Optimal Selection of Extensively Used Non-Isolated DC–DC Converters for Solar PV Applications: A Review

Abstract

Energy consumption has drastically increased to meet the growing demand of domestic and industrial usage needs. This has led to a significant rise in the contribution of renewable energy sources, owing to their eco-friendly nature. Solar photovoltaic (PV)-based power generation plays an important role and is growing rapidly. However, it faces challenges due to its inherently low output voltage and non-linear characteristics, which limit its efficiency and performance. These limitations necessitate the use of DC–DC converters to optimize voltage levels and ensure efficient energy transfer, making them a crucial component in PV systems. Among them, non-isolated converters were preferred due to their compact size and their ability to effectively control the output of solar PV. This article critically reviews various non-isolated DC–DC converters, such as conventional, hybrid, and high-gain converters, and analyzes their performance for optimal selection. A thorough study, including mathematical modeling and performance validation through simulation, is presented in detail. The critical discussion and comparison of the various converters will significantly help design engineers and researchers in selecting the appropriate converter for solar PV applications.

1. Introduction

Due to the increasing energy demand in domestic and industrial applications, global attention for energy generation is shifting away from fossil fuels toward renewable energy sources [1,2] since fossil fuels are finite and have a severe environmental effect in terms of greenhouse gases (GHGs) or global warming. The solution to the problem is to use renewable energy sources due to their sustainable and eco-friendly nature. Among different renewable sources, solar energy has significant contributions. The shift to solar PV-based power generation is owing to its environmentally friendly nature, ease of accessibility, low maintenance, and the progress of PV technology in recent years [3]. In the current scenario, the power electronic circuits are primarily designed with RESs instead of voltage divider circuits to regulate the output due to their lower efficiency [4].

Power electronic converters are classified into four categories: DC–DC, DC–AC, AC–DC, and AC–AC converters. DC–DC converters are generally implemented with renewable energy sources (RESs) for regulating and controlling the DC output voltage [5], as shown in Figure 1. DC–DC converters are classified into two types: isolated and non-isolated converters [6]. Galvanic isolation separates the input and output sides of an isolated converter, leading to a common ground point and output terminals that can be positive or negative, with no input effect on the output [7]. However, the transformer provides a high conversion ratio, with limitations such as high cost, weight, size, core saturation, linked inductor leakage inductance, and magnetic interference. Non-isolated DC–DC converters are economical, compact in size, and have fewer components [8,9,10,11,12] than isolated converters; however, they have lower voltage gain. Non-isolated converters, such as buck, boost, and buck–boost, are conventional converters.

In contrast, hybrid converters such as Cuk, SEPIC, and Zeta are designed with the addition of two conventional DC–DC converters [13]. The Cuk converter is the combined form of the boost and buck converters in front and loads side structure, respectively. In contrast, the SEPIC converter is designed with the addition of boost and buck–boost converters in the front end and across the load terminal, respectively. A zeta converter is formed by hybridizing the conventional buck–boost and buck converters in the front end and the load terminal. Therefore, researchers considered these hybrid converters to be a type of conventional converter. However, conventional and hybrid converters have lower voltage gains, high switching losses, and poor efficiency at high power [14]. Therefore, to work efficiently and reliably in high voltage applications for stepping up the input voltage, the researchers focus on the high gain DC–DC converters for obtaining the high step-up voltage from the lower input voltage source.

In high-power applications, high-gain DC–DC converter topologies have been developed, integrating features such as an interleaved structure, quasi-Z-source networks, a switched capacitor, and switched inductors [15]. Beyond topological advancements, emerging power semiconductor technologies, such as wide-bandgap materials (GaN and SiC), have revolutionized power conversion by enabling higher efficiency, lower conduction losses, and higher switching frequencies [16]. These materials allow for compact high-power-density designs suitable for modern PV applications. Furthermore, soft-switching techniques (zero-voltage switching (ZVS) and zero-current switching (ZCS)) have been implemented to minimize switching losses and improve overall efficiency [17]. High-frequency operation also contributes to reducing passive component sizes, making converters more compact and efficient. High-gain converters have high voltage gain and lower switching losses but have limitations such as complex control, being expensive, being larger, and requiring more components [18,19]. As a result, it can be stated that every converter has its pros and cons, and selecting a particular converter for a design engineer is a major task when fulfilling the requirements of specific applications. Therefore, in this paper, various topologies of non-isolated converters are reviewed based on their performance parameters, and out of them, selected converters are analyzed through the simulation results to make an optimal selection of the converter that would be easiest for researchers and solar PV system design engineers to work with.

