Bay of Plenty people are increasingly turning to solar power but experts warn it may not be the most sustainable energy option.

There were 468 solar connections in the Bay of Plenty at the end of March, up on 302 at the same time last year and 191 the previous one.

Of this year's connections, 443 were residential, 14 commercial and 11 industrial.

Energy Efficiency and Conservation Authority communications manager Jane O'Loughlin said these days most people were installing photovoltaic (PV) panels which created electricity from sunlight, rather than installing solar water heating.


Sustainability Options partner Phil Gregg said 30 to 40 per cent of household power consumption went into hot water and panels were an inefficient way to heat water.

For this, people were better off with solar water heating or a heat pump hot water system.

Mr Gregg said people should also reconsider replacing old appliances and look at improving insulation to save energy.

People too often installed solar without considering the consequences, he said.

If a solar generation system was too large, power would get exported. If a lot of houses were exporting, the grid would need to be upgraded. If everyone tried to go off the grid, the question arose of who would pay for the grid, which buildings such as churches and hospitals needed.

Mr Gregg said people were making the switch to solar because advertisers presented it as a good investment, and he thought solar use would continue to increase in the region.

Nationwide, there were 9506 solar connections at the end of March, up on 5756 at the same time in 2015 and 2709 on the previous year.

According to the Energy Efficiency and Conservation Authority, the main barrier to the uptake of solar energy was the cost.

Solar generation made up only 0.1 per cent of New Zealand's total renewable energy.

A recent report by the Concept Consulting Group on the effect of solar panels on greenhouse gas emissions said PV uptake was expected to displace generation from existing fossil-fuelled stations and therefore reduce emissions, in the short term.

However, it would have a limited effect in the medium term as uptake would substitute for new low-emission power stations such as wind and geothermal. This differed from most countries because the majority of New Zealand's electricity was generated from renewable sources and large-scale renewables were the cheapest option for future electricity supply in New Zealand.