that time-of-use tariffs and energy insights also come into effect when a customer opts in to smart meters.

She said different time periods have different prices and a customer can see which appliances are using more electricity.

Ms O'Connor said the advice is to not use non-essential electrical goods between 5pm and 7pm, such as the tumble dryer, to save money as it will have the highest price tariffs.

She said the rollout is a phased approach as it is a major infrastructure over several years.

Ms O'Connor said that from November a large portion of customers will be able to log on to their account and check their usage on a customer portal and it will soon show real-time usage.

She said there is still work to do to get people to be aware of how smart meters work but more and more people are switching into opting into smart services.