The energy sector has a vital role in climate change mitigation. In Brazil, the electricity generation sector is strongly dependent on hydropower generation, but thermoelectricity contribution has increased leading to a more carbon-intensive electricity mix. This trend will be aggravated with the expected significant increase in the electricity demand until 2050 and with the potential limitation of hydropower generation expansion due to environmental constraints. The extent of the role of solar power to overcome these challenges in the future has been hidden by energy modelling assumptions. A review on how solar energy has been considered in different models, was performed. The research further assessed the relevance of assumptions by developing an optimization model to explore the cost-effectiveness of solar electricity large-scale deployment up to 2050. The work found that most published solar energy assessments based on long-term energy modelling for Brazil currently are not updated regarding several assumptions, leading to models results where solar appears with a marginal role. The energy modeling exercise shows solar PV is cost-effective for Brazil, providing more than 36% of total electricity in 2050. This is a different conclusion from the energy and power modeling exercises conducted until now, where solar deployment has been underestimated. (C) 2020 Elsevier Ltd. All rights reserved.