Off-grid solar to cut diesel use by 60% at NSW cotton farm

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November 18, 2015 11:10 am

A cotton farm in NSW will use an off-grid, hybrid solar plant to power the irrigation of its crops, after it switched on the new system on Tuesday.
The cotton farm in Moree – which is also the host to one of Australia’s biggest solar projects, the under-construction 56MW Moree Solar Farm – has added a 70kW ground-mounted solar array with back-up battery storage to its diesel engine direct drive pump, with the aim of cutting its diesel consumption by 60 per cent.
The hybrid system, designed and installed by YellowDot Energy, uses variable frequency drive (VFD) technology to combines the electricity from the diesel generator and the solar PV.
This allows 24/7 operation of the irrigation bore pump, with the ability to pump high daily volumes using less than half the amount of diesel fuel.
According to YellowDot, the farm’s first-of-its kind power plant is designed around a proprietary electronic control system that includes a range of sensors and remote telematics.
This allows the farmer to choose to operate seasonally between hybrid and a solar-only mode and can monitor and control the system remotely via an internet connection.
“Lower diesel consumption means a lower extraction cost per ML of water,” said YellowDot chief engineer, Rob Mailler. “This lower cost allows an irrigator to expand their planting choices to crops that would not have been economically viable with diesel only pumping.”

The battery back-up, at only 2.4kWh – using VRLA (valve-regulated lead acid) batteries – is designed to act as a 24V power supply to run the control system when the hybrid power plant is in shutdown, YellowDot sales director Glenn Clark told One Step.

“This allows us to maintain communications to the site and allows remote startup and shutdown and changes to operating mode. The batteries are not connected to the drive or the pump load.”

Clark said the option to add in large battery storage for this application was there, but the economics didn’t justify it right now.

As it is, the diesel generator allows 24 hour operation during the cotton farm’s peak irrigation season – October to February inclusive. The system will run in solar only mode across the rest of the year.

In hybrid mode, the generator and the PV run together with the control system always looking to optimise the fuel use for the generator.

“We have a lot of irrigators who are interested in this technology and they are extremely conscious of the cost of diesel within their businesses,” Clark told One Step by email.

“It is, however, a new approach – we believe this site is a first for this type in Australia – so it is really the innovators and early adopters who are moving ahead for this application.

“I suspect that installing this type of power plant will become a widely accepted practice over time as farmers see the results being achieved and become comfortable with the technology.”

The plant’s technical specifications are as follows:

70kWp ground mounted solar PV
Tigo DC optimisers
45 kW ABB Variable Frequency Drive
PLC control system with remote communications and control
Battery UPS for control and communications
60kVA diesel generator with electronic controller
Submersible 3 phase pump manufactured and installed by Condamine Drilling

Sophie Vorrath

Sophie is editor of One Step Off The Grid and deputy editor of its sister site, Renew Economy. Sophie has been writing about clean energy for more than a decade.

This post was published on November 18, 2015 11:10 am