TECHNOLOGY FOCUS - ELECTRONICS - Preferred Cell: In the thin-film PV cell, the BC structure has thicknesses and compositions to optimally reflect certain wavelengths of light back into the semiconductors and optimally transmit other wavelengths through the device. The interfacial buffer layers are positioned between the TCO and semiconductors and/or between the semiconductors and the BC, these layers are chosen to reduce the effects of any pinholes or weak diodes on the performance of the cell or module and to adjust the energy band alignments to facilitate electron and hole transport across interfaces. The BC comprises very thin layers of copper, thin layers of gold, alloys of copper, alloys of gold and combinations, such layers being transparent. The BC includes a transparent conductive layer such as a TCO. The thickness of the copper is 0.2-3.0 nm and the thickness of the gold is 3-30 nm. The BC includes layers selected from silver, nickel, aluminum and titanium. The semiconductors are cadmium sulfide (CdS), cadmium telluride (CdTe) and alloys of CdTe such as cadmium zinc telluride (CdZnTe). The back contact comprises one or more metallic and dielectric layers to produce a transparent conducting layer in which the metal may be silver (Ag) and the dielectric may be silicon dioxide (SiO2). The silver-based transparent layer has a thickness of 3-30 nm. The structure of the PV cell incorporates monolithic integration to connect individual cell strips of substantially equal area into a series integration such that the output voltages of the individual cells add. An inverter is incorporated to provide power output at an AC voltage, the inverter may be on the PV cell or otherwise incorporated into the window, skylight, canopy, or other structure incorporating the PV cell. Moreover, a battery pack is connected off grid to the PV cell to provide local storage of a direct current (DC) voltage generated by the PV cell, the DC voltage from the battery pack is available for use by DC powered devices. A second pane of glass and a sealing mechanism is provided to form the PV cell into an insulated window unit (IGU). A flexible polymer which incorporates suitable encapsulation to remain flexible and transparent, and still provides protection from moisture and oxygen is used as a substrate/superstrate. Preferred Method: In fabricating the thin-film PV cell that is intrinsically semitransparent, generates electricity and transmits visible light, the sputtering process is carried out at a temperature of 150-350 degrees C, preferably less than 250 degrees C. A back contact layer is applied to the polycrystalline layer by a sputtering process. The semitransparent back electrode layer can include one or more transparent conductive materials with appropriate doping elements. A transparent electrode layer of any one or more of the group zinc oxide (ZnO), zinc sulfide (ZnS), cadmium oxide (CdO), tin dioxide (SnO2) and indium oxide (In2O3) is deposited onto the transparent substrate. The transparent electrode layer and/or the semitransparent back electrode layer can include transparent multilayer ultra-thin metal coatings, such as silver (Ag), gold (Au), copper (Cu), aluminum (Al), nickel (Ni) which are electrically conducting. Furthermore, a very thin high resistivity transparent (HRT) layer of any one or more of the group ZnO, ZnS, CdO, SnO2 and In2O3 is deposited on the transparent electrode layer. The HRT layer can include materials that are without intentional doping, highly resistive and optically transparent. A high resistivity interfacial layer, preferably an HRT layer which is p-type such as zinc telluride (ZnTe) with optionally small dopant densities of nitrogen (N) or Cu is applied to the back electrode layer. The sputter process is carried out at a sputter gas pressure in the range from of 3-50 mTorr and the sputter distance is from about 15 cm to about 5 cm. The sputter gas pressure is preferably in the range from about 5 mTorr to about 15 mTorr.