2. System Configuration

This work focuses on the performance evaluation of the non-isolated DC–DC converter converters. Non-isolated DC–DC converters are preferred for standalone PV systems due to their higher efficiency, compact design, and lower cost. They efficiently regulate voltage for battery charging and DC loads without the need for isolation, making them ideal for off-grid applications. In contrast, grid-connected PV systems often require isolated converters to ensure safety, high voltage gain, and protection against grid faults, making non-isolated converters less suitable for feeding power into the high-voltage grid. Therefore, a standalone solar PV system feeding DC load is considered. The system configuration is depicted in Figure 2a. It comprises a solar PV array, non-isolated DC–DC converters, MPPT controllers, and the DC link. The non-isolated converters are interfaced between the PV array and the DC link to regulate solar PV output. The MPPT controllers are used to provide the appropriate switching signal to the converters to obtain maximum power. The mathematical modeling of each converter is designed based on the switch-mode operation.

2.1. Solar PV Array

Figure 2b shows a single-diode model of a PV cell. The panel cells are arranged in series and parallel combinations to obtain the required rating. The I/V and P/V characteristics of the solar PV array designed for the system are shown in Figure 2c,d, respectively.

From the circuit analysis of the single-diode PV model shown in Figure 2b,

$$I=I_{ph}-I_D-I_{sh}$$

(1)

The current across the shunt resistance (I_sh),

$$I_{sh}=\left(V+I{R}_{se}/R_{sh}\right)$$

(2)

The current across the Diode (I_D),

$${ \mathrm{I}}_{\mathrm{D}}{=\mathrm{I}}_{\mathrm{o}}\left\{\exp \left({\displaystyle \frac{\mathrm{V}+\mathrm{I}{\mathrm{R}}_{\mathrm{se}}}{{\mathrm{V}}_{\mathrm{T}}}}\right)\right\}$$

The output current of a solar cell can be expressed as,

$$\mathrm{I}={\mathrm{I}}_{\mathrm{ph}}-{\mathrm{I}}_{\mathrm{o}}\left\{\exp \left({\displaystyle \frac{\mathrm{V}+\mathrm{I}{\mathrm{R}}_{\mathrm{se}}}{{\mathrm{V}}_{\mathrm{T}}}}\right)\right\}-{\displaystyle \frac{\mathrm{V}+\mathrm{I}{\mathrm{R}}_{\mathrm{se}}}{{\mathrm{R}}_{\mathrm{sh}}}}$$

(3)

where, I_ph—photo-generated current, I_D—diode current, I_o—reverse saturation current, V_T—Thermal Voltage, R_se—Series branch resistance, R_sh—Shunt branch resistance.

2.2. Maximum Power Point Tracker (MPPT)

Maximum power point tracking algorithms are essential for optimizing solar PV power extraction. Effective control strategies play a crucial role in ensuring stability, dynamic performance, and efficiency in non-isolated DC–DC converters. Conventional MPPT techniques such as Perturb and Observe and Incremental Conductance are widely used due to their simplicity and real-time adaptability [20]. Advanced methods like Fuzzy Logic Control [21] and Artificial Neural Networks [22] enable intelligent, adaptive control by learning from system behavior and optimizing power tracking under rapid irradiance changes. Particle Swarm Optimization [23], a nature-inspired algorithm, also enhances MPPT efficiency by dynamically adjusting control parameters.

Moreover, sophisticated techniques, such as Sliding Mode Control [24], provide robust, nonlinear control, ensuring fast convergence and high resilience against variations and partial shading. Digital control methods using microcontrollers and DSPs enable real-time adaptive control, improving system efficiency and response under dynamic conditions [25]. Integrating these advanced control strategies with MPPT techniques allows modern high-gain DC–DC converters to achieve higher reliability, efficiency, and adaptability for standalone and grid-connected PV applications. Therefore, to analyze the performance of non-isolated DC–DC converters, i.e., the analysis of the system, conventional MPPT techniques were used as they are simple and easy to implement.

