A dairy farming co-operative in eastern Victoria has installed a 61kW ground-mounted solar system, and is considering plans to add Tesla battery storage, as it seeks to cut grid power consumption and change the way it thinks about energy.
The Macalister Demonstration Farm, in Riverslea, near Maffra, is a commercial dairy farm focused on using science and demonstration to stimulate the take-up of innovative practices to boost productivity and profitability.
First established in 1960, the co-op’s board had weighed up adding solar almost 10 years ago, but after being approached by a local Gippsland installer earlier this year, they determined the timing and the economics to be right.
“The quality of the technology, the cost of the technology and more importantly, access to finance, these three things have come together beautifully and made this a no brainer,” said MDF Chairman, Neil Baker.
As the MDF 2018 Annual Report notes, the brief to installer Rockys Solar was to design a system that delivered a power bill for the dairy of $0.00, or as close to, while also cutting its carbon footprint.
The upshot was a 61.38kW ground mounted solar system, sited in the old hay-shed paddock, made up of 186 premium Tier 1 Jinko Solar panels and two 27.5kW ABB Inverters.
As you can see in the chart below, the system generates 266kWh/day, while the diary’s average daily consumption is 154kWh/day.
According to the annual report, the co-op’s board opted to generate 112kWh/day of surplus for a number of reasons, including that exports to the grid represented a new income stream for the farm.
“We want to cover the service charges, as well as the cost of buying power,” the report said.
“You can see from the green bar that we are only using a bit less than half of our own generated power – that’s because our demand for power during the day is limited to a little bit of chilling, the afternoon milking and heating hot water if we switch away from night rate.
“The rest of the power we need we will be drawing from the grid in the hours that we are not generating enough to run the dairy.
“There is very little load during the day so most of what we generate goes back to the grid to compensate for our power usage outside daylight hours.
“Of course, we’ll be monitoring and reporting all of this to see that our projections match reality to give you confidence if you choose to make a similar investment.”
The MDF said it has also considered including a Tesla battery system “big enough for us to operated off-grid and overcome issues of power outages,” but would wait a few years, until the costs of doing so had fallen, or the solar system debt was reduced.
“From a demonstration point of view I think that’s important,” Baker told Rockys Solar.
“Batteries will enable a reliability and continuity of supply which is particularly critical in areas that experience frequent interruptions to grid supplied power without the need for massive generators.”
On its own, the solar system has been estimated to have a payback period of around six years – although the Annual Report notes that this time-frame changes “every time with have a rise in tariff.
“Our calculations have been made assuming a Peak Tariff of 22.1c/kWh and Off-Peak at 11.7c/kWh. Since then (construction began in July) power prices have risen by 4 and 2c/kWh respectively, bringing the payback period down even further.”
And Rockys notes that the addition of solar at the co-op has fostered a new way of thinking about how things are done on the farm.
“They are considering a different approach for everything from milking times, to crushing grain, and irrigation methods,” the installer says.
“Tasks that would normally be relegated to off-peak times can now be done during the day when free power is available which also saves on labour costs.
“Being able to run sprinklers at no cost during the day when visibility is also high is a great advantage.”
The co-op also believes the ability to expand the solar system in the future will allow for an increase spray irrigation and other practices the MDF board hadn’t considered economically viable in the past.
“Adding extra spray irrigation would enable us to grow so much more grass, which is money in the bank,” Baker said.
“When we change the way we think about the cost of power, we can see opportunities.”