THE PRINCIPAL PROJECT GOAL IS THE DEMONSTRATION OF A HIGH-PERFORMING 4-TERMINAL FAPBI3-PEROVSKITE/CI(G)S TANDEM MODULE OF AT LEAST 27% EFFICIENCY, PASSING THE OUTLINED DURABILITY SPECIFICATIONS BASED ON THE IEC 61215 MODULE QUALITY TEST (MQT) 10, 11, 13 AND ISOS-L-2, DEMONSTRATING AT LEAST 26% POWER CONVERSION EFFICIENCY (PCE) AFTER 6 MONTHS OF OUTDOOR TESTING, AND DEMONSTRATING PEROVSKITE TOP-MODULES AT PCE = 20.5% WITH AN APERTURE AREA EXCEEDING 500 CM2 THAT PASS MQT 21 AND ISOS-L-2 TESTING. THE PROJECT WILL BE CARRIED OUT AMONG THREE INTERNAL FIRST SOLAR R&D SITES AS WELL AS TWO LEADING ACADEMIC PARTNERS IN PEROVSKITE DEVELOPMENT AND CHARACTERIZATION. THE GOALS AND THE TIMELINE OF THE SETO PROJECT ALIGN WELL WITH FIRST SOLAR’S INTERNAL PLAN. WITH A COMBINED EMPHASIS ON EFFICIENCY, RELIABILITY, AND SCALING UP, THIS SETO PROGRAM POSES TREMENDOUS TECHNICAL CHALLENGES, BUT IF SUCCESSFUL, WILL PROVIDE A PATHWAY FOR A COMMERCIALLY VIABLE, BEYOND 25% PCE, THIN-FILM ONLY PV TECHNOLOGY.