The present study experimentally investigated the thermal efficiency, collector area, weight, embodied energy, environmental CO₂ emissions of Al₂O₃/water nanofluid flow in a flat-plate solar collector and with coiled wire turbulators. The experiments were performed at  that is equal to 0.1%, 0.2% and 0.3% and volume flow rate from 120 to 300 L/h. Results indicate that the collector thermal efficiency increased with the increase of particle volume loadings and volume flow rates. The thermal efficiency of the collector with water circulate is 53%, whereas it is enhanced to 65% at  = 0.3% nanofluid, and it is further enhanced to 77% for  = 0.3% nanofluid with 10-mm coiled wire insert in a collector tube at a volume flow rate of 300 L/h. The collector area is declined to 8.66% ( = 0.1%), 14% ( = 0.2%) and 18.66% ( = 0.3%) for nanofluids. The collector area is further reduced to 31.33% for  = 0.3% nanofluid and with a …