PURPA Modernization Act of 2019 This bill addresses the Federal Energy Regulatory Commission's (FERC) one-mile rule and the mandatory purchase obligation for electric utility companies to purchase energy from certain facilities. The bill directs FERC to publish a final rule that allows any person or entity to provide a rebuttable presumption to the one-mile rule. Under the one-mile rule, facilities are considered to be located at the same site as the facility for which qualification is sought if they are located within one mile of such facility. Specified factors must be taken into consideration by FERC when it determines whether two facilities are located at the same site. The bill authorizes an electric utility company to waive the mandatory purchase obligation if additional power is not required to meet customers' electricity needs.