Development of a Low-Cost Integrated 20 kW-AC Solar Tracking Subarray for Grid-Connected PV Power System Applications; Final Technical Report

Utility Power Group (UPG) completed manufacturing modifications and power-processing improvements for larger utility-interactive systems using PV subarray unit building blocks of 7- to 15- kW. These can be interconnected to construct multi-megawatt PV fields. UPG determined that the most important factor to reduce costs and improve reliability was to bring as much of the field installation workas possible onto the factory floor; they implemented this approach to develop a modular panel of frameless PV laminates and an integrated power control system. UPG established a manufacturing process for integrating PV laminates into pre-assembled, field-deployable modular panels. Individual frameless PV laminates are factory-mounted and interconnected into Modular Panels (MP), then mounted intorecyclable shipping fixtures and delivered to the field, ready for placement on the ground-support structure. For power conversion, UPG enhanced the performance of power-related balance-of-system (BOS) components by integrating power conversion/control electronics, array-tracking control electronics, source circuit protection hardware, and DC and AC switchgear into a single, pre-assembled unittermed an Integrated Power Processing Unit (IPPU). The IPPU is a 3-compartment enclosure designed to be mounted in the center of each sub-array, with the tracking mechanism attached to the back. The IPPU inverter is 3-phase, 96% efficient with less than 3% total harmonic distortion over a 25% to 100% output range. UPG also refined area-related BOS costs associated with the field installation ofsingle-axis tracking PV power systems. The company accomplished their objectives, achieving a 40% reduction in area-related BOS costs and reducing net total costs of their systems by 23%. Systems were deployed for beta-testing, and 700 kW of new PV power systems were deployed during 1996 and 1997.