1.1. Context
The global growth of distributed energy resources (DER), particularly photovoltaic (PV) systems, has been driven by the need to reduce dependence on fossil fuels and mitigate climate change impacts [
1,
2,
3]. As installation costs decrease and technological advancements improve efficiency, solar energy has emerged as a viable alternative for both residential and commercial consumers [
4,
5]. However, PV adoption is influenced by more than just economic factors; psychological, social, and regulatory elements also play a significant role [
6,
7,
8]. Moreover, recent studies have emphasized the need to consider behavioural, psychological, and contextual factors in PV adoption, particularly in regions facing socioeconomic barriers [
9,
10].
Additionally, government incentives and stable energy policies have been critical drivers of PV adoption, with countries implementing successful policy frameworks experiencing higher growth rates [
11,
12,
13]. Nonetheless, in Ecuador, regulatory hurdles, government-subsidized tariffs, and bureaucratic permitting have been identified as major obstacles to widespread PV implementation [
14]. However, the recent energy crisis has triggered a noticeable increase in PV system adoption, as frequent power outages have pushed consumers to seek more reliable and autonomous energy solutions [
15]. Consequently, this shift illustrates how external pressures, such as supply instability, can temporarily outweigh structural barriers and accelerate the transition toward distributed renewable energy. Furthermore, unlike previous studies that correlate PV adoption with high energy consumption, recent evidence suggests that even moderate energy consumers are adopting PV technology, challenging traditional user selection models [
15,
16]. This underscores the need for context-aware methodologies capable of integrating qualitative factors beyond economic metrics, especially in response to crisis-driven adoption behaviours [
17].
Moreover, while numerous studies have analysed the impact of distributed energy resource (DER) integration on power distribution systems, most have focused on highly simplified grid segments, such as a single feeder or substation [
18], gradually increasing PV penetration until reaching the grid’s operational limits. However, these localized analyses fail to account for the broader, system-wide effects of high PV penetration, particularly in the selection of potential adopters, which is crucial for projecting a more realistic generation capacity and accurately assessing its impact on distribution grids.
Therefore, this study aims to provide a comprehensive assessment of DER integration across an entire real distribution grid, enabling long-term planning strategies that ensure the continuous and high-quality supply of electricity to all users. By evaluating DER deployment at a full-grid scale, this research offers a more accurate representation of adoption trends, allowing for a deeper understanding of the technical challenges and operational measures required to maintain grid stability, power quality, and infrastructure resilience under increasing PV penetration. Additionally, this aligns with recent literature emphasizing the importance of integrated planning and operational strategies to manage the reliability and stability challenges posed by high levels of renewable energy penetration in power systems [
19].
1.2. State of Art
The adoption of PV systems is influenced by multiple economic, social, and regulatory factors. Principal drivers include cost savings, energy independence, and environmental impact [
1,
6,
20]. Additionally, energy self-consumption has emerged as a strategy to maximize solar generation benefits, although government incentives and regulatory frameworks play a crucial role in determining feasibility [
21,
22,
23]. Countries with stable energy policies exhibit higher PV adoption rates, whereas regulatory uncertainty hinders market growth [
11,
12,
15]. In Ecuador, for instance, regulatory hurdles, government-subsidized tariffs, and bureaucratic permitting have been identified as major obstacles to widespread PV implementation [
14].
Nevertheless, despite its benefits, PV adoption is not homogeneous as it varies according to socioeconomic status, access to financing, and consumer perception [
20,
24]. Older populations tend to show less interest in PV systems due to long investment payback periods, while lower-income households face economic barriers, reinforcing the need for financing programs [
7,
13,
20]. Furthermore, education levels and financial stability have been identified as key determinants of adoption behaviour [
25].
From a social perspective, peer influence and trust in technology significantly impact adoption decisions [
26,
27,
28]. Studies have shown that PV adoption is higher in communities where solar systems have already been installed, indicating a diffusion effect [
16,
24,
26]. This effect refers to the social phenomenon whereby the adoption of a new technology by some members of a community increases the likelihood of its adoption by others. In the context of PV systems, seeing Neighbors or peers adopt solar technology builds trust, reduces perceived risk, and thus encourages imitation. This social networking effect is further reinforced when economic benefits are shared among consumers within the same community [
8,
24]. In this regard, future assessments may benefit from analysing collective PV adoption models in residential apartments, particularly in settings where individual installation faces spatial or ownership constraints [
29]. Recent analyses have shown that user perception, social trust, and awareness campaigns are pivotal in shaping adoption behaviours, especially in emerging markets [
9,
10].
