## 1 Introduction  
PV energy represents an excellent energy source for remote and standalone systems due to its availability and scalability. It also represents a clean source of energy that continues to grow and contribute to the move to a more balanced energy mix and a sustainable clean future for energy on Earth. From that fact stems the need for efficient energy delivery systems such as inverters, battery chargers, and other power supplies that interface the PV source to the consumer [1]. In standalone PV systems, PV battery chargers typically use PWM DC/DC converters such as boost or buck-boost converters to charge local batteries [2, 3]. These basic types of converters are simple and well established in terms of both control simplicity and design, but they have drawbacks such as hard-switching characteristics. In switch-mode DC/DC converters, hard switching refers to the fact that every time the semiconductor switch turns on and off, it loses a considerable amount of power due to having to cut the current or force it to zero immediately [4]. The switching loss in hard-switched converters limits the switching frequency and therefore the compactness of the system, because the higher the switching frequency, the smaller the passive and energy-storing elements needed [5]. Several researchers have proposed different soft-switching DC/DC converters for PV applications [6, 7, 8, 9, 10]. Even though these convertersimprove the overall efficiency of the system, their control complexity and high number of switches and passive elements make them impractical topologies for PV battery chargers. Resonant converters present a viable solution for efficiency and compactness due to their ability to utilize resonance to perform switching under soft conditions, a zero voltage, or a zero current [11]. Several resonant converters have been proposed in the literature for PV applications [12; 13; 14; 15]. However, these converters rely on isolation transformers, which increase the size and losses of the system. A capacitive isolated resonant converter has not been discussed in the literature for PV applications. A capacitive isolated resonant converter eliminates the need for a transformer; this could significantly reduce magnetic core losses and overall system size, which are important advantages for low-voltage standalone PV applications. Instead, if capacitive galvanic isolation is used, it will provide effective electrical separation between the input and output without bulky magnetic components. Having a PV system requires having the ability to extract the maximum power available in it, which is a task usually performed by a DC/DC converter. There are multiple methods or control algorithms that can be used to perform maximum power point tracking (MPPT), such as perturb and observe (P&O) algorithms, incremental conductance algorithms, and other algorithms that require some sort of knowledge of the system's dynamics [16; 17]. This means that, if a resonant converter is chosen, the control complexity becomes much higher than that of a basic DC/DC converter. This is an essential reason for why boost and buck-boost converters are chosen over more efficient converters. It is the familiarity with the dynamic and linearized models of these converters that makes them desirable for use with conventional MPPT methods. Model-independent MPPT methods present an opportunity to utilize converters that are difficult to linearize and control, such as resonant converters. One of these methods is extremum-seeking control (ESC) [18; 19]. The ESC method has been utilized in MPPT applications, such as in Refs. [20; 21; 22]. It offers great advantages, as it does not require previous knowledge of the system's model or dynamics. However, in the literature, there are no cases that utilize it with more complex converters. Most of the studies conducted with extremum-seeking control in MPPT applications utilize basic converters, which do not utilize the full potential of the algorithm.