Collins Square, Docklands, Melbourne

WINNER: Graeme McMullan for Energy Action

A commercial solar solution in downtown Melbourne is a trophy for any landlord, and when it helps lift a building’s NABERS rating to 6 stars it’s generally considered a sound investment that will also benefit tenants.

The brief to Energy Action was to come up with a solar system that would facilitate a NABERS rating uplift, make maximum use of the available roof space, interface with an onsite gas cogeneration system and emergency back-up generator, stick to Citipower’s export limits and work with the existing building management system.15-100kw-5_small

Significant challenges were overcome in installing a tilted system at a height of 18 storeys, says Graeme McMullan of Energy Action, and developing an intelligent interface with the onsite gas turbine cogeneration system. The result was “an aesthetically excellent system” which offset grid consumption and achieved more efficient operation of the gas turbine cogeneration system.

“With a combination of three energy sources the building can dynamically alter where it draws its power from based on the demand and the availability and cost of energy from each of the resources,” McMullan says. “For instance, if the cost of gas generation is less than electricity from the grid at a particular time the building management system will ramp up the cogen output to supplement the PV generation to support the load.”

The design leaves the option open for storage in the future, where the owner may enter into an arrangement with the retailer to export energy to the grid at times of high spot price and to lop peaks in energy use.

To keep things looking trim, durable and safe, DC and AC cable runs were housed within covered cable tray and a claw-style, clamp-less framing system provided a neat appearance.

There were a few challenges, McMullan says, including rooftop obstacles, static lines and access ways. “Operating in a multi storey environment and the issues associated with managing OH&S risk together with exposure, wind and transporting of materials to the roof posed significant installation challenges,” he says. “The roof also has a significant number of skylights as well as vent for high temperature steam from the cogeneration system.”

Other than being a hit with the judges, the project scored well with the owners. “The blended aesthetic appearance of the solar array and the seamless integration of all physical aspects of the system with the existing building infrastructure were stand out features of the project but the thing they like best is the engineering solution that allows them to get a NABERS uplift whilst at the same time achieving a sophisticated interface with the gas cogeneration system,” McMullan says.

“This allows the owner the attractive opportunity of choosing between three sources of energy and also in future for storing weekend excess energy for use in peak times during the week. The client is also considering negotiating with the network authority and retailer for virtual net metering which will allow them possibly to net off the power exported in the adjoining properties.”

The system is expected to provide savings of more than $14,000 a year.

McMullan acknowledges the Collins Square Management Team for proving great support. “A highly efficient management team delivering 6 Star NABERS Buildings was an absolute pleasure to work with.”

PROJECT DETAILS

Project name: 99.905kW Solar PV Installation, Collins Square, Melbourne

Location: Tower 3, 747 Collins Street

Owner: CIMB TrustCapital

Developer/contractor: Energy Action (Australia)

Capacity: 99.905kW

Commissioned when: July 28, 2016

Key equipment installed: Trina Honey Polycrystalline 265W x 377, Inverters SMA STP, Array frame

Energy usage: 882MWh a year

Expected payback period: 12.26 years

WHAT THE JUDGES SAID:

This system on Collins Square, in Melbourne’s Docklands precinct, features a sophisticated integration of an existing gas cogeneration system, with pleasing aesthetics for the benefit of neighbouring office towers. The project helped the client achieve a 6-star NABERS rating. In designing the system, Energy Action had to deal with some overshadowing from a neighbouring tower, high wind loadings and an installation 18 storeys up. The drop in output on winter mornings from the overshadowing is presumed to be offset by the relative increase in summer output, relative to not having the shaded areas available for PV output at all, thus yielding a net annual advantage.

Australian Centre for Advanced Photovoltaics chief operating officer Dr Richard Corkish and Envirotecture director Dick Clarke.