Faculty of Engineering School of Photovoltaic and Renewable Energy Engineering

Space Photovoltaic Solar Cells

10th July 2018 3rd CubeSat Innovation Workshop

N.J.Ekins-Daukes

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• 1367W/m2 in Earth Orbit.

• <1000W/m2 at Earth’s surface.

Silicon Space Solar Cell

!3N.Fatemi et al., “Solar Array Trades Between Very High-Efficiency Multi-Junction and Si Space Solar Cells”, Proc. IEEE PVSC, p1083 (2000)

AzurSpace S32

Weight : 32mg/cm2 Efficiency : 16.9% (BOL) Specific Power : 0.71W/g (BOL) Power density : 229 W.m-2 (BOL) 149 W.m-2 (EOL)

Multi-Junction Solar Cell : Concept

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Y

X

Ge

Load

1

2

3

1 2 3

Triple Junction Solar Cell : InGaP/GaAs/Ge

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Triple Junction Solar Cell

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AzurSpace 3G30C

Weight : 50mg/cm2 Efficiency : 29.8% (BOL) Specific Power : 0.81 W/g (BOL) Power density : 403 W.m-2 (BOL) 365 W.m-2 (EOL)

Inverted Metamorphic Triple Junction Solar Cell

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IMM 3J solar cell (Sharp Corp.)

Weight : 25mg/cm2 Efficiency : 32.3% (BOL) Specific Power : 1.75W/g (BOL) Power density : 437W.m2 (BOL)

(Data from SolAero)

Inverted Metamorphic MJ Cells

Lattice parameter

Microlink Devices Inc.

Airbus Zephyr

Space PV Research @ UNSW : Interstitial Light Trapping

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A. Mellor, N. P. Hylton, S. A. Maier, and N. J. Ekins-Daukes, Sol Energy Mat. Sol. C., vol. 159, pp. 212–218, 2017. & Patent No. WO 2017/208006

Ongoing funding :US-Air Force / AOARD

Seed funding:

Space PV Research @ UNSW : 4+J solar cells & beyond..

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Molecular Beam Epitaxy @ ANFF-NSW

A/Prof. Stephen Bremner

GaAsBi

4+ junctions will enable efficiencies above 33%.

Semiconductor materials with band-gaps between 1.2-0.9eV required.

Summary

• Silicon PV is now a legacy technology: low efficiency and poor radiation tolerance.

• III-V Multi-junction technology is now standard on all commercial satellites

• 30% BOL efficiency is now routine • 32% BOL efficiency possible with IMM

technology • Research opportunities at UNSW:

• Highly radiation tolerant photovoltaic solar cells.

• >33% BOL next generation space solar cells: new low band-gap semiconductor materials to enable 4+ junction cells.

• Radiation induced defects in space solar cells (theory & experiment)

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Sharp Corp.

AzurSpace

Questions?

Ned Ekins-Daukes

nekins@unsw.edu.au