2.3. Non-Isolated DC–DC Converters

Non-isolated DC–DC converters can be broadly classified as conventional, hybrid, and high-gain converters, as depicted in Figure 3. Conventional DC–DC converters have a simple structure and easy control, while they have lower voltage gain. Hybrid DC–DC converters are designed by merging two conventional converter circuits in a single unit [26]. Due to the lower gain of these conventional hybrid converters, they also suffer from the limitations of lower gain output. On the other hand, high-gain converters are designed to have boosted output. Thus, they have a wide range of applications, especially suitable for renewable energy as solar PV systems for acquiring high voltage gain and high efficiency [27].

2.3.1. Conventional Non-Isolated DC–DC Converter

Conventional DC–DC converters can be broadly classified as buck, boost, and buck–boost converters. The buck converter works as a step-down converter; therefore, the voltage received across the load is always less than the source voltage, as shown in Figure 4a. On the other hand, the boost converter is a step-up converter; therefore, the acquired output voltage is always greater than the source voltage. In the boost operation, the diode becomes reverse-biased during the turn-on condition of the switch, and the energy is stored in the inductor. The diode becomes forward-biased when the switch is turned off, and the boosted output is obtained, as shown in Figure 4b. A buck–boost converter is a combined form of the buck and boost converters; therefore, depending on the application, it can be used as a step-up or step-down converter. In the buck–boost operation, the buck converter works as a step-down converter, whereas the boost converter performs as a step-up or boosting converter, as depicted in Figure 4c. These DC–DC converters are designed based on the converter’s switching mode operation, and the required size of passive elements is determined by the mathematical modeling of the converter, as shown in

Table 1. Comprehensive review of different non-isolated conventional and hybrid DC–DC converter topologies.

Ref.	Converter	Voltage Gain (VG.)	NS	NL	NC	ND	Power (W)	VO (V)	Control	Application
[28]	Boost	${\displaystyle \frac{1}{(1-D)}}$	1	1	1	1	878	28.00	PI + FLC	Standalone PV
[29]	Buck-Boost	${\displaystyle \frac{-D}{(1-D)}}$	1	2	1	1	2190	350.00	INC + VSI	Single-phase IM fed with solar PV
[30]	Buck/Boost	D	1	1	1	1	50	17.20	P&O + ANFIS	PV System
[31]	Buck-Boost	${\displaystyle \frac{-D}{(1-D)}}$	1	2	1	1	100	24.00	IC + PLL	PV grid integration
[32]	SEPIC	${\displaystyle \frac{D}{(1-D)}}$	1	2	2	1	2024	489.30	PID	PV
[33]	LUO	${\displaystyle \frac{D}{(1-D)}}$	1	2	2	1	6000	210.00	INC + VSI	BLDC Motor fed with PV
[34]	SEPIC	${\displaystyle \frac{D}{(1-D)}}$	1	2	2	1	200	230.00	P&O + FLC	PV

N_S—number of switches, N_L—Number of inductors, N_C—Number of capacitors, N_D—Number of diodes.

.

2.3.2. Hybrid Non-Isolated DC–DC Converters

Hybrid DC–DC converters such as Cuk, SEPIC, and Zeta are designed by hybridizing the two conventional converters, and they can also be termed derived converters or modified converters. The conventional buck and boost converters were merged into the Cuk converter, which can be used as a step-up or step-down converter. In the Cuk converter, the load side structure is a buck converter, while the front structure is a conventional boost converter, as shown in Figure 4a’. The SEPIC converter functions as both a step-up and step-down converter; it is derived from the conventional buck and boost converters at the front end and across the load terminal, respectively, as depicted in Figure 4b’. The Zeta converter is designed from the buck and buck–boost converters at the front end and across the load terminal, respectively, as depicted in Figure 4c”. Hybrid converters also have the limitation of lower voltage gain; therefore, most researchers and design engineers consider hybrid converters as a type of traditional DC–DC converter.

