One embodiment can provide a photovoltaic roof tile module. The photovoltaic roof tile module can include a front cover, a back cover assembly, photovoltaic structures positioned between the front cover and back cover assembly, and an internal circuit component electrically coupled to the photovoltaic structures. The internal circuit component is positioned between the front cover and the back cover assembly. The back cover assembly can include at least one through hole and a metallic plug inserted inside the through hole. A first surface of the metallic plug can electrically couple to the internal circuit component, and a second opposite surface of the metallic plug can be exposed to surroundings external to the photovoltaic roof tile module, thereby facilitating electrical coupling between the photovoltaic roof tile module and another photovoltaic roof tile module.