U.S. Department of Energy - Energy Efficiency and Renewable Energy

Solar Energy Technologies Program

Solar Heating Advanced Applications

A transpired-air collector absorbs solar energy, providing heated ventilation air to the BigHorn Home Improvement Center in Silverthorn, Colorado. (Credit: Jim Yost)

Several advanced concepts in solar thermal energy show promise for future markets. Research and development efforts sponsored by DOE could lead to cost-competitive energy options for several applications.

Currently, the National Renewable Energy Laboratory's (NREL) research is focused on reducing the cost of using solar technology to generate domestic hot water in cold climates. The best opportunities lie in reducing cost of "non-collector" components, such as tanks, heat exchangers, pipes, and valves. components NREL's multi-year technical plan for solar research addresses other solar thermal applications, such as solar space heating and solar cooling, after cold climate water heating is substantially finished. Additional technologies that have some potential market niches include water disinfection or desalination. Market viability of both these technologies depends on the development of very-low-cost solar collectors.

The Sandia National Laboratory (SNL) Advanced Manufacturing Center works with manufacturers of solar-thermal and other related products on technical issues involving product realization. This includes product concept, design prototyping, testing, manufacturing processes, production, field evaluation, and disposal. Based at SNL, the Technology Assistance Program assists manufacturers in reducing the cost and improving the reliability of their products. It also helps suggest solar thermal technologies for specific applications and needs.

Low-Cost Solar Water Heating

Laboratory researchers and other experts see great potential for constructing solar water-heating systems with lower-cost polymer materials. Polymers could replace or reduce the need for glass, copper, and steel in the collectors and the piping. In the past, some polymer glazings discolored and failed as a result of exposure to ultraviolet solar radiation. To overcome these challenges, researchers are examining the durability of thin films and other polymer components and are working with industry manufacturers and university research teams to develop and test field-scale prototypes. Two industry teams have been developing the products designed for mild climates that are scheduled to enter the market in limited numbers in 2006.

Collectors for Crop Drying

Transpired-air collectors have been successfully used to preheat building ventilation air. These collectors are also applicable to other commercial uses, such as crop drying. Solar heat is often the preferable choice for crop drying because this type of heating does not burn or harm delicate foods, which often occurs when using steam or burning fuels. The potential international market for low-cost transpired-air collectors is great, especially in developing countries where vast quantities of coffee, grains, fruits, vegetables, and other crops are harvested and dried and when conventional fuels are expensive or unavailable. This market becomes more viable as costs of natural gas and propane product increase.

Currently, the National Renewable Energy Laboratory's (NREL) research is focused on reducing the cost of using solar technology to generate domestic hot water in cold climates. NREL's multi-year technical plan for solar research will address other solar thermal applications, such as solar space heating and solar cooling. Additional technologies that have some potential market niches include water disinfection or desalination. Market viability of both these technologies depends on the development of very-low-cost solar collectors.