The Green Party says its new energy policy could result in 30,000 homes generating solar electricity in its first three years of implementation, but the Government says it could push up power prices.
Under the Greens' new energy policy, the Crown would lend households up to $15,000 at low interest rates to help them install solar power systems.
The Greens want the Crown to lend money to households for the cost of installing photovoltaic systems at the same rate at which it borrows money - at present 4.1 percent.
At current prices, a typical $10,000, three-kilowatt system would produce $1000 worth of electricity a year, the party says, and paying off the debt would cost $900 a year.
Co-leader Russel Norman said the debt would be repaid through rates and be attached to the house rather than the occupants.
He said households installing the systems would still be $100 better off a year, even when paying off a typical $10,000 system.
Energy Minister Simon Bridges said there was a role for solar power in New Zealand but not if subsidised by the Government and taxpayers.
"However you look at this, it's not going to help power prices, the solar power is more expensive, so therefore really either Government is subsiding that or the Government's forcing that onto the power companies who of course will pass that through in higher prices."
Mr Bridges said New Zealand already generates 75 percent of its electricity from renewable sources.
The Labour Party says the Green Party's new energy policy looks sensible and could be worth considering if the two parties formed a government after the next election.
Labour leader David Cunliffe said the cost of such systems can be a barrier to households who would like them.
He said the idea of using a low interest loan may well work, but Labour would have to consider details such as how the roll-out is managed and what role the lines company might play.
Mr Cunliffe said Labour's goal is at least 90 percent renewable electricity generation by 2025.