Wavelength-selective surfaces for solar energy utilization can be divided into two classes: selective-black absorbers and transparent heat mirrors. Selective-black absorbers absorb solar radiation and have low infrared thermal emis-sivity; transparent heat mirrors transmit solar radiation and reflect thermal radiation. We have used rf sputtering to prepare both selective-black absorbers (Cr-black and MgO/Au on metal substrates) and transparent heat mirrors (Ti02/Ag/Ti02, Sn-doped 1n203, and Sn-doped 1n203 microgrids) with excellent wavelength-selective properties for solar energy applications such as solar heating, solar/thermal/electric conversion, and window insulation.