“Ultimate test:” New Zealand solar farm powers through major flood event

A New Zealand solar farm has powered almost all the way through a major flood event, passing what the developers have described as “the ultimate test” of the project’s design and technology.

Lodestone Energy says its 42 megawatt (MW) Te Herenga o Te Rā solar farm in the North Island’s Bay of Plenty region was last week caught up in an extreme rainfall event described by meteorologists as an “atmospheric river.”

In a post on LinkedIn on Monday, Lodestone says the solar farm, which achieved first generation in December 2024, “remained fully operational until the last few millimetres of rain … when the operations team decided, out of caution, to disconnect from the grid and ride out the storm.”

“When the sun rose again, the water receded nearly as quickly as it came. The Lodestone team were able to quickly assess the site with thermal-camera drones, scanning each component and determining just how well the tracking solar technology and flood-mitigation design met the challenge,” the post says.

“The team discovered that the flood waters rose to levels designed for and the farm performed as the engineering team had expected – the farm fared well!

“After a big effort from the #NewPower and #Lodestone crew, who have been working hard over the weekend to complete inspections and testing, we’ve been able to recommence generation. We are once again harvesting the sunshine of Waiotahe Valley.”

Te Herenga o Te Rā – a named gifted by the local hapū Te Ūpokorehe, meaning “mooring place of the sun” – was built on the border of the Waiotahe River and designed as agrivoltaic project, preserving the agricultural and horticultural potential of the land.

But its location in a valley also meant its design needed to account for the probability of “a lot of water from time to time,” the LinkedIn post says – “and this week was the ultimate test!”

“Anticipating extreme weather conditions like this one requires painstaking reviews of every rise and dip in the terrain, and all the rainfall that has occurred in the area for as long as records have been kept.”

Taking all of this into account, the engineering approach for the solar farm included a special piling design going more than four meters deep and extra high placement of the solar panels.

“Considerations for rapid water flow, the possibility of floating debris, and the prospect of sliding embankments were also built into the equation,” the post says.

“Given how quickly the rain can come, the ability to stow the panels in a horizontal position from Lodestone’s remote control centre ultimately became a critical part of bracing for this amazing force of nature.

“In the end, while more costly than an average solar farm, raising the inverter stations and panel connection boxes high above the ground so the plant could continue to operate in more than a meter of water turned out to be the right choice.”