Performance of the CHAPS Collectors

The performance of the Combined Heat and Power Solar (CHAPS) collectors at the Australian National University is described. Results from testing of the collector under steady state conditions at a range of input temperatures are presented. Measured results under typical operating conditions show thermal efficiency around 57% and electrical efficiency around 11%, and therefore a combined efficiency of 68%. An energy balance for the CHAPS collector is carried out, showing the relative significance of optical and thermal losses. The thermal performance of the collector is examined in detail, using temperature measurements within the receiver and at the glass surface. The transmission and absorption properties of the cover materials across the solar spectrum are examined using a spectrophotometer. Using these results, the temperature profile of the receiver is modelled using the finite element package Strand7. The results are discussed, and in particular, methods suggested for reducing the large temperature gradient between the centre and outside edges of the solar cells.