Climate Solutions Act of 2019 This bill establishes renewable energy standards, energy saving targets, and greenhouse gas emission reduction targets. Specifically, the Department of Energy (DOE) must promulgate regulations to increase the percentage of electricity sold in the United States that is generated from renewable sources. By 2035, 100% of electricity must be generated from renewable sources. DOE must also promulgate regulations that set cumulative energy savings targets for retail electric energy and natural gas suppliers. The savings must be achieved through energy efficiency improvements. For electric energy suppliers, the targets must increase from .25% of sales in 2020 to 1.5% of sales in 2025 and each year thereafter through 2030. For natural gas suppliers, the target must increase from .25% of sales in 2020 to .5% of sales in 2025 and each year thereafter through 2030. Each year's savings must be in addition to the previous years' savings. DOE must allow suppliers to achieve the targets through a market-based trading system. The Environmental Protection Agency (EPA) must promulgate annual emission reduction targets for each of 2030 through 2050 to ensure that U.S. greenhouse gas emissions (1) in 2035 are at least 40% below those in 1990, and (2) in 2050 are at least 80% below those in 1990. The EPA must promulgate final regulations to implement those targets within seven years and review them at least every five years thereafter.