Solar heaters are devices that use solar energy to heat water or air. There are several synonyms for solar heaters, including solar water heaters, solar hot water systems, solar thermal systems, and solar heating systems. These systems are becoming increasingly popular as people seek more energy-efficient and environmentally-friendly ways to heat their homes and water. Some countries even offer incentives and tax credits for the installation of solar heating systems. While the initial cost of installation can be costly, the long-term benefits of reduced energy bills and decreased carbon emissions make solar heaters a smart investment for homeowners.