DOC to install NZ’s largest off-grid solar power system on Motutapu Island

Installation of New Zealand’s largest off-grid solar power system will begin next week on the Department of Conservation-managed Motutapu Island.

The $768,000 solar make-over is part of DOC’s ongoing Sustainability Programme, which aims to boost DOC’s renewable energy use and halve its diesel fuel bills.

The Motutapu solar project is expected to generate at least 65,000kWh per year, providing up to 70% of the island’s energy requirements.

“We’re currently using a diesel generator to supply power for the island, and once this investment is complete we’ll be using the sun to provide most of our power,” says DOC’s Auckland area manager Brett Butland.

“We’re thrilled to be announcing during Conservation Week that we’re moving towards an environmentally sustainable method of producing power on Motutapu. Now that both Rangitoto and Motutapu are well on their way to becoming pest-free sanctuaries, it’s great to be ensuring our power generation has as little environmental cost as possible.”

Power Technology Components Ltd won the tender for the project, and will supply and install the photovoltaic modules (solar panels), invertors and batteries. The solar panels will be installed on the barracks buildings at the Motutapu Outdoor Education Camp (MOEC).

“The roofs of the barracks buildings are near ideal for mounting solar panels. The orientation and incline of the roofs are perfect to make the most of local sun angles,” says Mr Butland.

Power on the island supplies a number of DOC houses (where staff and contractors live while carrying out conservation work), the 12,000 guests per annum that stay at MOEC, and Motutapu Farm.

Once the renewable power generation system is complete, the power and water distribution networks on the island will also be upgraded. Cost savings associated with replacing the current system are estimated to be $188,000 per year.

There will be big savings once the water reticulation system on Motutapu Farm is upgraded, as it currently accounts for about a third of the power use on the island.

“Thanks to recent developments in solar pump technology, it will now be possible for the pumps to generate the volume and head of water we need through the sun,” says Mr Butland.

Another part of the Sustainability Programme is a project to install solar hot water systems at DOC recreational areas. This project will cut DOC’s island hot water energy bill by around 80%, and the systems will pay for themselves within five years. This project is a 50/50 partnership with DOC and the Energy Efficiency and Conservation Authority (EECA).

On Motutapu, several solar hot water projects have already been completed. At MOEC, two systems of just under 1000 litres each were installed by Azzuro Solar Ltd between April and June this year. The MOEC Trust provided nearly 50% of the funding for the project.

MOEC manager Duncan Watson is very pleased with how the system is operating so far. He says the system is currently returning an average of 20-25 kWh per day despite low sunlight levels, and he expects much greater returns over the critical peak summer months.

“We operate 365 days a year, so our requirement for a reliable, plentiful, cost-effective and environmentally sound hot water system is massive,” says Mr Watson.

The project is expected to save about 15,700kWh of power and avoid about 10,500kg of CO2 being released into the atmosphere each year. It should save about $74 a day.

Another solar hot water project on Motutapu — completed in June this year — saw Solar Group Ltd install hot water systems on four houses on Motutapu.

ENDS

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