Solar farm first step to reduce Stewart Island diesel reliance

The first step to reduce electricity costs for Stewart Island Rakiura residents is to create a solar energy area with batteries, which could replace up to 75% of diesel used once it is implemented.

Mayor Rob Scott, councillor Jon Spraggon and community board chair Aaron Conner with PTM Consulting technical experts explained the approach to about 80 islanders at a meeting there last month.

“It has been the steering group’s priority to get something done about the cost of electricity on the island for the past 18 months, as the impact on islanders is high, and this has been a talking point for several years,” says Scott.

The Southland District Council secured $300,000 of government funding and hired PTM to carry out a significant project to advise it of the next best steps.

The draft document was given to the steering group just before Christmas in December 2024 and is available on the council’s website.

PTM has recommended going with a 2MW solar farm and a 4MWh battery providing about 75% diesel displacement (option four) as being the best value, the council says.

“We have agreed that a staged approach will be the best way to achieve immediate benefits and to go with the recommended option, which will not only reduce reliance on diesel to a large extent but also be a more future proof solution,” says Scott.

“The first stage is to create a solar energy farm with batteries on appropriate land. This will supplement the diesel generators, not replace them, and so improvements are planned for the whole network and to ensure the generators are operating in the most efficient way,” he says.

The second stage involves implementing another source of renewable energy, possibly wind.

The council says further investigation of the source is planned while implementation of stage one is underway.

The goal is to enable electricity on the island to be generated by renewable energy so that not only will residents have a reliable and relatively affordable solution for their electricity needs, but economic development in the form of tourism and aquaculture can also be enhanced for the island, the council says.

Scott says: “Council will be submitting a proposal to the Regional Infrastructure Fund for the funding of this project very soon as it will be impossible for 400 residents to cover the capital costs.”

Meanwhile, Radio New Zealand (RNZ) says the Electricity Authority’s Energy Competition Taskforce has three proposals to give people more control of their power prices and to make better use of rooftop solar and batteries.