New Zealand’s largest solar farm to be built on water

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A megawatt-scale solar farm to be installed on top of a wastewater treatment pond has become the first floating PV project and the first megawatt-scale solar system confirmed for deployment in New Zealand. Funded and hosted by local water utility Watercare and delivered by Vector PowerSmart, the PV array will be floated atop the Rosedale wastewater treatment pond in Aukland.

According to Vector, the project will be more than twice the size of the country’s current largest solar array. It will consist of over 2,700 solar panels and 3,000 floating pontoons and generate enough electricity to power 200 average NZ homes for a year.

The array will be used to supplement electricity from the grid as well as cogeneration from biogas, which is already generated on-site from wastewater treatment. The electricity is used for pumping and aeration for natural bacteria that help break down the waste as part of the treatment process.

Vector Group CEO Simon Mackenzie and Watercare CEO Raveen Jaduram said the system would mark a number of firsts for New Zealand in terms of size and type of installation. “Even larger systems are already common overseas and with reports out of Australia of costs as low as 4-5c per kWh, when that scale arrives here we’ll see solar’s real potential to set a new cap on the wholesale market which over the past few days has been around double that,” Mackenzie said.

For the water utility, the project is a major step towards its goal of cutting its energy use by 8 GWh by 2022 and making its Mangere and Rosedale wastewater treatment plants energy self-sufficient by 2025. “As a large user of energy, it’s important that we look at ways of reducing our environmental footprint and becoming more self-sufficient. Innovative solutions like this on top of wastewater ponds are a smart way to reduce operational costs,” Jadurum said.

With floating PV reaching full market maturity and an increasing number of solar markets opening up to the technology, the growth trajectory of ‘floatovolatics’ is pronounced. A combination of space limitations, falling PV component costs, and the growth of bifacial technology are just a few reasons behind the trend.

In a report released in November, the World Bank said global operational floating PV capacity had topped 1.1 GW, noting that adding floating solar to hydropower plants improves their flexibility while increasing energy yields. According to the report, Australia and Oceania have potential for 5 GW of floating solar on freshwater man-made reservoirs under conservative assumptions, and up to 50 GW under the most favorable scenario.

Despite huge potential, the floating solar PV market in neighboring Australia is likewise in its nascent stage. The nation’s largest floating solar farm to date – a 100 kW floating PV array – installed atop an overflow pond at the East Lismore Sewage Treatment Plant was launched last year. The Lismore plant is also Australia’s first community-funded council-owned solar PV farm.