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2016/46/1 Photovoltaic mini-module, 'Spectrum Splitting Prism', glass / silicon cell / triple-junction cell, designed and made by the Australian Centre for Advanced Photovoltaics, University of New South Wales, Sydney, New South Wales, Australia, 2014-2016. Click to enlarge.

Spectrum Splitting Solar Cell Prototype

Made 2016
This spectrum splitting solar cell, developed at the Centre for Advanced Photovoltaics at UNSW, represents a major innovation in rooftop solar cell design. In 2014 it broke the world record achieving over 40% efficiency from natural sunlight. It is a unique approach to improving rooftop solar efficiency focusing on a solar module design that can be applied to existing technology. The team is hoping to establish the design's feasibility by 2020. If successful they will look at combining cheaper silicon cells with other affordable cell technology to bring the cost of the module down.

Spectrum splitting, which involves using a combination of different technologies to extract energy from different wavelengths of sunlight, is occurring around the world. It most commonly involves splitting the energy between a photovoltaic array and a thermal (heat) system. Researchers are also looking at splitting between two solar cells for concentrator photovoltaics (for solar farming).

This project is unique as it looks at using unfocused direct sunlight (one sun) and applying the design to rooftop application.


Object No.


Object Statement

Photovoltaic mini-module, 'Spectrum Splitting Prism', glass / silicon cell / triple-junction cell, designed and made by the Australian Centre for Advanced Photovoltaics, University of New South Wales, Sydney, New South Wales, Australia, 2014-2016

Physical Description

Glass triangular prism of high grade silica bonded to two solar cells. Attached to the base is a triple-junction cell of indium-gallium-phosphide; indium-gallium-arsenide; and germanium. The triple-junction cell has a deposited filter on the surface that reflects infra-red light. Attached perpendicular (90 degree) is a single junction silicon cell. Each solar cell has two metal ribbons coming from the positive and negative terminals of the cells. An anti-reflection coating has been applied to the longest rectangular face of the prism.



37 mm


126 mm





This solar mini module was designed by Dr Mark Keevers and Professor Martin Green. The prototype was made by Dr Keevers in his laboratory at University of New South Wales, Sydney, Australia between 2014 and 2016. It is one of a number of mini-modules produced throughout this period. The mini-module combines a silicon cell on one face of a glass prism (high grade silica) with a triple junction cell on the other. Between the prism and the triple-junction cell is a specially designed and deposited filter.

The silicon cell is produced by Trina Solar and the triple junction cell by AZUR SPACE Solar Power GmbH. The filter was designed by American company Omega Optical to the UNSW team's specifications and deposited onto the triple junction cell. The glass prism was manufactured by Australian company Longman Optical.

The triple junction cell has a top layer of indium-gallium-phosphide bonded to a middle layer of indium-gallium-arsenide sitting on a substrate of germanium. Each layer is grown on top of the previous layer.



The concept for spectrum splitting evolved out of work on upgrading photovoltaic receivers in a concentrator system. Professor Green and Dr Keevers developed a concept called the ?Power Cube' which utilised a prism shaped receiver. The concentrator system was a solar tower being developed by Australia's RayGen Resources. It uses a field of mirrors to concentrate light on a one square meter solar module receiver. This system placed a filter over the silicon array that lets only a small part of the light spectrum through. The rest of the light is reflected down to a triple junction cell array.

When they tested their design in 2014 they achieved over 40% efficiency (taking all losses into consideration). Due to the success of that project they were asked by ARENA to continue their work and design a ?one sun' version (using natural sunlight). The ?Spectrum Splitting Prism' is the result of this work.

This module was developed using expensive triple-junction cells, which have been developed for space exploration. The cells were modified by the company Azure for use on solar vehicles in the World Solar Challenge.


Credit Line

Donated by the School of Photovoltaic and Renewable Energy Engineering (SPREE). This minimodule was fabricated as part of the Power Cube project, funded by ARENA (Australian Renewable Energy Agency), UNSW, NREL (National Renewable Energy Laboratory) and RayGen Resources Pty Ltd.

Acquisition Date

11 November 2016

Cite this Object


Spectrum Splitting Solar Cell Prototype 2019, Museum of Applied Arts & Sciences, accessed 28 May 2020, <>


{{cite web |url= |title=Spectrum Splitting Solar Cell Prototype |author=Museum of Applied Arts & Sciences |access-date=28 May 2020 |publisher=Museum of Applied Arts & Sciences, Australia}}
This object is currently on display in Experimentations at the Powerhouse Museum.

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