Optimization of a solar power station with LiFePO4 accumulators
¹Czech Technical University in Prague, Faculty of Electrical Engineering, Department of Electrotechnology, Technicka 2, CZ 166 27 Pague 6, Czech Republic
²Czech University of Life Sciences in Prague, Faculty of Engineering, Department of Electrical Engineering and Automation, Kamycka 129, CZ 165 21, Prague 6 ˗ Suchdol, Czech Republic; *Correspondence: papezovas@tf.czu.cz
Abstract:
The paper describes the design and construction of an isolated solar power station supplying energy at weekends to a remote location. The system comprises two parts: a photovoltaic system generating electric energy in sunlight, and an accumulator accumulating energy to be permanently available and to be able to supply a peak power of several kW. The design of the system optimized with respect to maximum reliability, ease of operation and minimum purchase costs. The control circuits were therefore constructed by means of simple analog circuits. To use microcomputers, which are nowadays used in battery management systems most often available on the market, is not appropriate. Such a system, compared with a simpler analog system, is less reliable. Power circuits are again designed in order to ensure minimum complexity of the system. The resulting design is absolutely different from conventional designs offered by suppliers of photovoltaic systems. The photovoltaic part of the system is designed for optimum adaptation of the load characteristic of the photovoltaic generator to the charging characteristic of the accumulator. By selecting photovoltaic panels with appropriate parameters and their appropriate interconnection, possibly by an automatic change of their interconnection during the charging cycle, it is possible to achieve more effective utilization of the charging power of the photovoltaic generator than by using charging DC/DC converters. The accumulator used in the system is formed by an assembly of LiFePO4 accumulators which thanks to their outstanding durability in spite of their high price currently show the lowest cost per accumulated kWh.
Key words:
LiFePO4 accumulator, photovoltaic panel characteristic, solar power