A 50 WATT DC-AC INVERTER FOR STAND-ALONE AND GRID-CONNECTED PHOTOVOLTAIC APPLICATIONS

FOR BOTH UTILITY-INTERTIED AND STAND-ALONE PHOTOVALTAIC (PV) SYSTEMS, THE DC WIRING AND ITS ASSOCIATED ISSUES IS ALWAYS, EXCEPT FOR THE SMALLEST OF SYSTEMS, A MAJOR PROBLEM. AC POWER TRANSMISSION TECHNIQUES WILL BE USED TO COMPLETELY ELIMINATE DC INTERCONNECTION. THIS WILL BE DONE BY INCORPORATING A SMALL DC-AC INVERTER ON THE BACK OF EACH PV MODULE SO THAT THE MODULE OUTPUT IS STANDARD 120 VOLTS, 60 HZ, AC CURRENT. AC POWER TRANSMISSION CAN BE USED FOR BOTH UTILITY-INTERACTIVE AND STAND-ALONE SYSTEMS. A MAJOR ADVANTAGE OF THESE SYSTEMS IS COMPATIBILITY 8 THE 120 V AC BUS PROVIDES A COMMON GROUND FOR ALL COMPONENTS TO INTERCONNECT. THE BENEFITS OF MAXIMUM POWER POINT TRACKING ON AN INDIVIDUAL MODULE BASIS, THE ELIMINATION OF DC WIRING, CUSTOM STRING COMBINERS, BLOCKING DIODES, SERIES STRING LOSSES AND THE STANDARDIZATION OFFERED BY A COMMON 120V AC BUS VOLTAGE CAN OUTWEIGH THE ADDITIONAL COST OF THE INVERTER. IN PHASE I OF THE EFFORT, A PROOF-OF-CONCEPT 50 WATT DC TO AC INVERTER THAT IS DESIGNED TO MOUNT ON THE BACK OF A PHOTOVOLTAIC MODULE WILL BE DEVELOPED. IT WILL DELIVER 120 VOLT 60 HZ AC POWER TO THE UTILITY GRID OR TO A LOCAL STAND-ALONE GRID. APPROPRIATE MANUFACTURING TECHNIQUES (E.G. APPLICATION-SPECIFIC INTEGRATED CIRCUITS, HYBRID CIRCUITS, MONOLITHIC AND "SMART POWER" APPROACHES) WILL BE EXAMINED, ESTIMATES OF INVERTER SIZE AND THE COST AND EFFICIENCY FOR VARIOUS SCALES OF PRODUCTION WILL BE PREPARED, AND THE FEASIBILITY OF INCORPORATING STORAGE ELEMENTS WITH THE INVERTER ON THE BACK OF THE PV MODULE TO MAKE TRULY MODULAR STAND-ALONE PV POWER SYSTEMS WILL BE STUDIED.