Distributed Energy Demonstration Act of 2019 This bill establishes several renewable energy and energy efficiency grant programs. Specifically, the bill requires the Department of Energy (DOE) to establish grant programs for advancing the integration and optimization of distributed energy resources (e.g., smaller power sources that can be aggregated to provide power, such as rooftop solar panels) into the electric energy grid; demonstrating the use of household hot water heaters as energy storage resources; advancing electric vehicle technologies; and supporting the voluntary deployment of granular electricity pricing that is based upon the electricity's value at the time and location of the production or consumption of the electricity. In addition, the bill reauthorizes through FY2025 and revises the DOE grant program for smart grid investments.