Unison Network's increased tariff for solar electricity generators using its network has been given the green light by the Electricity Authority.

It was alleged Unison had breached the Electricity Industry Participation Code, but authority chief executive Carl Hansen said the part of the code cited did not apply to tariffs between distributors and retailers.

Unison introduced the higher tariff in April, saying solar electricity generators connected to its network were subsidised by other power consumers because they were likely to be contributing to peak demand at evenings and early mornings.

It said home electricity generators paid about $300 less than other customers annually but received the same level of service, typically using the national grid during peak demand.

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The increased tariff is for new installations. Existing solar customers remain on their current rate until March 2019.

Hansen said Unison's tariff was not as cost-reflective as it could be, but it did not breach the code.

"Unison has informed us that its new pricing is an interim step towards our preferred approaches, as it considers it is currently constrained by incomplete roll-out of smart meters and limitations in retailers' billing systems, which are necessary requirements for service-based prices," he said.

Visiting Hawke's Bay last night, Green Party co-leader James Shaw said the authority had been captured by partners of the industry who were dealing with changes in the energy market in a defensive way.

"In any decision up for change, entrenched companies dig in and say they're not going to change. Companies that can adapt come out in front," Shaw said.

He said such charges discouraged those who wanted to switch to solar, when people should be encouraged to change.

Greenpeace climate campaigner Simon Boxer said Unison's charge put a tax on solar.

"This is a blatant move by the authority to wash its hands of protecting and promoting renewable energy like solar so that it can continue to massage New Zealand's electricity monopoly."

Unison general manager of business assurance Nathan Strong said it was pleased the Electricity Authority acknowledged there was no difference between a customer with solar panels and the average customer "in terms of their reliance on our network to supply them with electricity at peak times and in winter, regardless of how much electricity is used overall".

"Those customers who can't afford or are unable to install solar shouldn't have to carry the cost of the network being available to those who do.