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