Development of a Grid-Connected Photovoltaic-Storage

This paper presents the design and studies performed in the first-phase implementation of the R&D project D308, in partnership with Energetic Company of Minas Gerais (CEMIG-D). The objective of this project is to evaluate the benefits and limitations of using storage with a grid-connected PV system. Specifically to evaluate injecting the energy stored in batteries charge by the PV into the electric grid in order to flatten the peak of the load curve of a feeder system (with evening peak-electricity consumption experienced in this area). The PV/storage system is being installed in the football stadium Arena do Jacare, located in Sete Lagoas, Minas Gerais. Initial studies have been performed to define the characteristics of the PV array, including surveys of the region characteristics, and solar resource/climate data. Additionally, the characteristics of the optimum PV generator configuration and module technology have been evaluated, taking into consideration the stadium's limited available area and defined orientation--and the major design criterion to eliminate any shadow projection on photovoltaic modules that could reduce its performance. With the initial design of the PV generator structure and geometry, the system was performance was simuulated under projected conditions. An innovative feature of this project is a bidirectional conversion and connection unit, which has the capacity to store the energy coming from the PV generator and/or the electrical network in a battery bank. The unit can deliver the energy to the grid (a feeder operated by CEMIG in our tests) at specific defined times-such as the peak time in this area between 18:30 and 20:30. At the conclusion of this protype project, a larger scale of the system (photovoltaic system connected to the network with storage) will be installed at GREEN-IPUC/PUCMinas, utilizing the lessons learned and experiences and the equipment developed at the Minas Gerais Arena do Jacare Stadium.