This study observes the impact of penetration and calculates the maximum penetration of variable renewable energy (VRE) power plants in the Java–Bali power grid for the 2019–2023 period, especially for solar power plants. Solar power plant penetration mapping for the Java–Bali grid in to some area must also be carried out, due to the existing system’s limited technical capabilities. Variables used to determine VRE’s maximum penetration are properties of thermal generating units, such as ramping capability, technical minimum load, and primary energy conversion mechanism. Net load profile aggregation between VRE and existing thermal generating units is used to analyze the degree of VRE penetration. Then, the aggregate system ramping capability and system technical minimum load are evaluated. The results show that VRE penetration at a capacity of 5,000 MWp increases the grid’s ramping requirement. In 2023, the maximum allowable penetration of VRE’s capacity in the Java–Bali system is 5.85%, with a total installed capacity of 6,447 MWp for solar power plants and a peak load of 36,669 MW. The strongest penetration is in the Paiton–Grati subsystem, with a total installed capacity of 711 MWp.