In the renewable energy industry, technology development requires a large initial investment by firms and takes a long time. Thus, protecting patents in this industry has become an increasingly important issue in maintaining a company's value. In this study, we examine how patent protection affects firms' market value by analyzing the listed companies in South Korea in the renewable energy sector over a 35-year period (from 1980 to 2014). We find that simple patent counts are not a strong measure for explaining a firm's financial success in this industry, whereas indices that represent a firm's ability to protect patents (backward citation and patent family) positively and significantly affect the firm's market value. This study suggests that patent protection is an important factor for companies in improving their economic value in the renewable energy sector.