Combining solar and battery power for an off-grid solution


Logan City Council in South East Queensland has successfully installed the first off-grid system powered by Bradford Solar and Tesla Powerpack products in Australia. The combined solar and battery power system now produces 100 per cent of the energy needs for water disinfection at the Round Mountain Reservoir. Here, we explore the considerations made and the challenges that were overcome when installing this innovative system.

First brought into service in 2014, the 20 megalitre Round Mountain Reservoir can provide clean drinking water for to up to 200,000 local residents in the Flagstone, Yarrabilba, North Maclean, Spring Mountain and Woodhill areas.

While the area is set to be one of the fastest growing areas in South East Queensland over the next two decades, Logan City Council Mayor, Luke Smith, was concerned with the issues that could arise from building assets larger than what is currently necessary.

“We were concerned that until demand increases, water stored in the network may age and not stay at the highest possible quality,” Mayor Smith said.

“We decided there was a need for a dedicated water chlorination station at the reservoir. The reservoir site is not connected to mains power or accessible via a sealed road so an innovative approach was required to maintain water quality from the reservoir.”

The Council’s Logan Water Infrastructure Alliance began investigating potential solutions to the power problem at the reservoir. The connection of mains power to the reservoir was explored but eventually not pursued due to its high cost.

“The solar power and battery system had a lower capital cost than a grid connection, avoided a premature investment in the road network and also saves approximately $50,000 per year in power charges,” Mayor Smith said.

Reflection and revisions

With the solar powered electro-chlorination facility confirmed as the preferred technology, CSR Bradford Energy was engaged to supply and install the solar and battery storage solution for the project.

Bradford Energy Business Manager, Ashleigh O’Brien, said there were a few challenges that were successfully overcome when installing the system.

“The reservoir roof was not originally designed for taking the weight and wind load of solar panels, which caused challenges in the design and installation of the system. Adding to this, the reservoir is also on top of a hill – meaning stronger wind loads than expected.

To overcome this, we did extensive engagement with a structural engineer and the mounting system manufacturer,” Ms O’Brien said.

“To give you an idea, we have done more than 10 revisions to the mounting system layout alone to get things 100 per cent right.”

As the project included one of the first Tesla Powerpacks to be installed indoors in Australia, some considerations needed to be made as to the size and weight of the system.

“We also engaged with Logan Council early in the project to build wider and taller doors to allow for the entrance of the system, as well as creating enough space to service it,” Ms O’Brien said.

“We were able to overcome all the challenges we faced during the installation process, particularly around the reservoir not having been originally designed to accommodate the size and weight of battery and solar technology. For us, this reiterates the enormous potential of this technology to be adapted to the needs of infrastructure and public assets across the country.”

Let’s get technical

The project is the first of its kind in Australia and showcases the growing potential for Australian assets to achieve energy security through solar and battery technology.

The electro-chlorinator is powered by 323 solar panels and a 95kWh capacity Tesla Powerpack, that will help provide water quality 24 hours a day.

Mayor Smith said the total capacity of the solar array is 87kW peak and the system supplies 100 per cent of the energy needed to run the facility.

“The solar power produced on any day depends on the available sunlight. Production ranges from a minimum of 211kWh in June (winter) to 435kWh in December (summer). The average annual daily production capacity is 330kWh,” Mayor Smith said.

“All site power is generated by the solar panels. There is provision for a diesel generator to be used in an emergency.”

The project has already delivered the Logan City Council a capital cost saving of $1.9 million and operational cost savings valued at almost $50,000 per year.

Ms O’Brien said the Engineering team at Bradford Energy were meticulous in testing and ensuring the safety and robustness of the system by simulating real life consumption variations and also by isolating the solar system to simulate variable weather conditions and anticipate any potential system failures.

“Solar generation will automatically adjust according to the battery’s status to prevent overcharging or undercharging. Ongoing analysis will be supported by the systems comprehensive monitoring platform,” Ms O’Brien said.

The life of the off-grid system is expected to be at least 15 to 20 years.

Other applications combining solar and batteries

The successful installation of the hybrid system has promoted Logan City Council to think about future applications for the technology.

“Logan City Council will use the project as a model for other infrastructure where capital and/or operational savings may be achieved by on-site power generation,” Mayor smith said.

Bradford Energy has also seen a rise in enquiries about solar PV and Tesla Powerpack installations since the project’s success.

“We are excited for what the future holds in solar and battery storage, as we believe that this technology presents a clean and viable solution to energy challenges being experienced widely across Australia,” Ms O’Brien said. 


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