###### Abstract  
Countries differ in terms of their socio-economic development, population growth, and energy consumption. Many countries still depend on conventional energy to supply enough energy source for their demand, while some have made considerable progress in making the transition to renewable/sustainable energy sources. Owing to the increasing demand and drawbacks of conventional energy sources, policies can play a major role in encouraging and increasing the uptake of renewable energy (RE) technologies. In this paper, a general overview on the RE activities in the three leading countries--China, Brazil, and the United States of America (USA)--is presented. Moreover, a comparative analysis on the implementations of the RE support policies is conducted. The linear regression analysis technique is applied to develop several models for the three countries in order to investigate the effect of different policies on RE. The main contributions of this study are establishing a link between RE support policies and RE development (in terms of the installed capacity) in the three countries under study, and providing models that can be used in estimating RE development using RE policy data. In addition to this, some models are developed to investigate the relationship between RE installed capacity and the patents. The linear regression analyses suggest that RE policies promote the development of RE installed capacity in the three countries in different proportions. For example, it is found that each additional wind policy will increase the RE wind capacity in China, Brazil, and the USA by 1.63, 0.689, and 1.576 GW, respectively. Moreover, the economic instruments turn out to be more effective in promoting the RE installed capacity in the USA and Brazil, while the policy support and regulatory instruments are the most influential policy categories in China. Furthermore, the linear regression analyses indicate the existence of a positive significant relation between the number of patents and the total RE installed capacity in the three countries. development; renewable energy; patents; policies; linear regression 20202026 October 202 national and state-level policies play major roles in effective RE deployment and promotion due to the cost disadvantage of RE compared to conventional energy sources. According to [PERSON] et al. (2017) and [PERSON] (2018), the lack of governmental policies is a seriously limiting factor for the development of RE globally. Although not all the countries currently have RE policies, there are many countries in the world which have adopted various RE support policies. These policies include economic instruments such as fiscal and financial incentives, policy support related to strategy planning, and regulatory measures. Among these policies, feed-in tariffs (FITs), renewable portfolio standards (RPS), and quotas are the most widely adopted ones. FIT, RPS, and quota policies are applied globally at either state/provincial or national levels. [PERSON] et al. (2017) demonstrated that governments have also started introducing more FITs in cities. Especially in the last few decades, the electricity sector has been experiencing a period of fast deployment of RE generation technologies. Since 2012, new global RE capacity additions have accounted for more than half of new power capacity additions. International Renewable Energy Agency (IRENA) (2018) stated that, at the end of 2017, the total RE power capacity exceeded 2178 GW, indicating that it had more than doubled within nine years. It also indicated that the new global capacity additions of renewables in 2017 reached almost 167 GW, including a combined 1 GW from concentrating solar power (CSP), geothermal, and marine energy; 22 GW of hydropower; 93 GW of photovoltaic (PV); 46 GW of wind power; and 5 GW of bioenergy. According to (2018), the top countries for total installed renewable capacity at the end of 2017 were China, the USA, Brazil, Germany, India, and Canada, respectively.