Comparison of li-ion battery ageing models applied in photovoltaic stand-alone systems   R. Dufo-López, S. Marquino Leonar, J.L. Bernal-Agustín, J.S. Artal-Sevil, José A. Domínguez-Navarro   2017/04/25

Abstract

In this paper, three models to predict the ageing of li-ion batteries (LiFePO4/graphite) are compared. The models are applied in stand-alone (off-grid) photovoltaic (PV) - battery systems and PV - diesel (or gasoline) - battery systems. A high dependency on temperature is shown for all the models: the battery degrades at a higher rate as temperature increases. Also, all the models present a dependency on the charge and discharge rate: higher degradation occurs as charge and discharge rate increases. Also degradation is highly affected by pauses in between charge and discharge steps. Most of these dependencies are coupled and highly non-linear. In PV-battery systems the charge and discharge rate is usually low (lower than C/2), as the battery capacity is usually high (designed for several days of autonomy, usually 2-6 days). Even in PV-diesel or gasoline-battery systems this rate is low, although the battery capacity is much lower than in PV-battery systems. The models are evaluated in systems located near Zaragoza. In all the cases a 2.4 kWp PV generator is considered. The size of the battery bank and of the diesel or gasoline generator varies in the different cases. All the models show high battery life (>30 years) in cases of PVbattery systems (with a battery bank of 4 days autonomy). However, in the cases of PV-gasoline-battery systems, there is a great difference in the estimation of the lifetime obtained by the different models.

Authors and affiliations

R. Dufo-López, S. Marquino Leonar, J.L. Bernal-Agustín, J.S. Artal-Sevil, José A. Domínguez-Navarro
Department of Electrical Engineering. EINA, University of Zaragoza. (Spain)

Key word

Li-ion battery, ageing models, photovoltaic, off-grid.

References

[1] Comparative study of stand-alone and hybrid solar energy systems suitable for off-grid rural electrification: A review,
Renew. Sustain. Energy Rev. 27 (2013) 738–752. doi:10.1016/j.rser.2013.06.043.
[2] R. Dufo-López, J.M. Lujano-Rojas, J.L. Bernal-Agustín, Comparison of different lead–acid battery lifetime prediction
models for use in simulation of stand-alone photovoltaic systems, Appl. Energy. 115 (2014) 242–253.
doi:10.1016/j.apenergy.2013.11.021.
[3] Wang, J. Liu, P, Hicks-Garner, J. Sherman, E. Soukiazian, S. Verbrugge, M. Tataria, H. Musser, J. Finamore, P. (2011) Cycle- life model for graphite-LifePO4 cells. Journal of Power Sources (196), 3942- 3948
[4] Groot J. (2014) State-of -Health Estimation of Li-ion Batteries: Ageing Models. PhD Thesis. Chalmers University of
Technology, Sweden.
[5] Groot, J. Swierczynski, M. Stan, A.I. , Kaer, S.K. (2015) On the complex ageing characteristics of high-power LiFePO4/ graphite battery cells cycled with high charge and discharge currents. Journal of Power Sources. (286) 475-487