Lines company Eastland Group is considering following the example of the Hawke's Bay lines company Unison and imposing an extra lines charge on people using solar panels.
But a final decision has not been made and can not happen for another year.
Two weeks ago, Unison put an extra tariff on people installing solar panels to offset its losses from getting lower lines payments from these households.
It said the cost of maintaining the line remained the same and without an extra charge, people without solar panels would subsidise those who have them.
Eastland chief executive Matt Todd said the charges for the current year had already been set, so no increase could happen for another twelve months. But after that, things could change.
"We don't want people who can afford to put solar on the roofs of their houses to be getting a subsidy from those that do not have solar," Mr Todd said.
The electric lines industry has said many times that people using solar panels and batteries pay lower power bills, making less money available to pay for the electricity grid.
Yet most solar panel users still need that grid to be available as a fallback when solar power dries up overnight or on cloudy days.
This problem is being looked at by the Electricity Authority, and for months no one made any moves, pending the authority's verdict.
But Unison took action three weeks ago anyway, saying it cost about $900 a year to provide a line to a residential customer and customers putting solar panels on their roof would reduce their contribution by $300, leaving a shortfall that would have to be made up by other people.
Unison said changing the rules brought fairness for its 110,000 consumers.
Critics including Greenpeace said Unison was doing the wrong thing.
So did the Sustainable Electricity Association of New Zealand, which called it a solar tax.
Unison said that was not correct and people installing solar would still save money on their power bills.
Eastland meanwhile said it was working on the programme but will not do anything until after the Electricity Authority had concluded its study.
"We hope to get some guidance from the Electricity Authority," Mr Todd said.
"Either way, this will be something we can reconsider as we move into the next pricing round, which would become effective from 1 April 2017."
There are 28 lines companies in New Zealand all facing falling revenue and static fixed costs.