In [28], a boost converter is interfaced between the PV module and the resistive load to control the PMDC motor smoothly and effectively. The PI and FLC feedback controllers govern the functioning of the converter. According to the results, it was observed that the boost converter has a better response using FLC than the PI controller. The buck–boost converter is used in [29] for the induction motor drive application fed with solar PV. A bidirectional DC–DC converter is also used to control the battery’s power transfer. In [30], both the boost and the buck converters are used with the P&O and ANN-based MPPT controllers for analyzing the performance of each of the converters. A prototype model is also developed to examine the viability and performance assessments. According to the results, the buck converter outperformed the boost converter under dynamic test conditions. In [31], the buck–boost converter was implemented with solar PV, and the power was fed to the grid via the H bridge inverter. A prototype model was developed to examine viability and evaluate performance. In [32], various configurations of the converters, such as boost, Cuk, and SEPIC, are used with a closed-loop PID controller. According to the performance assessment, the SEPIC converter performed efficiently and outraced the other converters. In [33], both the positive and negative output Luo converters are interfaced with solar PV for BLDC motor drive applications. According to the simulation’s results, it was observed that the positive output Luo converter performed efficiently as compared to the negative output Luo converters. In [34], the SEPIC converter is implemented for the application of solar PV with both the MPPT controller P&O and FLC. The results showed that the SEPIC converter had less ripple and fluctuation using FLC than P&O. The comparison of different non-isolated conventional and hybrid DC–DC converter topologies are shown in Table 1.

2.3.3. High-Gain DC–DC Converter

In [35], a novel high-gain boost converter topology with fewer components—one switch, two inductors, two capacitors, and three diodes—was proposed, as shown in Figure 4a”. A prototype model was developed to examine this high-gain converter’s viability and performance evaluation for application in solar PV and hybrid vehicles. In [36], a novel high-gain buck–boost converter topology was proposed, as shown in Figure 4b”, which consists of three inductors, three capacitors, five diodes, and a single switch. The output voltage of this high-gain converter can be stepped up/down in accordance with the requirements of the application. In [37], a novel topology of the high-gain SEPIC converter was proposed, as shown in Figure 4c”, which is derived from the conventional SEPIC converter and has a single switch, three inductors, three capacitors, and three diodes. A prototype model was developed to examine this high-gain converter’s viability and performance evaluation in renewable energy applications.

In [38], a novel extended zeta converter circuit based on a high-voltage gain was presented for PV applications. This topology was developed by combining a high-voltage gain converter and a conventional Zeta converter to overcome the limitations of voltage gain in conventional Zeta converters. An experimental prototype was set up to validate the simulation results. According to [39], a conventional double boost and conventional SEPIC converter were merged into an integrated double boost converter, increasing the proposed converter’s voltage gain. This converter is suitable for PV and FC applications since it has a low input current ripple. This high-gain converter also had a lesser weight, size, and simple structure, and performed efficiently. The proposed converter in [40] combines the features of the quadratic boost and Cuk converters to increase voltage gain as well as provide simple control. Drops in the inductor and resistor and across the power switch caused a minor difference between the simulation and the experimental results. According to [41], a novel high-gain boost converter is implemented with a hybrid PV system that includes solar PV, a battery bank, and a bidirectional DC–DC converter. Using battery bank as a hybrid source, the high gain converter regulates the output across the DC link, and a bidirectional converter is used to maintain the system’s performance under dynamic test conditions. The bidirectional converter charges and discharges the battery in the buck and boost modes. A novel high-gain converter is presented in [42], based on a quadratic boost and voltage multiplier cell combination. Since it has an input inductor, it performs better in FC applications due to fewer ripples in the input current. The converter discussed in [43] is the combined form of the buck and buck–boost converters with an additional inductor added to the buck–boost converter to overcome the limitations of the standard buck–boost converter, and simulation results were validated by an experimental setup. In [44], both the unidirectional and bidirectional converters are used to maintain the adequate performance of the hybrid system. The proposed topology is based on cascaded converters, which provide high voltage gain. The comparison of different non-isolated high-gain DC–DC converter topologies is shown in

Table 2. Comprehensive Review Summary of Non-Isolated High-Gain DC–DC Converters.

Ref.	Voltage Gain (VG.)	NS	NL	NC	ND	VO (V)	Power (W)	Efficiency (%$\mathit{\eta }$)	Frequency (kHz)	App.
[38]	${\displaystyle \frac{4D}{(1-D)}}$	6	2	6	5	220	100	91.00	10	PV
[39]	${\displaystyle \frac{2+D}{(1-D)}}$	1	2	5	4	240	100	97.83	50	PV & FC
[40]	${\displaystyle \frac{1+D}{{(1-D)}^2}}$	1	3	4	4	200	250	94.00	20	FC
[41]	${\displaystyle \frac{1}{D(1-D)}}$	1	2	2	2	700	27.93	98.79	40	PV
[42]	${\displaystyle \frac{1}{{(1-D)}^2}}$	1	2	2	3	96	40	88.00	60	FC
[43]	${\displaystyle \frac{D^2}{{(1-D)}^2}}$	4	3	2	4	24	200	93.60	20	PV
[44]	${\displaystyle \frac{(2-D)(1+D)}{D^2}}$	2	3	5	4	46.4	50	90.25	50	EV

N_S—number of switches, N_L—Number of inductors, N_C—Number of capacitors, N_D—Number of diodes.

