Calder Stewart plans $110m rooftop solar and battery rollout

New Zealand’s largest industrial landowner plans to invest more than $110 million in rooftop solar and battery storage over the next decade, saying the initiative will lower electricity costs for businesses while reducing pressure on the national grid.

Calder Stewart plans to install up to 170,000 solar panels across its industrial property portfolio, creating up to 85MW of rooftop solar generation capacity supported by battery storage systems.

The company has more than 900 hectares of zoned industrial land across Auckland, Canterbury, Otago and Southland, providing one of the country’s largest platforms for distributed energy generation.

Its energy division has already installed solar systems across 17 industrial sites, covering more than 152,000m² of roof space and capable of generating 3.6MW at peak output. The systems are expected to produce about 4.2GWh of electricity annually, equivalent to the power consumption of more than 500 homes.

Director Sam Stewart says wider adoption of rooftop solar across industrial properties could save millions of dollars in avoided transmission and distribution costs while reducing the need for further investment in electricity infrastructure.

“If your meter says you have used 100 kilowatt hours, you may actually pay for 105 because of the losses across the network.

“By generating power above where it is used, we can take pressure off the lines network and reduce the cost of moving electricity across the system,” he says.

Stewart says solar will become a standard feature of Calder Stewart’s future industrial developments, while many existing buildings are expected to be retrofitted within the next year.

He says reducing the delivered cost of electricity could help improve competitiveness for manufacturers, logistics operators and other energy-intensive businesses.

“Every percentage point matters when businesses are operating in competitive markets.

“If we can help reduce one of the core operating costs for industrial occupiers, that ultimately supports lower-cost production, stronger margins and a more competitive export sector.”

Stewart says industrial rooftops have historically been an underutilised asset despite their scale and proximity to major electricity users.

“We build these buildings and the roof is sitting there unused. The opportunity is to turn that into a productive asset that supports the tenant, supports the grid and creates a long-term return.

“Our model also avoids some of the land-use tensions associated with large-scale ground-mounted solar by using industrial roof space that would otherwise sit idle.”

Calder Stewart Energy manager Ben Krieble says tenants can access lower-cost solar energy without funding or owning the infrastructure.

“Because the generation is on the roof, there are no lines charges, no network transmission losses and no levies attached to that portion of the electricity.

“That allows us to undercut the normal retail power cost because we are generating the power where it is being used.”

Krieble says the company can also offer longer-term power pricing arrangements to provide greater certainty for industrial customers facing rising electricity and network costs.

“It is like fixing a mortgage for a longer term. On the backdrop of rising electricity prices and lines charges, fixing that operational cost line gives businesses more certainty as they plan ahead.”

The company also plans to deploy battery storage systems to store excess solar generation and reduce demand on the grid during peak periods.

Stewart says the batteries could help reduce strain on local electricity networks during morning and evening demand peaks.

“The two peak periods in New Zealand are first thing in the morning and around six o’clock at night. If power has been stored onsite, or batteries have been topped up overnight when electricity is cheaper, that power can be used instead of drawing from the grid at peak times.

“That has benefits beyond the individual occupier. It helps reduce stress on the national grid and local networks.”

Krieble says a large-scale rollout of solar and batteries across the portfolio could eventually operate as a virtual power plant.

“When you have distributed generation and batteries across a portfolio, it is not just a generation asset. It can provide services to the network, reduce demand when the grid is under pressure and keep buildings operating from stored power,” he says.

The rooftop solar programme forms part of a broader energy strategy that also includes investigating utility-scale wind generation opportunities across Calder Stewart’s wider land portfolio.