摘要： Enhancing state of health (SOH) estimation accuracy and robustness for battery systems in photovoltaic (PV) systems is a feasible way to improve system performance and economics. Nevertheless, the SOH is not directly measurable and affected by a number of factors, therefore its estimation is challenging. Plenty of SOH estimation methods have been proposed for different applications, but little evaluation and discussion have been made for the SOH estimation for battery management systems in PV systems. In this paper, SOH estimation methods are categorised according to the signals that are used to extract the health indicator. Most methods are based on voltage characteristics while other signals such as temperature, ultrasound and force are also promising for SOH estimation. For each method, the basic theory, advantages and drawbacks are introduced and discussed. Then, a thorough comparison among the existing methods is conducted to provide readers with a comprehensive understanding of the development of the SOH estimation. Finally, key issues and suggestions on the SOH estimation are discussed to give novel insights to researchers and engineers.