.

A non-isolated interleaved boost converter is developed in [45], which provides an efficient, compact, and high-performance solution for high-voltage applications. The converter employs coupled inductors, active clamping, and a voltage multiplier circuit to minimize switching losses, reduce voltage stress, and achieve soft switching. A non-isolated Z-source DC–DC converter is designed for high step-up photovoltaic (PV) applications [46]. The converter achieves a higher voltage gain while maintaining low voltage stress on semiconductor devices. Unlike traditional boost converters, which require extreme duty cycles to achieve high voltage gain, this design enhances efficiency by using a voltage multiplier and a coupled inductor network. The circuit ensures soft switching, eliminating reverse recovery issues in output diodes, thereby reducing power losses. Additionally, the clamped switch voltage improves device reliability, while the low duty cycle operation minimizes switching stress. In [47], a non-isolated quasi-Z-source (QZS)-based high-gain DC–DC converter with switched capacitors is developed to overcome the limitations of traditional Z-source converters, such as low voltage gain, high voltage stress, and discontinuous input current. The QZS converter achieves high voltage gain for a duty cycle of less than 0.5 while maintaining continuous input current and reduced voltage stress on switching components. A high-gain, high-efficiency SEPIC-based DC–DC converter for renewable energy applications is proposed in [48], integrating a quasi-resonant topology with a coupled inductor and voltage multiplier circuit. The circuit achieves high voltage gain without extreme duty cycles, reducing voltage stress across switching components. The soft-switching (zero-current switching, ZCS) operation minimizes switching losses, while the lossless passive clamp circuit recycles leakage energy, enhancing efficiency. The converter also ensures continuous input current with low ripple, making it ideal for photovoltaic (PV) and other renewable systems. In [49], a non-inverting buck–boost converter enhances efficiency by ensuring soft-switching for all transistors, significantly reducing switching losses. The circuit employs a triple coupled inductor, two resonant inductors, and auxiliary diodes, which enable continuous current flow through the main inductor, thereby minimizing current ripple and improving power quality. A multi-input boost DC–DC converter is designed in [50] for renewable energy systems, ensuring continuous input and output currents, which improve system reliability and efficiency. Unlike conventional converters, it integrates multiple input sources such as PV panels, batteries, and fuel cells, enabling flexible power management. The boost topology with continuous current flow minimizes ripple, reduces filter size, and extends component lifespan.

3. Performance Analysis for Optimal Selection of the Converter

The critical analysis of selected non-isolated DC–DC converters, such as conventional, hybrid, and high-gain DC–DC converters, is presented in this section. In order to evaluate the performance of the converters, each topology is examined based on an output response, conversion parameters such as duty ratio, efficiency, and the required application. To examine the performance of non-isolated DC–DC converters, the selected topologies were implemented with the solar PV system and analyzed based on Simulink results. The mathematical modeling of each configuration is designed based on the switch-mode operation. Both the P&O and INC MPPT controllers are used to validate the performance of the circuit topology.

Table 3. Specification of the PV panel used.

Panel Parameters	Values
The maximum Power rating of a panel, Pm	255 W
Open circuit voltage of panel, Voc	38.46 V
Rating of Short circuit current, Isc	8.89 A
Current at Maximum Power, Im	8.16 A
The voltage at Maximum Power, Vm	31.24 V
Current temperature coefficient, KT	0.07
Voltage temperature coefficient, Kv	−0.35601
Number of panels in series Ns	08
Number of panels in parallel Np	05

shows the parameters of the PV module used.

3.1. Conventional and Hybrid DC–DC Converter

The conventional and hybrid DC–DC converters are positioned between the PV array and the load terminal to step up the voltage from 250 V to 800 V. The P&O MPPT controller provides the switching pulse to the converters to acquire the desired response from the SPV system. The passive elements of the converters are designed based on switch mode operation as defined in

Table 4. Designing Parameters of Conventional & Hybrid DC-DC Converters.

