Monocrystalline laser-grooved solar cells
Object No. 91/2086
The laser grooved solar cells made at the University of New South Wales (UNSW) were the first to have their metal contacts buried below the surface, leaving more area free to capture energy from the sun. This innovation increased the cells' efficiency (the proportion of the incident energy converted to electricity) relative to cells of similar basic type. Increasing efficiency is a major aim of solar research, as it is one way to improve the economics of using solar energy. The first solar (photovoltaic) cells, made in 1953, were 4% efficient. Professor Martin Green began carrying out photovoltaic research at UNSW in 1975, and his team had a series of world firsts, including the first 20% efficient cell (monocrystalline silicon laser grooved) in 1985. In 1990 they announced that their PERL cell was 24% efficient. It was Professor Stuart Wenham, Green's chief co-worker, who conceived the idea of laser grooving. Green and Wenham have advanced theoretical understanding of solar energy capture, developed a range of new technologies, solved many mass-production problems, and trained researchers and production engineers from around the world. The laser grooved solar cell was successfully commercialised and has helped the solar industry grow at a rapid pace. To make a commercial module or panel, many cells are electrically connected, covered with a sheet of low-iron glass and sealed in a robust frame. Modules produce direct current electricity (DC). For use with normal domestic appliances, or for export to the electricity grid, a group of modules must be connected to an inverter, which converts DC to alternating current (AC). These solar cells are made from monocrystalline silicon. They are more expensive to produce, but more efficient, than polycrystalline silicon cells. The economics of a solar installation depends on the capital cost of the modules and inverter, the labour and wiring costs, the orientation of the modules, and the number of hours of sunshine in the locality, as well as on efficiency. The efficiency of solar cells cannot be compared with the efficiency of power generated by burning fossil fuel, as sunshine is free and capturing it does no harm to the environment. Debbie Rudder, Curator, 2012
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Summary
Object Statement
Solar cells (2), with container, monocrystalline silicon, laser grooved buried contact, silicon / metal / plastic, Professor Martin Green / Dr Stuart Wenham, University of New South Wales, Kensington, New South Wales, Australia, 1987
Physical Description
Each cell is a dark grey square of boron-doped silicon, 400 micrometres thick, with 28 equally spaced fine metal strips (electrical contacts) in laser-cut grooves on the top surface parallel to one edge, and three equally spaced metal strips perpendicular to that edge. The contacts are made of nickel, copper or silver. The rear surface of the cell is also an electrical contact made of metal.
PRODUCTION
Notes
The cells were made in the Centre for Photovoltaic Devices and Systems laboratory at the University of New South Wales in the eastern Sydney suburb of Kensington in 1987. A cylindrical crystal of pure silicon doped with boron (to create vacancies in the atomic structure of the silicon) was grown in the laboratory using the Czochralski process. To make each cell, a wafer was sliced from the crystal, a laser was used to cut grooves in one surface, it was exposed to phosphorus vapour (to form a layer of electronic-rich silicon on the surface), the metal contacts and an anti-reflection coating were applied, and the cell was cut from the wafer. The cells were part of a research and development program, led by Professor Martin Green, aimed at improving the economics of solar energy by increasing solar cell efficiency and reducing manufacturing costs. Stuart Wenham and Martin Green received an Australian patent for the laser grooved solar cell in 1984, and they later patented a series of improvements in the technology.
HISTORY
Notes
The cells were tested at the Centre for Photovoltaic Devices and Systems before being donated to the Museum.
SOURCE
Credit Line
Gift of Centre For Photovoltaic Devices And Systems, 1991
Acquisition Date
20 December 1991
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