Furthermore, several methodological approaches have been applied to model the adoption of photovoltaic (PV) systems, including machine learning algorithms [
30], agent-based modelling [
28], multi-criteria decision analysis [
24], and fuzzy logic frameworks [
31]. In particular, recent reviews have highlighted that the suitability of these methods depends on data availability and the interpretability required for decision-making [
32]. In this context, the authors in [
30] developed a machine learning-based model using Gradient Boosting Decision Trees to predict potential PV adopters, addressing issues of data imbalance and limited samples through focal-loss supervision and synthetic data generation. Their work demonstrated high predictive capability when detailed consumer profile datasets were available.
However, such data-driven approaches are often unsuitable in contexts with limited historical information or incomplete user records, as is the case in many developing regions. Specifically, in Ecuador, where PV adoption is still emerging, utilities do not yet maintain comprehensive datasets on user characteristics, installation patterns, or system performance. This restricts the applicability of supervised learning methods that rely on large-scale, labelled data for effective training. Consequently, fuzzy logic emerges as a practical and adaptable alternative for such contexts. It remains effective in environments with data scarcity and also enables planners to integrate expert judgment through interpretable rule-based reasoning [
33,
34,
35]. Moreover, fuzzy systems provide transparency and flexibility using linguistic variables and simple membership functions such as triangular and trapezoidal shapes [
36], making them suitable for utilities that require intuitive models to support decision-making and policy planning. Its ability to handle vagueness and model dynamic, real-world phenomena through flexible rule-based structures and hybrid models combining expert knowledge with data-driven techniques further reinforces its applicability in complex environments [
37].
Nevertheless, although advantageous, the mass adoption of PV systems presents challenges for distribution grids. Studies have shown that high PV penetration can cause voltage stability issues, increased transformer loads, and potential overloading of grid assets [
22,
28,
38]. Additionally, in some scenarios, PV adoption has led to the “death spiral” phenomenon, where self-generation reduces the customer base of electric utilities, leading to tariff increases and further incentivizing PV adoption [
38,
39].
Moreover, recent simulation studies have demonstrated that the use of advanced modelling tools, such as the CYMDIST simulator, enables better evaluation of PV system impacts on the grid, identifying areas for improvement and mitigation strategies [
40]. Thus, to address voltage stability issues, reactive power compensation and advanced inverter control strategies have been proposed [
15,
41]. Furthermore, integration of PV systems in real-world distribution networks has also been analysed using detailed simulations to assess their impact on voltage profiles, losses, and asset ageing, showing the need for adaptable planning tools [
17,
42].
Despite the variety of methodologies previously explored, there is a noticeable gap in the literature regarding the use of fuzzy logic to predict photovoltaic system adoption under real distribution grid conditions. This study contributes to filling that gap by presenting a methodology that is both technically rigorous and suitable for developing countries, where data availability is often limited. The proposed approach offers a comprehensive framework that begins with user selection based on multiple contextual variables and integrates expert knowledge through the configuration of fuzzy rules such as the 2024 energy crisis in Ecuador. This adaptability makes it suitable for replicating in different technical and regulatory environments. Moreover, the use of quasi-static simulation enables the dynamic behaviour of the grid to be assessed during solar influence hours by incorporating typical daily load curves scaled to the coincident peak demand day and the generation profile of a typical PV system [
43]. This planning criterion captures the most critical grid conditions and allows for realistic assessment of voltage stability, loadability, and energy losses [
44]. The methodology thus provides an interpretable and scalable tool to support long-term planning decisions, helping utilities in emerging economies to identify infrastructure vulnerabilities, prioritize reinforcements, and develop effective policies for DER integration.
In this context, an adoption model based on fuzzy logic is proposed, integrating energy consumption with other variables such as electricity tariff, solar radiation, and socioeconomic level to identify users with a higher probability of adopting PV systems. Four different models were developed, each combining energy consumption with one or more of these variables to determine the most accurate predictive approach [
45,
46]. Furthermore, a comparative analysis was conducted against a previous study that used a fixed consumption threshold for user selection, evaluating both methodologies against real adoption data [
15]. Finally, the impact of DER on critical electrical parameters of the distribution grid was modelled, simulated, and analysed. This assessment considered voltage profile, infrastructure loadability, and energy losses, providing valuable insights into the long-term challenges and benefits of PV system penetration in distribution grids. This work provides a valuable tool not only for energy planning and public policy formulation but also for supporting the sustainable expansion of cities, contributing to population development aligned with long-term environmental and social sustainability goals. Therefore, through the application of advanced prediction, the results obtained can be used by electric utilities in Ecuador and governmental entities to design strategies that encourage the adoption of solar energy and guarantee the long-term stability of the electric grid. Thus, this paper is structured as follows:
Section 2 describes the materials and methods used;
Section 3 presents the results and the discussion of the main findings. Finally,
Section 4 summarizes the conclusions drawn from the study.