Design of a prototype spectrum-splitting concentrated

photovoltaics module Nathan Tam Supervisor: Professor Martin Green, Co-Supervisor: Dr. Mark Keevers

Theme: Resources and Infrastructure for the Future

Background and Overall Goals •A spectrum-splitting ‘power cube’ receiver (Fig. 1) that uses both silicon and triple junction (TJ) cells could

improve the efficiency of a concentrated photovoltaics (CPV) power tower (Fig. 2)

• This project aims to prove the benefits of spectrum-splitting by fabricating and testing a prototype spectrum-

splitting CPV module, with a target efficiency of 40%.

• The optical design (Fig. 3) has been finalised thanks to a collaborative effort with Raygen Resources. Fig. 4

shows the spectral responses of the prototype’s optical elements, as compared with the solar spectrum.

• The next step of the project has been to realise the optical design with commercial opto-mechanical

components.

Aim • To develop the mechanical design of a prototype spectrum-splitting CPV module that is mountable on a sun-tracker

Must consider robustness, portability, weight, and adjustability

• Select the components that are most suitable for the module prototype

Conclusion and Future Plans • The mechanical design of the prototype module has been finalised

it was concluded that the translation and rotation stages in the First Iteration were

too heavy and not robust enough

the design goals were met by prioritising robustness, light weight, and adjustability

over the precision of the stages in the First Iteration

• The next step for the project is to order the components and fabricate the prototype module

when the prototype has been built, testing can begin

the project will be continued over the course of 2013 as undergraduate thesis work

• Upon completion, the project will provide realistic cost and performance estimates for a full-

scale system that uses this approach

Method • Performing a detailed analysis of components and catalogues

comparing components with required functionality based on design goals, confirming compatibility

• Corresponding with supplier representatives; building and maintaining a rapport

Fig. 1: Power Cube receiver

Results

1.5m Optical Rail Rail Carriages

8” Mirror

Mount

8” Parabolic Mirror

Goniometer

Rotation Stage

300x300mm

Breadboard

X-axis

Translation

Stage

Vertical

Translation

Stage

Translation

Stage

300x300mm

Breadboard

Rotation

Stage

Filter and Mounting Post

TJ Cell Assembly

Translation Stage

Rotation Stage

150x150mm

Breadboard

Rotation

Stage Translation

Stage

Si Cell

Assembly

Spacer

Block

First Iteration

1m Optical Rail Rail Carriages

8” Mirror

Mount

8” Parabolic Mirror

Rotation Stage

150x300mm

Breadboard

Spacer Post

Post

Platform

Fine Vertical

Adjust Collar

75mm

Post

150x300mm

Breadboard

Filter and Mounting Post

TJ Cell Assembly

Translation Stage

Rotation Stage

Rotation

Stage Translation

Stage

Si Cell

Assembly

Spacer Post

300x300mm

Breadboard

Final Design

Total Cost Total Weight (kg)

$8,061.54 38.4

Total Cost Total Weight (kg)

$5,185.68 28.4

Fig. 2: Solar Systems CPV power tower (Bridgewater, VIC)

Hollow

reflectors

Dichroic filter

Parabolic

mirror

Si cell

assembly

TJ cell

assembly

Fig. 3: Ray-trace diagram showing optical design of prototype

Fig. 4: Use of a spectrum-splitting filter to better utilise the solar spectrum

Silicon Cell

TJ Top Cell

Solar Spectrum

TJ Middle Cell

Filter Transmission TJ Bottom Cell