European Stars And Stripes (Newspaper) - May 31, 1986, Darmstadt, Hesse                                By Walter Sullivan new York times. Sour s everal intriguing developments in the design of photovoltaic cells devices that convert sunlight directly to electricity Are helping to reawaken interest in solar Energy. Man of the most significant advances in solar technology have occurred so recently that Energy specialists say there has no yet been time to evaluate their Ong Lerm reliability or to develop their Lull potential. Nevertheless these specialists say sunlight is. Expected to emerge As an important source of the nation s Energy when Oil and Gas prices inevitably Rise again. The most recent development announced in april by researchers at Stanford University is a Navel solar cell that has reached 27.5 percent conversion Elf Clancy. With modifications its efficiency is expected to reach 30 percent. Until now the Best Silicon based solar cell efficiency was 21 percent. Other advances have coma in designs that use computer guided Sun tracking mirrors or dishes to focus sunlight on Central Power towers or containers of liquid or Gas producing vapor that in turn drives engines or turbines. V these advances could also reduce the Cost of generating stat Energy to the Point thai it will rival conventional fuels by the end of the Century according to an assessment by the electric Power research Institute an organization sponsored by More than 450 Utility companies across the United slates. Although Many Utility companies Are already experimenting with Large scale solar Power plants it is the photovoltaic cells that Are exciting the most interest the cell developed at Stanford uses a parabolic Mirror to concentrate sunlight to 600 times its Normal intensity. After entering tha cell this concentrated Light is then reflected Back and Forth Between thin layers of. Silicon dislodging exec Roris to form an electric current. The Stanford device is known As a Point Contact cell because the electric current is collected at Small metallic Contact Points on the Backol the cell. The use of the tiny Points As collectors instead of the full surface used in previous designs allows most of the surface area of the Back layer to serve As a reflector. Photons reflected Oil the Back in turn Are trapped by the text sized surface of the top layer. Further increasing the cell s electrical efficiency. While the poll con act cell is considered a. Breakthrough the  Atso has Bright Hopes for other cell designs that use multiple layers of semiconductors and respond to Rifle real parts of the solar spectrum. A special Appeal of these multilayer Coll is their ability to produce electricity from diffuse sunlight making. Them applicable in regions where hazy or Cloudy Days Areco Moa scientist have discovered that extremely thin and Light semiconductor layers can be produced by spraying Silicon Gas onto supporting layers of steel or Glass. The resulting films of amorphous Silicon so called positive and no Gill  harnessing the Power of the Sun two new methods for convening Sotar Energy to electricity Are expected to achieve nearly 30 percent Ettic ency. Insofar Call illustration above photons reflected Back at id Forth bet Ween the Bottom and a textured top surface Knock Loose negatively charged electrons and positively charged  these Migrate to Bottom where they Are collected to generate a currant. At left sunlight is focused by giant Mirror onto tank containing Hydrogen which expands to drive a Piston Generator. Page 16 the stars and stripes saturday. May 31, 1986