a combined heat and power solar concentrating collector joe coventry centre for sustainable energy...

A combined heat and power solar concentrating collector

Joe Coventry

Centre for Sustainable Energy Systems

Australian National University

The CHAPS collector

Combined Heat And Power Solar Collector

Generation of DC electricity AND Generation of hot water

Applications: • DHW, HHW and electricity• Commercial buildings• Light industrial buildings• Residential colleges

(eg. Bruce Hall 300m2 system)

CHAPS system components

CHAPS troughs• 24 m long x 1.6 m wide rows• 37x geometric

concentration ratio• Modular system

Solar cells• 20% efficient under 30suns

and 25°C• Low series resistance• Manufactured at ANU

CHAPS system componentsReceivers

• Aluminium extrusion• Series connected solar cells• Finned fluid conduit• Glasswool insulation• Anti-freeze, anti-corrosive heat

transfer fluid• Assembled at ANU

Mirrors• Glass-on-metal laminate mirrors• Silver backed mirror• Stamped tab ribs• Manufactured at ANU

Efficiency tests

Measured on a custom built outdoor test rig at ANU with:• 1.25 m wide trough• 27 solar cell receiver• Steady state conditions• Maximum power point electrical load• Range of input temperatures• Constant low flow conditions

Efficiency results include:• Losses due to receiver shading• Losses due to hydraulic connections

Efficiency Results

Flux profile across a cell

Illumination profile• measured using videographic

flux mapping techniques• Peaks exceeding 100 suns• Significant temperature

variation across cells

Cells & Modules – testing

Range of cell and module tests• UV testing• High temperature testing• Humidity testing• Thermal cycling• On sun!

Challenges• Differential expansion• Corrosion• Water ingress

Receiver design

Domestic system• Mechanical bond• Adhesives• Intermetalic bond• Electroplating

Commercial system• Closed circuit

Attaching the cells

Thermal tape Alumina based substrates Anodising Plasma coating

Interconnections

Tabs Tab connections• Braid• Shim• Spot welding

Optical system

GOML mirror Low iron glass Silicone Textured cells

Electrical13%

Thermal63%

Reflection from cells7%

Insulation losses3%

Convection losses1%

Radiation losses1%

Reflection from receiver4%

Mirror shape error2%

Absorption in mirror6%

Conclusions

Significant work on reliability, longevity CHAPS systems beginning to be commercialised