Nowadays, climate change and energy consumption have been one of the global agendas, wherein, the building energy use has a significant contribution with one-fifth total worldwide energy. Therefore, the awareness of building designing with high energy efficiency and renewable power technologies need to be promoted. For hot climate regions, the high solar radiation is appropriate for solar technologies to be integrated in buildings. BIPV is a technology of combining photovoltaic on building fabric and contribute to overall energy efficiency caused by electricity generation, solar heat gain effects. This study investigated impact of BIPV system on indoor environment such as building temperature and energy load in Vietnamese tropical climate. First, three options of photovoltaics heat transfer modes offered in EnergyPlus software and effect of air gap on indoor temperature are considered with a simple simulation. Second, a model of an existing typical townhouse in Vietnam with different types of BIPV on roof was modeled as cases of study. The indoor energy loads as well as photovoltaics efficiency were compared. Possibility of reaching net zero energy building was investigated. Finally, cases of BIPV was analysis in life cycle cost to find out the best solution for investment.