Research on Improving the Efficiency of Secondary Battery in Stand-Alone solar system
Date Issued
2009
Date
2009
Author(s)
Ho, Pei-Yi
Abstract
The research is mainly on improving the efficiency of secondary battery in stand-alone solar system. During daytime, try to find a way to increase the charge power. That is, increasing the energy stored in battery. On the other hand, considering both performance and cost, choose the best secondary battery under high ambient temperature. For increasing storage energy, this research used supercapacitor and lead acid battery in parallel. First, build the dynamic models of lead acid battery and supercapacitor and design a PI controller to limit the charge and discharge voltage. After that, using Matlab Simulink models charge energy under different climates. Besides, doing the out field tests in NTU, measures the real charge energy everyday. From the results, both simulation and out field tests showed that paralleling supercapacitor can increase 25% of storage energy on sunny days, 10% more on cloudy days and almost the same as the system without supercapacitor on rainy days. Comparing to out field test, the model has less than 5% error.About under high ambient temperature, the research compared 3 different types of secondary battery: lead acid battery AGM type, lead acid battery Gel type and Li ion battery. As the result, Li-ion battery has the most expensive price but the longest life time. However, considering about rebuild fee of changing batteries, Li-ion battery is the cheapest one among these three by using 3 years. Once decreasing the lead acid battery to 30%, it can save 70% cost.
Subjects
solar system
secondary battery
lead acid battery
super-capacitor
Type
thesis
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