Australia's largest PV system

by the CADDET Australian National Team

In 1995, Western Power commissioned Australia's largest PV system - a 20 kW, grid-connected plant, located at Kalbarri in Western Australia. The plant's purpose is to demonstrate a state-of-the-art current-controlled inverter, which was developed locally, and to provide data and operational experience to help assess the benefits of photovoltaic installations in Australian conditions. The project has fulfilled these purposes very successfully.

The Kalbarri 20 kW photovoltaic system.

Background

The Kalbarri PV system began as part of a joint research venture between Western Power Corporation, Advanced Energy Systems Ltd, Murdoch University Energy Research Institute, Curtin University Power Electronics Research Unit (now CRESTA) and the Federal Government's Energy Research and Development Corporation. The aim was to develop state-of-the-art electronic power inverters to enable power from photovoltaic systems to be fed into main power grids or small, remote mini-grids.

Kalbarri, situated at the end of a 136 km distribution line at the northern extremity of Western Power's main grid for the town of Perth, was an ideal site for a demonstration of a large grid-connected PV system. The project combines a power inverter with a new adaptive control system and PV panels that track the sun.

Benefits

Voltage fluctuations and high electrical transmission losses are typical of many remote locations in Australia. The connection of PV panels using advanced control technology can help to alleviate these problems, although the demonstration system at Kalbarri is too small to have a significant impact on town peak demands of around 3 MW. Environmental benefits include reduced production of greenhouse gases and other air pollutants, as the PV system replaces some energy generation from fossil fuels. Electrical losses from the distant conventional power sources are also reduced, since the PV system is a local power supply.

The PV system

There are 16 tilted, single-axis trackers, each supporting 16 PV panels - a total of 256 panels. The trackers can be adjusted manually to maximise seasonal performance. The panels use state-of-the-art crystalline silicon solar cell technology developed in Australia and have a rated peak efficiency of 16.5%.

The 35 kVA 3-phase, current-controlled power inverter was designed and manufactured locally. Its control system has two functions: automatic maximum power point tracking and automatic AC voltage regulation to help eliminate problems caused by changing levels of demand.

Grid connection is via a 100 kVA transformer. Protection of the inverter-to-grid interface is based on voltage and frequency ranges, excessive current limits and reverse power limits.

Depending on local weather conditions, the PV system can deliver up to 20 kW of electricity.

Energy export performance data from the Kalbarri system.

Performance

Monitoring began in June 1996. The system exported 38.6 MWh in 1996/97. Potentially, the system could generate 44 MWh/ year and the avoided transmission line losses could amount to about 9 MWh/year. Output was reduced in some months because of tracker and inverter repairs. Peak inverter efficiency proved to be over 90% across the entire range of operation.

Kalbarri's energy demand is summer peaking, with the demand highest from midday to early evening due to air-conditioning loads. This matches well with the output from the PV system and thus maximises transmission savings from reduced line losses.

Economics

The capital cost of the project from site development to system start-up was about A$450,000 (where A$ is the Australian dollar), excluding monitoring system costs and Western Power project management. The PV array and tracking system accounted for 50% of the A$22/watt cost.

For more information contact the CADDET Australian National Team.

The CADDET Renewable Energy Newsletter is a quarterly magazine published by the CADDET Centre for Renewable Energy at ETSU, UK.

The articles published in the Newsletter reflect the opinions of the authors. They do not necessarily reflect the official view of CADDET.

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Pauline Toole, Editor, CADDET Centre for Renewable Energy, ETSU, Harwell, Oxfordshire OX11 0RA, United Kingdom. Tel: +44 1235 432968, Fax: +44 1235 433595.