A solar water heater's efficiency is evaluated in various ways, making it crucial to understand the various metrics before investing in or purchasing one. The primary goal of a solar water heater is to convert sunlight into heat energy, which is then used to warm water for household purposes.
The most widely used method of rating solar water heaters is based on their thermal efficiency, which typically falls between 50 to 90 percent. Thermal efficiency refers to the system's ability to convert the sun's energy into usable heating. This percentage is usually denoted as a 'collector efficiency' since it gauges how efficiently the solar collector is able to capture and transfer heat from the sun to water. Some manufacturers provide better efficiency performances by focusing on better heat transfer, effective insulation, and reduced heat loss during transfer and circulation methods.