Solar energy technologies are increasingly being considered in providing efficient energy solutions for a wide variety of applications to generate electricity and heat. High rewarding rates at different levels were registered for both solar energy systems; solar thermal systems (ST) and photovoltaics (PV). The exploitation of the solar energy is dependent on the resource availability and local conditions in each region. Therefore, this paper presents a study conducted in the city of Guimarães in north Portugal. It aims at evaluating the energy efficiency of various types of both PV and ST systems existing in the market. The study carries out a comparative analysis of both photovoltaic modules and solar thermal collectors, as systems that are usually implemented to cogenerate the energy demand for electricity and sanitary hot water respectively at a domestic scale. The embodied energy in both systems and their components will be estimated basing on literature review and following the model “from cradle to gate” that considers the life-cycle phases during the manufacturing process. The produced energy by each of the systems will be estimated in this study using the simulation Portuguese software SCE.ER. The results show the estimated values of energy pay-back time of each of the examined photovoltaics and solar collectors systems.