Converter Type	L1 (mH)	L2 (mH)	C1 (µf)	C2 (µf)	RL (Ω)
Boost Converter	27.50	-	107	-	64
Buck–Boost	30.47	-	119	-	64
Cuk Converter	9.52	22.86	119	1.30	64
SEPIC Converter	9.52	22.86	119	1.30	64
Zeta Converter	9.52	22.86	3.26	1.30	64

and

Table 5. Mathematical modeling of Non-Isolated DC-DC converters.

S. No	Passive Elements	Mathematical Model of Passive Elements
		Boost	Buck-Boost	Cuk	SEPI	Zeta
1	Inductor L1 (mH)	${\displaystyle \frac{D{V}_{in}}{f_s\Delta I_L}}$	${\displaystyle \frac{D{V}_{in}}{f_s\Delta I_{L1}}}$	${\displaystyle \frac{D{V}_{in}}{f_s\Delta I_{L1}}}$	${\displaystyle \frac{D{V}_{in}}{f_s\Delta I_{L1}}}$	${\displaystyle \frac{D{V}_{in}}{f_s\Delta I_{L1}}}$
2	Inductor L2 (mH)	-	-	${\displaystyle \frac{D{V}_{in}}{f_s\Delta I_{L2}}}$	${\displaystyle \frac{D{V}_{in}}{f_s\Delta I_{L2}}}$	${\displaystyle \frac{D{V}_{in}}{f_s\Delta I_{L2}}}$
3	Capacitor C1 (µF)	${\displaystyle \frac{D{I}_s}{f_s\Delta V_{C1}}}$	${\displaystyle \frac{D{I}_o}{f_s\Delta V_{C1}}}$	${\displaystyle \frac{(1-D)I_{in}}{f_s\Delta V_{C1}}}$	${\displaystyle \frac{D{I}_o}{f_s\Delta V_{C1}}}$	${\displaystyle \frac{D{V}_{in}}{8{f_s}^2{L}_1\Delta V_{C1}}}$
4	Capacitor C2 (µF)	-	-	${\displaystyle \frac{D{V}_{in}}{8{f_s}^2{L}_2{C}_1}}$	${\displaystyle \frac{D{I}_o}{f_s\Delta V_{C2}}}$	${\displaystyle \frac{D{V}_{in}}{8{f_s}^2{L}_2\Delta V_{C2}}}$

, and the mathematical analysis of the circuits is validated through the simulation results shown in Figure 5. In this section, each converter’s critical analysis and performance are evaluated in terms of passive elements, output voltage and current, output power, output parameter stability, and the efficiency of the SPV system, as shown in

Table 6. Obtained results of conventional and hybrid DC–DC converters.

DC–DC Converter	Input Voltage (V)	Input Current (A)	Output Voltage (V)	Output Current (A)	Output Power (W)	Efficiency (%)
Boost	250.6	40.67	792	12.37	9797	96.04
Buck-Boost	247.5	41	791	12.38	9792	96.00
Cuk	247.67	41.10	792	12.36	9789	95.97
Sepic	250.5	40.70	783	12.25	9591	94.03
Zeta	247.3	41.18	792.5	12.40	9827	96.34

.

As per the obtained results, the Zeta converter performed efficiently despite the limitations of higher fluctuations across the DC link, as shown in Figure 5. The Cuk converter had fewer fluctuations in output voltage and current than boost, buck–boost, and Zeta converters but required a higher number and size of passive components. Among all conventional and hybrid DC–DC converters, the Boost converter had the fewest passive elements and performed efficiently except for the Zeta converter for this solar PV-based application.

3.2. High-Gain DC–DC Converters

Various configurations of a recently proposed high-gain DC–DC converter integrated with a solar PV system are examined in this article. These high-gain converters are implemented with a 10 KW SPV system, where high-gain DC–DC converters boost the solar PV array from 250V, as obtained across the DC link, to 800 V output voltage. The P&O and INC-based MPPT controllers provided the switching pulse to the high-gain converters to acquire the maximum power. Each converter’s performance is analyzed in terms of output voltage and current, output power, efficiency, DC link fluctuations, and the required size of passive components. The converters’ mathematical modeling and performance analysis are carried out and verified through MATLAB/Simulink 2018a, as shown in

Table 7. Mathematical modeling of non-isolated high-gain DC–DC converter.

