Design and Testing of a Low-Cost Solar Water Heater Using Recycled Materials

Abstract

Solar energy is an abundant, renewable, and environmentally benign source of electricity that has been used for a variety of purposes throughout human history.  Among its various applications, solar water heating is one of the most practical and cost-effective ways to transform solar radiation into usable thermal energy.  Solar water heaters (SWHs) absorb sunlight and turn it into heat for a variety of home, industrial, and agricultural purposes, including bathing, washing, cleaning, and space heating.  Solar water heaters, as opposed to traditional water heaters that use electricity or fossil fuels, save energy, reduce reliance on non-renewable resources, and reduce environmental pollution.

The essential idea of solar water heating is the conversion of solar energy into thermal energy via collectors.  These collectors capture solar energy and convert it to a fluid, often water or a heat transfer medium, which circulates through pipes or tubes.  The hot fluid is kept in an insulated tank for subsequent use.  Depending on the design, climatic conditions, and economic variables, SWHs can be passive or active.  Passive systems rely on natural convection and do not require pumps or controllers, whereas active systems employ pumps and controls to circulate fluids and regulate temperatures.

Despite the scientific maturity of solar water heating, various challenges prevent widespread adoption, particularly in rural and low-income regions.  High initial costs, difficult installation processes, and a lack of knowledge are major deterrents.