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Project Summary 
System size11.5kW of solar paired to PB40 (7.5kW/ 40kWh) Freedom PowerBank off-grid unit and 14kVA diesel generator
System configurationAC coupled solar system supports load directly with battery system
Daily average system output52kWh average solar contribution per day
CO2 savings (per annum)14.36 tons


ZEN Energy installed a 48-panel solar system at Motpena Station, near the Flinders Ranges in South Australia, in March 2014. The 11.5kW system has drastically reduced the station’s reliance on diesel, helping to put an end to ever increasing fuel costs.

Project background

Motpena Station is a beef cattle fattening property located 420km north of Adelaide, South Australia. Owned by the Fels family since 1994, the 54,500ha station near the Flinders Ranges has about 1000 head of cattle. Barbara and Darryl Fels live on the property with son Troy, and are regular hosts to visitors.

Motpena Station is not connected to the electricity grid and is about 15km from the nearest diesel power micro grid provided by SA Power Networks, at Parachilna.
The property was relying almost entirely on diesel generated power, with an ageing solar tracking unit and wet lead acid battery system providing a small amount of electricity.

The solar unit had delamination of its solar cells, which had greatly reduced its output, and the battery system was corroded.
With summer temperatures reaching 46°C an evaporative air-conditioning unit had recently been installed at the homestead. This placed additional load on the diesel, increasing an already expensive fuel bill.

The homestead and station workshop were consuming about 24kWh of electricity during summer and an average 18kWh during winter to power a range of appliances, lights, chillers, compressors and workshop tools.

Wanting to put an end to rising diesel fuel bills, the Fels approached ZEN Energy to design a solar system that would cover nearly all of their energy use.

ZEN’s world-class products, the knowledge offered by ZEN’s staff and the cost of the system convinced the Fels to look no further for their solar system.

Designing the project

ZEN’s challenge was to design a solar energy system that would drastically cut Motpena Station’s diesel run time. ZEN’s staff spent time understanding the family’s needs at the remote property, and after careful assessment determined an 11.5kW ground-mounted solar system with a 40kWh lithium battery to provide up to 3 days of autonomy.

They surveyed the site for existing irrigation and trees, and agreed the most efficient site for the solar system was 30m from the diesel generator. As the ground was sandy, a concrete base was utilised and new distribution board installed. It was decided to use two German- made Kaco inverters and a 7.5kW Australian-made bidirectional inverter, to take advantage of the advanced communication offering and high level of power control.

How the system works

The electricity generated by the solar system is being used to power the homestead and station workshop. Excess power is stored in lithium batteries to be used at times when the system is not generating power, such as at night. In the two months following the system’s installation, the diesel generator has run only to self exercise.

System benefits

Using lithium batteries rather than standard rechargeable batteries offers many benefits, most notably improving the overall system efficiency by up to 20 per cent. This, in turn, helps to further reduce fuel costs and extend the life of the fuel generators.

Other system benefits include:

  • No battery maintenance, other than cleaning container fan filters in dusty environments;
  • It is AC coupled meaning the solar system can feed the load of the homestead and workshop with the excess recharging the batteries;
  • Its control system can intelligently communicate with the fuel generator and the solar system to operate in parallel. The system will assess the amount of charge available in the battery and if there is not enough to support the load, it will call on the diesel generator for a top up;
  • It is compact – 40kWh of batteries can be housed in a system not much bigger than a single door, 420-litre refrigerator;
  • It does not vent any hydrogen gases and therefore can be housed within the homestead in much cooler temperatures, maximising the batteries’ life;
  • It enables the diesel to run more efficiently as lithium batteries can be recharged at the maximum output rate of the inverter until they are 100 per cent charged. This ensures the diesel is heavily loaded for short durations; reducing issues such as bore glazing.

Project outcomes

ZEN’s expert team delivered Motpena Station’s solar energy system on time and on budget. Barbara Fels was full of praise for ZEN’s staff, saying they were professional and courteous throughout the five-day installation.

“We have been very happy with the work,” Mrs Fels said, “Everything was neat and tidy when they left… They have done a wonderful job.”

She said after her experience, she would not hesitate to refer ZEN to anyone considering making the smart switch to solar energy and lithium batteries.

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Zen Energy PTY LTD

Level 2, 134 Fullarton Road
Rose Park
South Australia 5067

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Victoria 3000