An Auckland wastewater pond has become a power pod, with a one hectare solar panel system now floating on its surface.
Auckland Council unveiled their latest energy efficient initiative today, utilising what's usually untouched surface area at one of the city's water treatment plants.
The floating installation, with 2700 panels, is a solar first for New Zealand.
"This is the biggest solar array anywhere in the country and the first time we've put it on water," said Auckland Mayor Phil Goff.
And with the sun shining today, it was in full action.
"Today we're actually peaking on the system," Vector Powersmart manager Rogier Simons said.
The initiative's part of a plan to make the Rosedale Wastewater treatment facility on Auckland's North Shore, and the plant at Mangere, energy neutral by 2025.
Raveen Jaduram, Watercare chief executive said, "we like to innovative.. and we are very aware of climate change.. electricity is the challenge for us, we use a lot of electricity."
"I must say, I didn't know whether we could do it, it was like 'we will do it' and we're doing it. So I'm very proud," he said.
The biogas from sewage already produces up to 70 per cent of the electricity needed at the North Shore plant, and the new solar array will provide another 25 per cent.
"That's 95 per cent and we're doing a few other initiatives and we'll get to our 100 well before 2025," Jaduram said.
The total annual output of the one hectare array is close to 1,500 megawatt hours, enough to power the equivalent of 200 average kiwi homes for a year.
"It will be used for pumping the sewage within the plant, and also to run the aeraters... that put air into the sewage," Jaduram said.
Goff said, "It stops us putting 145 tonnes of carbon dioxide in the air each year, so this is environmentally sensitive but it also pays for itself, 4.5 million in savings over the life of the plant."
The team at Vector Powersmart has spent four months building the installation, drawing on past experience.
"For the last decade we've been working in the islands over 18 attols, building large scale micro grid solar systems and large scale battery systems.. so for the team it wasn't the largest system but putting it on water definitely was a nice challenge for them," Simons said.
But Simons said floating solar isn't new, "Japan has very large ones, we have large ones in England.. on the Thames".
Goff said the wastewater pond, turned solar farm, will possibly be used as a drinking source in the future.
"We welcome the sun, because it powers the plant behind us, but actually we welcome the rain, our lakes are still at 67 per cent capacity," he said.