Energy Savers
Southern Downs

Stanthorpe Horticulture Farm

Energy Savings
Zucchini and Eggplant
Solar Photovoltaic, Lighting, Variable Speed Control
Capital Cost


A recent energy audit showed how improving the current systems can lead to energy and cost savings. The recommendations explored in the audit and implemented included installing Variable Speed Drives on pumps, lighting upgrades to LED in the packing shed and installing a 20kW solar PV system, with total energy savings of 99% and emission reductions of 23.2 tCO2-e per year.

The farm, near Stanthorpe, produces zucchini and eggplant and is irrigated for 9 months of the year, depending on rainfall. Water is supplied from an onsite irrigation dam and replenished from rainfall and bores. There is also a pump in the nearby Severn River. 

It is a small site consuming approximately 31,000kWh per year at a cost of $8,500. The farm produces around 190 tonnes of eggplants and zucchinis 

The infrastructure contributing to the energy consumption onsite consists of:

  • 5.5kW dam pump 
  • A packing shed with cold room 
  • 11kW river pump 
  • A small bore pump of unknown size 

A recent energy audit showed how improving the current systems can lead to energy and cost savings. The energy audit recommended the following changes to improve efficiency and reduce costs:

  • Installation of Variable Speed Drives on the pumps to better manage the different sizes and elevated blocks on the site and reduce the electricity consumption. 
  • Installation of a 20kW solar PV system on the packing shed.
  • Lighting upgrade to LED on the packing shed to reduce the electricity consumption for lighting by up to 50% and have a better light output, so fewer fittings are required. 

Table 1. Energy and cost savings from audit recommendations.

Recommendations Annual Energy Savings (kWh) Annual Cost Savings ($) Emission Savings (tCO2-e)  Capital Cost ($) Payback Period (years)
5.5kW VSD on dam pump  1,800 450 1.5 1,500 3.4
11kW VSD on river pump  1,020 250 0.8 2,750 11
20kW solar  22,000 6,000 17.8 26,000 4.25
Lighting upgrade  400 100 0.3 1,200 11.4
Total 25,220 6,800 20.4 31,450 7.5


The grower has proceeded with all the recommendationsmeasured in a Measurement and Verification (M&V) process, as outlined in Table 2.

Table 2. Estimated and Actual energy and cost savings. 

Metric  Audit estimation  M&V calculation  Variation (%) 
Energy Savings including exports (kWh)   25,220 28,690 14
Cost Savings including exports revenue ($) 6,800 3,700 -46


The lower cost savings compared to the estimated have been influenced by the low use of solar generation onsite. Only 9,400 kWh or 33% of total generation are being used onsite valued at $2,186, and 19,290 kWh are being exported to the grid with a revenue of $1,516. Considering that 19,600 kWh  – 68% of the total energy used onsite – are being imported from the grid at a cost of $4,560, there are significant potential savings from shifting consumption into the solar generation period. The total power balance of the farm, including solar exports and the energy cost distribution, are shown in the following figures.

Energy ES154

Cost ES154

The next step for the farm is to adjust energy usage to offset as much energy consumption as possible from the grid, which would lead to further cost savings. The revenue from feeding into the grid is lower than the cost savings from using the energy onsite: for every dollar of energy exported, around $3 could be saved if the energy were consumed onsite. If the farm were to shift 19,290kWh of energy consumption per year to coincide with solar generation times, they would save an extra $2,972 per year.

Solar optimisation ES154

From the implementation of recommendations in the audit, the farm has reduced energy consumption by 99% and costs by 48%, including feed-in revenuewith Carbon emission savings of 23.2 tCO2-e per year.

Table 3. Pre and post implementation energy, costs, and energy productivity improvements.

Metric Pre-Implementation (2020) Post-Implementation Reduction (%)
Energy Consumption (kWh) 29,000 310 99
Cost ($) 7,660 3,960 48
Energy Productivity (kWh/tonne) 115.8 1.6 99


An energy audit is a good investment. 

An energy audit is a great first step in moving a business towards a more efficient future by reducing energy use, costs and carbon emissions onsite.  

An energy auditor will review your past energy bills, your equipment and the way your business operates. They’ll show you where you’re using excess energy and explain what you can do about it. Find out about what’s involved in an energy audit HERE. 

See our range of agricultural energy efficiency case studies 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.