The study posed a research question: did the situation caused by COVID-19 affect the economic position of energy companies? The aim of the study is to investigate the impact of the situation of the epidemic state introduced in 2020 on the activities of the efficiency of energy sector companies. The subject of the research will be the ten largest Polish power plants in terms of electricity production, including four capital groups to which they belong. Financial data from 2014 to 2020 will be used for the research. To test the effectiveness, the tools of the ratio analysis will be used. The analysis of the financial statements in terms of investments in manufacturing activities confirms the hypothesis that companies investing in new solutions and technologies will be best prepared for an exceptional situation. The results of the research show that those capital groups which in the period preceding the outbreak of the epidemic made the largest investment outlays and at the same time their financial ratios and market valuation on the Warsaw Stock Exchange were the highest, they also achieved the highest financial results during the pandemic—they had the most favorable economic situation.