Passive Elements	Boost	Buck– Boost	SEPIC
Inductor, L1 (mH)	${\displaystyle \frac{D{V}_{in}}{f_s\Delta I_{L1}}}$	${\displaystyle \frac{D{V}_{in}}{f_s\Delta I_{L1}}}$	${\displaystyle \frac{D{V}_{in}}{f_s\Delta I_{L1}}}$
Inductor, L2 (mH)	${\displaystyle \frac{ D{V}_{in} }{f_s(1-D)\Delta {I_L}_2}}$	${\displaystyle \frac{V_{in}D}{f_s\Delta {I_L}_2}}$	${\displaystyle \frac{V_{in}D}{f_s(1-D)\Delta {I_L}_2}}$
Inductor, L3 (mH)	-	${\displaystyle \frac{D(1+D)V_{in}}{f_s\Delta {I_L}_3}}$	${\displaystyle \frac{D{V}_{in}}{f_s(1-D)\Delta {I_L}_3}}$
Capacitor, C1 (µF)	${\displaystyle \frac{D{I}_o}{f_s\Delta V_{in}}}$	${\displaystyle \frac{D{V}_o}{{Rf}_s\Delta V_{C1}}}$	${\displaystyle \frac{D{V}_{in}}{{Rf}_s(1-D)\Delta V_{C1}}}$
Capacitor, C3 (µF)		${\displaystyle \frac{D{V}_o}{{Rf}_s\Delta V_o}}$	${\displaystyle \frac{D{V}_o}{{Rf}_s\Delta V_o}}$

and

Table 8. Obtained results of high-gain DC–DC converters.

Converter Type		Input Voltage (Volts)	Input Current (Amps)	Output Voltage (Volts)	Output Current (Amps)	Output Power (Watts)	Efficiency (%)
High Gain Boost	With P&O	252	40.15	787	12.25	9640	94.52
High Gain Buck-Boost		247	41.10	781	12.20	9528	93.42
High Gain SEPIC		244	41.50	780	12.21	9523	93.37
High Gain Boost	With I&C	253	41.5	787	12.40	9759	95.68
High Gain Buck-Boost		247	40.20	780	12.18	9500	93.14
High Gain SEPIC		245	42.50	782	12.16	9510	93.23

. According to the simulation results, the boost converters provided higher efficiency but had more output voltage, current, and power fluctuations across the DC link, as shown in Figure 6 and Figure 7. It is evident from the figures that the boost converter with I&C delivers the highest output power of 9759 W with an efficiency of 95.68%, followed by the boost with P&O. The buck–boost and SEPIC converters have slightly lower output power and efficiency. The comparison of high-gain converters in terms of current stress, output ripple, and efficiency is illustrated in Figure 8. As shown in Figure 8 the high-gain buck–boost converter experiences higher current stress on semiconductor devices than the boost and SEPIC converters. Additionally, Figure 8 illustrates that the buck–boost and SEPIC exhibits lower output voltage current ripple than the boost converter. However, the boost converter achieves higher efficiency, as depicted in Figure 8.

4. Conclusions

This paper critically analyzes and evaluates the performance of selected non-isolated DC–DC converters, specifically conventional, hybrid, and high-gain topologies for solar photovoltaic (PV) applications. The selected topologies were modelled in MATLAB/Simulink and analyzed based on different performance parameters, including output voltage, current, efficiency, and fluctuations across the DC link. The results show that the Zeta converter, with an efficiency of 96.35%, outperformed other conventional and hybrid converter topologies. Although the boost converter has less efficiency than the Zeta converter, it requires fewer and smaller passive components, making it a preferred choice for cost-sensitive applications. In high-gain converters, the boost converter has an efficiency of 94.52%, the highest among all converters, making it well-suited for grid-connected PV systems, while the SEPIC converter demonstrates the lowest voltage and current ripple of 1%, ideal for sensitive DC loads and hybrid PV-battery systems. Additionally, the study shows that Incremental Conductance (INC) outperforms Perturb and Observe (P&O), making it the preferred choice for faster and more accurate MPPT tracking in non-isolated DC–DC converter systems. This comprehensive study provides valuable insights for design engineers and researchers, assisting in the selection of the most suitable DC–DC converter for solar PV applications.