Taranaki marae sees 400% power bill rise after solar install

Waitara’s Ōwae Marae is warning others to be wary when converting to solar energy after an over-engineered installation led to an electricity bill blowout. 

Poor advice and industry assumptions made the solar installation on Ōwae’s new wharekai in Taranaki unnecessarily expensive, Manukorihi Pā Trust secretary Roina Graham said. 

The sobering caution was given at He Ahi Kā, He Ao Hou, a community-focused conference leading into the Aotearoa Energy Summit in New Plymouth this week. 

Graham said the pā had hoped to save money with solar, but instead monthly bills had risen from $400 to as much as $2000. 

Trustees called in local renewable energy experts to assess the system. 

They found an expensive 300-kilovolt-ampere (kVA) transformer with excessive capacity had been installed. 

Graham said that size of transformer would usually serve 70 houses. 

“Why would you install that on the marae, attached to the kitchen? 

“I don’t know. I’m still dumbfounded.” 

The marae also had its fixed lines charge bumped up to a pricier level, as the high peak of electricity use (during events like tangihanga) meant it was regarded as a business. 

Ōwae was charged that business-rate lines charge, despite sitting dormant most days – unlike a typical business. 

The wharekai was opened two years ago but the power bill still rankles. Photo / Te Korimako o Taranaki 

The installer, HEL Rimu Electrical, said the project’s engineer specified the large transformer. 

Managing director Callum Margetts said the capacity was intended to serve potential new housing or other future buildings on the pā. 

“What’s not explained – and we see this a lot – is the actual line charges that come with having a large transformer like that,” Margetts said. 

“I’m talking about your monthly ongoing costs of having the capability to have that energy provided to a site.” 

On top of that, Ōwae had no contract to sell power back to the grid, so the marae’s electricity retailer simply took the excess solar generation without payment for three years. 

Eventually, the retail supplier refunded the lost earnings for taking the excess power – but the business lines charge and over-specified transformer remain. 

Finally, when any solar panel on the wharekai (dining hall) roof was shaded, the entire array connected to it would also quit generating. 

Graham said marae trustees or administrators needed to fully understand every aspect of planned solar installations and must keep a close eye on the rollout. 

“You need that knowledge on how things work within your own marae.” 

Ruka Te Moana of renewable-energy company Te Piringa Pūngao was one of the experts called in to figure out what went wrong. 

“This isn’t an isolated incident,” he told the conference. 

He advised other marae to be cautious. 

“We’ve got awesome organisations like Rewiring Aotearoa, Solar Sense and Tū Mai Ra Energy that are going around helping whānau [to avoid] unintended consequences, stuff like this happening.” 

But Te Moana said that wasn’t enough and systemic change was needed to bring fair charging options for marae. 

“We’re educating our whānau to operate in a space that isn’t changing: the space actually needs to change.” 

Te Moana said funding bodies increasingly demanded feasibility studies for solar projects, to avoid the need for remedial work. 

Ōwae was working out how to avoid the worst impacts through measures like making sure batteries handle the brunt of peak power demand. 

Going off-grid was being considered and might end up being the best option. 

Te Moana said the new Ngāmotu Marae being built in New Plymouth could learn lessons from Ōwae’s experience.