A performance study of the photovoltaic integrated with hybrid battery system for peak power reduction

Abstract

One of the greatest practices in energy management is the Energy Storage System (ESS). ESS can be used for renewable energy control as well as peak shaving in the build-up of a Smart Grid. The cost of a lithium ion battery is more than 200 percent greater than that of a lead-acid battery, which is a significant barrier to project start-up. This paper discusses the use of a hybrid energy storage system that includes a lithium-ion battery and a lead-acid battery. This work presents the hybrid energy storage using lithium-ion battery and lead-acid battery, which aims at reducing costs of the project. However, usability that requires high current power supply considerably affects the usable capacity of a lead-acid battery. According to the test, it was found that the ratio 68.63: 31.37 was the most suitable among 7 ratios, compared to the model building installed a 50kW solar power generator on the rooftop, in the worst case scenario when the batter have 85% DoD per cycle .The EOL for hybrid energy storage is about 4 years lifespan with the 0.5C and 0.2C for LFP and AGM respectively. In terms of economic evaluation, hybrid energy storage could initially reduce the project cost by 47.5%.

Most large and controlled buildings require high power demand with long period. However, there are restrictions on building facilities and image when it comes to reducing electricity consumption. Another option is to install a roof-top solar power system, though due to the small installation area, it will only partially reduce energy use. Hybrid energy storage systems in combination with AGM batteries and LFP batteries are now offered as a lower cost energy management solution. AGM batteries are constrained in their ability to produce current, hence a larger current supply will reduce the battery's useable capacity. Therefore, in order to respond to high demand with long period, this research proposed a separate multi-level threshold control of the battery packs, and used the control factor in the form of current ratio to divide the load response for each battery type: On-Peak in AGM: LFP at 0.7 : 0.3, Off-Peak in AGM : LFP at 0.5 : 0.5. And when one battery was not ready for use, the other battery would be run at full capacity. The results showed that the AGM battery had a peak discharge current of 12.7A, or approximately 0.5C when coupled with an LFP battery, and when processing power storage system capacity, a loss of 8.99 kWh occurred, the hybrid energy storage system had an efficiency of 93.20%, And when taking the electricity produced from the solar power generation system compared to the incident solar radiation, it would be found that the efficiency of the solar power generation system would be 76.74%. Therefore, when considering the total efficiency of the solar power generation system combined with the hybrid energy storage system, the efficiency was 71.52%.

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