As the country with abundant geothermal energy resources, Indonesia has the opportunity to allocate geothermal as the leading renewable energy to substitute dependency on oil and gas. However, there are some challenges that developers faced in terms of technical, financial, and political challenges. Thus, making geothermal projects less attractive for investors to invest in this energy sector. Notably, the financial challenge that will be close attention for private sectors to tackle. Feasible financing is needed to tackle this issue to attract more investors. This paper aims to analyze the feasibility of a geothermal project in Lumut Balai geothermal power plant by formulating the optimal and efficient financial modeling and performing a probabilistic approach using Monte Carlo simulation. In this regard, the impact of feed-in-tariff will be assessed through three scenarios that will be simulated in the model. The results indicate that feed-in-tariff plays a significant role in determining the attractiveness of a geothermal project in Indonesia.