Diesel-dependent Tokelau is still on track to become the first entirely solar-powered places on Earth in a project led by a New Zealand solar company.

All three atolls in the South Pacific dependency, a New Zealand territory, will have their own solar power system by the end of October, despite a slight delay switching on the first system.

Once the project is complete, Tokelau will be the first country to meet 100 per cent of its climate change obligations and will only need fossil fuel to power its fleet of three cars.

Lead contractor Powersmart Solar is helping Tokelau replace its diesel generators - which burn about 200 litres of fuel daily - with 4032 solar panels, 392 inverters and 1344 batteries.

Powersmart Solar director Mike Bassett-Smith said the company was proud to be leading the project because of the impact it would have on the well-being of the people of Tokelau.

"All across the Pacific there are clear issues with the current and expected future costs of electricity generated using diesel, not to mention the environmental costs and risks of unloading diesel drums on tropical atolls," he said.

"Energy costs underpin the economic and social development of these nations and making a positive impact on these issues is the single most important reason we started this business."

Tokelau has a population of about 1400 and they have access to electricity for between 15-18 hours a day.

The solar power systems will be capable of providing 150 per cent of the annual electricity demand without increasing diesel demand.

Companies from all over the globe tendered for the project and it was a "big win" for the Mount Maunganui-based company, Bassett-Smith said.

The first solar system on the atoll of Fakaofo was due to be switched on this week but had been postponed for up to two weeks.

Bassett-Smith said the delay would not affect the schedule of the installations on the other atolls, with the next system to be switched on in about six weeks.

Tokelau's isolation and the scale of the project meant the system required significant testing and development in Mt Manganui before it could be moved to the atolls.

The system would be able to withstand cyclone force winds of up to 230kmh.

Bassett-Smith said Powersmart Solar could monitor how it was performing remotely and work with the Tokelauans to diagnose any issues.