In Japan, it is anticipated that renewable energy will account for up to 38% of total electricity generation by the fiscal year 2030. Among renewable energy sources, particularly the adoption of photovoltaic power is advancing. However, due to constraints such as supply–demand balance constraints and transmission capacity constraints, output control measures are often implemented to temporarily halt photovoltaic power generation before exceeding the constraint limits. This situation may pose obstacles to the future proliferation of renewable energy. On the other hand, Japan still heavily relies on thermal power generation, with the risk of being heavily impacted by the soaring prices of imported fossil fuels like LNG. Therefore, this study aims to analyze the impact of photovoltaic power and thermal power generation on electricity prices, referred to as area prices, to provide recommendations for future energy policies aimed at stabilizing electricity prices. Specifically, using the propensity score matching method, this research analyzes the influence of the proportion of photovoltaic power and thermal power generation on area prices within the Tokyo Electric Power Grid area.