This work presents the thermodynamic analysis of a direct-expansion solar-assisted heat pump to provide domestic hot water. An aluminum bare collector/evaporator and a compressor that uses refrigerant R600a as working fluid compose the system. Boiling and condensation temperatures are -8 and 54.4 °C, respectively. The system test is conducted under different weather conditions (i.e. rainy, cloudy and clear day), obtaining a variation of the coefficient of performance between 4.07 and 6.72 for an average solar radiation in the range of 451.6 and 721.5 W·m-2. The water final temperature attains a value between 47.7 and 58.6 °C. The system works with solar energy, both thermal and photovoltaic, to replace conventional energy sources conducing to decrease the carbon reduction factor (CFC) in 89.5 % being lower than the 1977.2 kg of annual CO2 emissions produced by an electric shower.