'We haven’t had a power bill in five years': the Wairarapa couple living off-grid

Frank and Lisa Cornelissen, who own and operate the Martinborough Top 10 Holiday Park, built a house themselves during the Covid lockdowns on land they bought in 2018.

Sitting on three acres of old grazing paddock to the south of the township, the house has spectacular views across Lake Wairarapa to the Tararua ranges beyond.

The decision to go down the self-sufficiency route was in part prompted by hard economics, Frank Cornelissen says.

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Firstly, the section they bought was “reasonably well priced” but had no power.

“The price for power was $27,000 just to connect.”

That “big pile of cash” instead was invested by the couple in their own power generating set-up.

“We always wanted to go off-grid and give it a try.”

The couple's experiences are very much 'learn by doing', Cornelissen says.

“It’s the Dunning Kruger effect in operation. So, you think you know what you're doing, but really you don't!”

The house is now powered by 23 solar panels and a wind turbine with a cluster of lead carbon batteries housed in an outbuilding to store the energy.

The panels are placed on the land around the house to maximise the sunlight falling on them – in summer and particularly winter.

For most of the year power is abundant, Cornelissen says.

“I thought you’ve just got to make as much power as you can, right? But it doesn't really work like that.

“What you’ve got to be able to do is get through winter - winter is all that matters. You’ve got to be able to make enough power when it's really grey and really still, in the middle of winter.”

They do have a back-up generator for those frigid mid-winter days, but it has rarely been used, he says.

An hour or two of sunlight, even in June, is enough to fill the batteries for the night, and the wind turbine clicks away on cloudy days and overnight.

The panels generate DC electricity, which is then channelled through an inverter conversion unit to provide AC electricity for the house.

On a sunny, windy day, like the one when RNZ visited, the batteries were already full, so the system was making energy to directly power the house.

The dishwasher, fridge, lights, laptops and the septic tank were all running and the EV was charging.

All up the system was generating about 4kw, most of that power going to the car.

The maximum they can generate is 9kw from the solar arrays and 800w from the wind turbine.

When the batteries are full, an inverter turns down the solar panels, so they only generate whatever power is needed at that time to run the house.

The turbine on the other hand, was clicking away making 300w - the system can either use that power or dump it – you can’t turn down or turn off a turbine.

Cornelissen says the economics of off-grid power generation make more and more sense as the price of kit comes down.

“Pretty consistently, while I was doing this, it was about a dollar a watt. So, a 400-watt panel cost $400.

“You can get these 400-watt panels now for about $175. So, if you've got the space, my advice to anyone is just put on as many panels as you can.”

While the eventual cost of the set-up was higher than budgeted, and there were some missteps with the placement of the panels and a blown-out turbine, the couple are still ahead, Cornelissen says.

“We've been under our own steam for five years and haven’t had a power bill in five years.”

The energy efficient house is heated by a wood burner, which keeps it cosy in winter.

Growing conditions are tough in the Wairarapa, with hot dry summers and cold winters – and it blows hard too.

The Cornelissens are establishing a wildflower meadow, irrigated with grey water, to attract bees for the veggies. They're planting lavender and hundreds of native trees and shrubs they have raised themselves as seedlings.

While the elevated position means the winds can be gnarly, the views are spectacular, Cornelissen says.

“We can see the whole length of the lake. You can see the balloons over Carterton, you can see Featherston and Greytown and the snowy hills in winter.”