Flick Electric chief executive Steve O'Connor says customers could soon have "real certainty" over who is the cheapest electricity provider.

Comparing electricity providers could soon be faster and more accurate, as changes to the Electricity Code force greater transparency onto usage and billing.

From February 2016, retailers will have to provide almost all customers with smart meters - or nominated agents - usage data broken to half hourly slots for the previous two years.

The data will allow detailed analysis into exactly which tariff would be the cheapest for customers, rather than estimates provided by comparison websites.

David White Tim Rudkin, chief executive of Saveawatt says his company's service, Frank, could effectively allow customers to automate the task of changing power companies.

Current tariff comparisons are built mainly using monthly bills as well as questions about the number of people in a household and when they are home.

Although few customers are expected to make use of the data they can access personally, one company is already preparing a new switching service, while retailers can use information to pitch savings directly to potential customers.

Christchurch-based Saveawatt will offer a digital-based service, named Frank, which will allow users to enter their information once, and permit the service to determine who would offer them the best service.

Chief executive Tim Rudkin said users could simply get a text message informing them that they had change providers, without needing to deal with a single form or change their direct debits, once the service is set up.

Rudkin is already approaching retailers about cooperating with his company's service and believed electricity companies realised change was coming to the market.

"I think they're fully aware that digital disruption will come in some form or another...It's hitting industries globally. These guys are smart, they know their industry is not different to any other globally."

Saveawatt will not estimate how much the average user might save with its service, but Rudkin said the historical usage data would give much greater accuracy than existing comparisons.

"There's no assumptions. This is actually how much power you've used. It might mean you've got an incredibly efficient house or an inefficient one, but it's what goes through the meter."

Some retailers are welcoming improved transparency on comparison sites, believing they will benefit from greater accuracy over exactly who is cheapest.

Steve O'Connor, chief executive of independent retailer Flick Electric, which allows retail customers access to the wholesale price of electricity through the spot market, said the changes would lead to greater transparency over bills. Flick was likely to use access to the data as a sales tactic with potential changes.

"It enables us to give customers real certainty around what their savings would have been based on their exact usage, as opposed to an assumed profile, which is often what the market has been using."

Retailers and the Electricity Authority acknowledge that the current comparison services involve a number of questions and at times the need to answer the same question repeatedly.

"You've only got to not have one piece of information and some people cannot be bothered," Electricity Authority chief executive Carl Hansen said.

Whereas the Whatsmynumber? website, an initiative between the regulator and Consumer NZ provided "a pretty good approximation" through questions, Hansen said the half hourly data requirement would lead to much more accurate comparisons.

"It can be matched against the tariffs that are offered and there can be so much more precision and confidence about what is the best deal."

While the EA has already changed the Electricity Code to require usage data, it is in the process of deciding whether to go further, potentially compelling retailers to provide agents with base tariff data and access to the meter registry.

Hansen said some "large retailers" were raising concerns about being compelled to provide more information on the grounds that it might be private data of customers, but the EA did not believe there were any genuine privacy concerns.

"I don't see any particular downside" for consumers, Hansen said.