This study reviewed how the changes of the government policy on solar power generation projects affected the annual mandatory quotas of the regulated power providers under the RPS (renewable portfolio standard) system and analysed economic feasibility of the investment for meeting their quotas as compared to the case of non-regulated power providers. The analysis results showed that under the discount rate of 7.5%, which was used for the annual national electricity plans for the recent years, both the regulated and non-regulated power providers achieved economic feasibility under both the NPV (net present value) method and the real option pricing method. It was also shown that higher profitability was attained by non-regulated power providers than by their regulated counterparts, which can be attributable to the fact that regulated providers are required to out-source 50% of the total quota. The results of this study are considered to be useful for establishing a meaningful mid term or long term strategy for the future of solar power generation linked to the current RPS system.