Energy Savers
Darling Downs

Western Downs Grains Farm

Energy Savings
Grains and Fodder
Solar Photovoltaic
Capital Cost


A Western Downs grain farm could benefit from saving both time and money from recommendations in a recent energy savers audit. The audit recommended replacing capacitors in silo aerator motors, installing humidity control in silos, LED lighting replacement, and a solar PV system to offset the energy consumption from the grid.

The farmer has implemented the solar PV system. Savings will be updated when the measurement and verification process is complete.

The farm produces and stores grain onsite using a variety of small single-phase motors driving silo aerators, and lift and conveyor systems, to supply fresh and stored grain in automated temperature-controlled silos.

The farm had an annual consumption of 28,671 kWh at a cost of $10,210 during the 2017-2018 period.

Energy use on farms can contribute to large operating costs. A recent energy audit showed how improving the current systems can lead to energy and cost savings. The recommendations explored in the audit included:

  • General silo motor maintenance with regular cleaning of the blades using compressed air can reduce excess demand. Energy efficiency is decreased when temperatures in a motor stator increase. The build-up of dust prevents the air cooling of the motor which leads to increased heat. This increase in heat reduces the life span of motors and as a result, they need to be replaced prematurely. This is a quick win at no cost.
  • Install new humidity control system in the silo and a hardwired power supply to new silo aerators.
  • Replacement of the phase shifting capacitors of old single-phase motors with more efficient units can lead to a 0.5kVA demand reduction and avoid burning out over time leading to poor power factors.
  • Replacing metal halides with new LEDs can decrease start-up current reducing demand and enable longer run times. LEDs have an increased life expectancy, run at lower temperatures and can decrease the number of lights required, due to being a superior source of light. Reductions in consumption and demand are commonly seen.
  • The audit also estimated cost savings of over $1200 per year by switching from the Obsolete Tariff 62 to Standard Business Tariff 20. It is recommended to reassess your current operating tariff every 12 months.

Table 1. Energy and cost savings from audit recommendations

Recommendations Humidity Control and hardwired power supply General Maintenance Capacitor replacement LED Lighting replacement TOTAL
Annual Energy Savings (kWh) 3,612 0 1,872 5,484
Demand Savings (kVA) 0 2.76 1.1  1.8 5.66
Annual Cost Savings ($) 1,975 375 375  588 3,313
Capital Cost ($) 19,500 0 480  2,700 22,680
Payback (years) 10 1.3 4.5 5.25
Emission Savings (tCO2-e) 2.9 0 0 1.5  4.4


Demand savings for a small electricity user may not directly reduce costs but may free up power capacity and reduce the risk of brownouts, particularly on farms that are serviced by Single Wire Earth Return (SWER) lines.

Two 10kW Solar PV options were considered, with and without a battery backup. The Auditor noted that:

  • The above humidity control needs to be implemented to make the solar system viable.
  • Export is unlikely to be possible from the site as it is serviced by a Single Wire Earth Return (SWER) line.
  • The solar system will be split into two separate systems across the incoming two phases, making two systems of 5kW each.
  • The switchboard needs upgrading to accommodate the new solar and this is incorporated into the costs below.
  • The savings below are based on the existing Obsolete Tariff 62 and the savings will decrease when the farm moves to a Standard Tariff 20.

Table 2. Energy and cost savings from Solar recommendations

Solution A.     2 x 5kW Solar Systems with Battery-ready inverter B.      2 x 5kW Solar Systems with 2 x 10kWh Batteries
Annual Energy Savings (kWh) 7,691 20,606
Demand Savings (kVA) Up to 10  Up to 10
Annual Cost Savings ($) 3,615 7,418
Capital Cost ($) 21,695 41,195
Payback (years) 6 5.5
Emission Savings (tCO2-e) 6.2 16.7


The grower has proceeded with the installation of the 2 x 5kW Solar Systems with a Battery-ready inverter (option A). Actual savings will be updated once the measurement and verification process is complete.

By installing the recommendations in the audit, the business is expected to reduce energy consumption by 27% and costs by 35%, with carbon emission savings of 6.2 tCO2-e per year.

Table 3. Pre and post audit energy and cost savings

Metric Pre-Audit Post-Audit Reduction (%)
Energy Consumption (kWh) 28,671 20,980 27
Cost ($) 10,210 6,595 35


An energy audit is a good investment 

An energy audit is a great way for a business to cut costs and boost productivity. Find out about what’s involved in an energy audit HERE and subscribe to our bi-monthly energy e-news HERE.

If you have any energy efficiency related questions for the team get in touch at energysavers@qff.org.au.

The Energy Savers Plus Extension Program is delivered by the Queensland Farmers Federation with support and funding from the Queensland Department of Energy and Public Works.