Elizabeth Thomsen

Results from the first ANU-chromasun CPV-T microconcentrator prototype in Canberra

A first prototype of the hybrid CPV-T ANU-Chromasun micro-concentrator (MCT) has been installed at The Australian National University (ANU), Canberra, Australia. The results of electrical and thermal performance of the MCT system, including instantaneous and full-day monitoring, show that the combined efficiency of the system can exceed 70%. Over the span of a day, the average electrical efficiency was 8% and the average thermal efficiency was 60%.

Investigation of the Temperature Dependence of the Optical Properties of Thermal Transfer Fluids for Hybrid CPV-T Systems

This study investigates the influence of temperature on the spectral absorption characteristics of three heat transfer fluids; propylene glycol, mineral oil, and silicone oil. The region of interest of the liquid absorption spectra ranges from 700 to 2000 nm. The absorbance of propylene glycol was found to have a strong dependence on temperature. Mineral oil and silicone oil did not present significant temperature dependent absorbance. Absorbance peaks for water were found at 750, 985 1175, 1285 and 1680 nm. Propylene glycol also showed absorbance changes in these regions. In addition, propylene glycol displays two other regions of temperature-dependent absorbance. In contrast with silicone oil and mineral oil, the hydroxyl bond is only present in water and propylene glycol. It is thought that resonant absorption of the hydroxyl bond is responsible for the measured temperature-dependent absorption change.

Towards an innovative spectral-splitting hybrid PV-T micro-concentrator

A hybrid concentrator PV-Thermal (CPV-T) system for delivery of electricity and 150°C hot fluid in a structure suitable for roof-top installation on domestic, commercial, and industrial buildings is being developed by ANU in collaboration with the University of New South Wales, CSIRO, and industry partners. A first design based on beam-splitting utilising liquid-absorption filters is being analysed, with a study of the most suitable candidate fluids. An initial selection of four liquids was conducted; with the liquids subjected to accelerated tests to analyse their long-term performance and possible optical and chemical degradation. Some of the fluids showed optical changes after high temperature test and UV exposure, leading to slight yellowing.

Flexible sliver modules

This paper presents the design, fabrication, testing, and integration with equipment of a flexible photovoltaic module. The modules are based on mono-crystalline silicon Sliver cells. Tests have been developed to specifically test flexible modules, including their flexibility, abrasion resistance, power to weight ratio, and partial shading. The results of a 0.1 m2 module with 13 W power output and 178 W/kg are presented.

Materials and manufacturing processes for high-efficiency flexible photovoltaic modules

An overview of the materials, processing techniques, and characterisation procedures for flexible solar modules is presented. Flexible modules are lightweight, roll-able, and/or foldable for storage and transport. The design approach selected by the Australian National University incorporates very thin, high-efficiency crystalline silicon solar cells embedded between flexible coversheets, and supported by silicone encapsulant and flexible electrical contacts. The modules can be fabricated using a number of approaches including constructing the circuitry separately to the packaging, or using the packaging as both a protective layer and a base for circuitry.

Evaluation Of Electrical And Thermal Performance Of A Linear Hybrid CPV‐T Micro‐Concentrator System

Chromasun Inc. and The Australian National University have developed a low‐concentration, linear, hybrid micro‐concentrator (MCT) system suitable for urban rooftop installation. The system produces both electrical and thermal power, integrating the functionality of separate flat plate photovoltaic and solar hot water systems. The MCT system utilises industry‐standard components, including modified mono‐crystalline silicon one‐sun solar cells, commonly used in flat panel applications. The MCT manufacturing processes are designed around low‐cost methods, and tap directly into existing economies of scale. Initial test results without any system optimisation has demonstrated an electrical output of more than 300 W, and a thermal output of more than 1500 W at 950 W/m2 DNI.

Four Terminal, Reflective Tandem Cells for Silicon Efficiency Greater than 30%

Tandem cell approaches offer the opportu nity to increase silicon cell efficiency. Four ter minal approaches provide the flexibility to freely choose th bandgap of the top cell without compromising t he system efficiency. By using the top cell as a reflector o f sub-bandgap light, a simple tandem approach has b een demonstrated that has the potential for strong syst em efficiencies. Efficiency of 27.8% was achieved in a system comprising a 24.6% GaAs top cell and 20.3% bottom c ell. Improvements in either the GaAs cell or the S i cell could increase efficiency beyond 30% with combined improv ements leading to a realistic potential of 34%. Com bination with single axis roll trackers offers potential for reflective tandems to be practicable.

A general purpose characterization system for rooftop hybrid microconcentrators

A versatile characterization system for hybrid thermal and photovoltaic solar receivers is presented and demonstrated. The characterization of the thermal loss and effective area of a novel hybrid receiver is presented.

Hybrid CPV-T micro-concentrator system

A hybrid CPV-Thermal (CPV-T) micro-concentrator (MCT) system has been constructed. The MCT is a fully sealed, light-weight structure with a low wind-load factor. It incorporates modified one-sun solar cells operating at around 15 suns optical concentration using a novel ultra-lightweight Fresnel array with closed loop tracking to produce electricity and thermal energy suitable for generating hot water or running absorption chillers. Preliminary electrical and thermal performance data will be presented.