Research
Areas:

1. Photovoltaic Fundamentals

2. Solar cells and modules

3. Solar concentrators

4. Low temperature solar

5. Energy and the Environment

Facilities

Andrew Blakers
Dr Vernie Everett

LINEAR (TROUGH) CONCENTRATORS

The ANU has developed a range of trough solar concentrators and components. The troughs can be configured to produce either electricity or heat or both.

Combined Heat and Power Solar (CHAPS) systems

Sun-tracking 2.5 square metre mirrors reflect light onto a receiver lined with solar cells. The solar cells are illuminated with approximately 25 times normal solar concentration, and convert about 20% of the sunlight into electricity. The balance of the solar energy is converted into heat, which is removed via water flowing in a channel behind the solar cells and stored for later use. A combined thermal and electrical efficiency of over 60% is achieved.

Photovoltaic trough concentrator

Sun-tracking 2.5 square metre mirrors reflect light onto a receiver lined with solar cells. The solar cells are illuminated with approximately 25 times normal solar concentration, and convert about 20% of the sunlight into electricity. The balance of the solar energy is converted into heat, which is removed via heat fins mounted behind the solar cells.

Thermal trough concentrator

Sun-tracking 2.5 square metre mirrors reflect light onto a thermal receiver such as an evacuated tube. A heat transfer fluid transfers the energy away from the receiver. The thermal energy can be used to create steam or drive chemical reactions.

Microconcentrators

Microconcentrator CHAPS systems can supply electricity and hot water to domestic dwellings. A four square meter, 20cm high, solar collector is mounted on the house roof. Narrow single-axis tracking mirrors concentrate sunlight onto narrow receivers lined with solar cells. The solar cells are illuminated with approximately 20 times normal solar concentration, and convert about 20% of the sunlight into electricity. The balance of the solar energy is converted into heat, which is removed via water flowing in a channel behind the solar cells and stored for later use in a ground-mounted tank. This technology takes advantage of the ideal characteristics of Sliver solar cells

Solar Cells

High-performance silicon solar cells for concentrator systems in the range 10-60 suns are being manufactured. An elegant process sequence allows high efficiencies (20-24%) to be obtained at moderate cost. Several thousand cells were fabricated for a demonstration photovoltaic/trough concentrator system at Rockingham in Perth and the Combined Heat and Power Solar (CHAPS) concentrator system at ANU's Bruce Hall

Solar Receivers

Concentrator solar cell receivers for use with parabolic trough concentrator systems have been developed. One version has a light weight, high-performance, patented, aluminium-fin heatsink. Another version has water cooling. The receivers feature thermal cycling stress relief, bypass diodes, high-quality encapsulation and high-performance silicon concentrator solar cells.

Mirrors

An elegant glass-on-metal-laminate (GOML) mirror technology has been developed. Thin rear-silvered glass mirrors are bonded to a coated steel sheet. Stamped tab ribs fitted to each end of the sheet impart the correct parabolic profile. This construction provides a mirror that is both lightweight and durable.

Mechanical structure

The support structure for the collectors is a beam that can rotate about pivots connected to support columns. The beam carries the mirror panels connected by mounting brackets. The mirror brackets also provide mounting points for the receivers. The beam is connected to a pulley, which is rotated by means of opposing cables connected to the tilt mechanism. A central column incorporates the tilt mechanism, essentially a trolley in track arrangement. As the tilt trolley translates it induces rotation of the beams through the cables and pulley. The collector is thus able to tilt through 180° to follow the sun. The trolley is moved by a linear actuator, which is propelled by a DC motor.

Sun tracking

A sun-tracking control system has been developed. The actuator position for the collectors is controlled by a single time based open loop microprocessor controller.