Development of prototype battery management system for photovoltaic systems

An energy and battery management system (BMS) has a great importance in PV-battery system to increase the system efficiency and battery life. In this thesis, a prototype BMS that can provide energy and battery management for an on-grid PV-battery system with 18650 type lithium-ion batteries was designed, realized and tested. Within the scope of the study, the designed prototype system consists of programmable electronic DC load that can act as a 1/15 reduction of realistic home energy consumption, 400 Wp PV module, battery block with a capacity of 353 Wh (7 series 4 parallel), 300 W power supply for obtaining energy from the grid, 24 V light bulbs (dummy load) for the sale of excess energy to the grid. For this prototype system, the control unit that consists of; • "The main circuit" that controls the energy flow between the PV system, the grid (buying, selling), battery block, household load, • four "slave circuits" include the balancing circuit capable of measuring voltages temperatures and balancing in each of the four modules with 7 lithium-ion batteries connected in series, the battery circuit, which fixes the batteries well and measures the charge / discharge currents on the battery module and also provide battery and energy management has been designed and realized. For retired and working household power consumption profiles, scenarios were created for 24-hour power consumption on different days on weekdays/weekends. These scenarios were uploaded on the electronic load, the operation of the designed battery and energy management system was tested with these experiments. The battery management system ensured that the batteries operate in safe working conditions. Due to the energy management system, when the PV-batteries system is not sufficient, the energy is taken from the grid; when the PVs charged batteries fully, the excess energy is sold to the grid.