Development of a dynamic–thermal model for an industrial lithium battery integrated into a photovoltaic system

Nakama V.; Nájera J.; Rosas D.S.Y.; Lafoz M. · Journal of Energy Storage (2026) · DOI: 10.1016/j.est.2026.121989

Resumen

This document presents the development of two mathematical models for an industrial lithium battery. For this purpose, a (Formula presented), (Formula presented) Li–FePO4 battery from the Pylontech brand was used. This battery operates within a photovoltaic system with energy storage installed at the laboratory of the “Centro de Energias Renovables y Uso Racional de la Energia de la Universidad Nacional de Ingenieria” (Center for Renewable Energy and Rational Use of Energy of the National University of Engineering), located in Lima, Peru. The mathematical models include the dynamic and thermal models of the lithium battery. The electrical behavior observed in the battery is not solely attributed to the battery as an electrochemical element but is also influenced by the power system that connects it to the photovoltaic system, the control system and the internal instrumentation. The developed models are validated using experimental data from the electrical response of the battery when the photovoltaic system operates under a specific photovoltaic production and consumption profile. Additionally, it is observed that noise in the current signal increases as its value decreases. Therefore, to achieve results with acceptable precision, two algorithms were implemented for smoothing the current signal, which serves as an input variable for the developed models. A total of 96% of the calculated NRMSE values fall below 5%, encompassing comparisons between measured and simulated voltage, current, and power of the battery under the various operating conditions evaluated, which provides clear evidence of the strong performance of the proposed models.

Instituciones: Universidad Nacional de Ingeniería