Solar water heaters are an efficient and cost-saving solution for heating water using the sun's natural energy. These systems are especially popular in sunny regions and are ideal for both residential and commercial use. A typical system includes a solar collector—usually mounted on the roof—and an insulated storage tank. The collector captures sunlight and converts it into heat, which is transferred to the water in the tank. This method eliminates the need for conventional electric or gas heaters, helping users reduce energy bills while also protecting the environment by lowering carbon emissions. There are two main types of systems: passive and active. Passive systems rely on gravity and natural circulation of water. They are simple in design, more affordable, and require minimal maintenance. These systems are often suitable for smaller homes or areas where the water tank can be placed directly above the collector. Active systems, however, use small electric pumps and controllers to circulate water or a heat-transfer fluid between the collectors and the storage tank. This allows more flexible installation, better performance in cold weather, and improved energy efficiency for larger buildings or multistorey homes. Modern solar water heaters can also be equipped with backup electric heating elements to ensure hot water supply during cloudy or rainy days. The systems come in various sizes—ranging from 100 to 500 liters or more—depending on the daily water usage needs of the household or facility. For places like hostels, hotels, hospitals, and apartment buildings where hot water demand is high, larger and more advanced systems can be installed. With proper maintenance—such as occasional cleaning of the collector and checking for leaks or blockages—a solar water heater can last over 15 years. In the long run, investing in a solar water heater not only lowers your electricity bills but also adds value to your property and contributes to a greener planet.