Solar, Volume 3, Issue 2 (June 2023) – 8 articles

Photovoltaic (PV) technology plays a crucial role in the transition towards a low-carbon energy system, but the potential-induced degradation (PID) phenomenon can significantly impact the performance and lifespan of PV modules. PID occurs when a high voltage potential difference exists between the module and ground, leading to ion migration and the formation of conductive paths. This results in reduced power output and poses a challenge for PV systems. Research and development efforts have focused on the use of new materials, designs, and mitigation strategies to prevent or mitigate PID. Materials such as conductive polymers, anti-reflective coatings, and specialized coatings have been developed, along with mitigation strategies such as bypass diodes and DC-DC converters. Understanding the various factors that contribute to PID, such as temperature and humidity, is critical for the development of effective approaches to prevent and mitigate this issue. This review aims to provide an overview of the latest research and developments in the field of PID in PV modules, highlighting the materials, designs, and strategies that have been developed to address this issue. We emphasize the importance of PID research and development in the context of the global effort to combat climate change. By improving the performance and reliability of PV systems, we can increase their contribution to the transition towards a low-carbon energy system. Full article

This paper presents a new fractional-order proportional-integral, (PI)${}^{\lambda }$ (FO[PI]) type structure to investigate the load frequency control (LFC) problem. In the literature, some controllers’ extensive tuning options may slow or complicate the optimization process. Due to the intricacy of the tuning, even if there are fewer tuning parameters, a robust structure can be obtained. The (PI)${}^{\lambda }$ structure deviates from the standard FOPI, integer PID, or PI-PD controllers with the same or fewer tuning parameters. The efficacy of a tri-parametric fractional-order controller is examined on a two-area interconnected hybrid power system comprising a photovoltaic (PV) grid and a Reheated Thermal Generator (RTG). In order to obtain optimal performance with lower control efforts, a novel dual-performance index is developed for the LFC problem. Various analyses are also proven to perform better than other optimized controllers from the recent literature. The presented scheme is significantly robust to disturbance interruptions, non-linearities, and parameter perturbations. It is also observed that there are no stability issues due to communication time delays. It is highlighted that the improvement can be obtained without adding complex structure or controller parameters. Full article

This work aimed to show the possibility of applying anthocyanins extracted from blueberries following a straightforward path as potential impregnation dyes in dye-sensitized solar cells (DSSCs), particularly in the presence of co-adsorbents, such as silver nanoparticles, as an alternative in order to profit from large amounts of discarded fruits. Following a simple procedure, anthocyanins (mainly delphinidin-3-glucoside) were obtained from blueberries (Southern Highbush type). Complete characterization was carried out in order to prove the utility of delphinidin-3-glucoside as a sensitizer in DSSCs. The analyzed anthocyanin is suitable for sensitizing because of its high molar absorptivity values within the visible region of the light spectra, the adsorption ability to a FTO/TiO₂ electrode (FTO, fluorine-doped tin oxide) as confirmed by Fourier transform infrared (FTIR) as well as thermogravimetry coupled to differential scanning calorimetry (TG-DSC), a potential oxidation value near 1 V, and adequate thermal as well as light stabilities. Moreover, the cell’s conversion efficiency is improved in the presence of silver nanoparticles, reaching 0.24% (nearly a 25% increase). The sum of all these characteristics points to the application of delphinidin-3-glucoside as a sensitizer in DSSCs, offering a technological use with potential interest for countries where agricultural production offers an abundant origin of extraction. Full article

The paper presents the analysis of energy retrofitting, integration of renewable energy and activation of energy flexibility in a cluster of buildings in the surroundings of a port on the Mediterranean Sea in Southern Italy, with the aim of checking the potential for it to achieve the status of positive energy district (PED). The objective of this study is to improve the contemporaneity between local energy generation and energy demand and reduce CO_2eq emissions by considering signals that reflect the environmental variability of the electricity grid, through flexibility solutions applied to the HVAC system. The proposed scenarios are based on the dynamic simulation of the district and analyze the effect of actions that activate the energy flexibility of buildings through advanced control strategies of the air conditioning system. The results show that the joint action of energy efficiency strategies, integration of solar energy and energy flexibility improves the environmental sustainability of the district and the balance of energy flows. Specifically, the activation of energy flexibility contributes to a 10% reduction in operational CO_2eq emissions and increases in self-consumption of energy per year. The operational emissions of the district vary from the base value of 33.37 tons CO_2eq/y to 19.52 tons CO_2eq/y in the scenario based on the integration of solar energy systems and energy efficiency measures, and to 17.39 tons CO_2eq/y when also the demand-side energy flexibility is activated. Full article

The use of traditional Dye-sensitized solar cells (DSSCs) is limited due to the use of toxic and non-environmentally safe solvents. In this review, water is proposed as a viable alternative to developing green chemistry and sustainable materials for DSSCs. However, water-based DSSCs (WBDSSCs) require improvement in their photovoltaic parameters. The detachment of dye molecules from the semiconductor and the poor solubility of iodine in water are the primary reasons for their low efficiency. This review analyzes the best results achieved by 100% aqueous electrolytes containing synthetic, organic, and natural dyes to identify the best conditions to overcome these limitations. Developing a suitable photoanode/electrolyte interface and finding a compromise in the choice of dye are the main research goals in the coming years. WBDSSCs can contribute significantly to producing clean energy using sustainable and environmentally friendly materials. Furthermore, here we report the state of the art of the emerging technology of underwater dye-sensitized solar cells, which are a promising technology for generating renewable energy in aquatic environments. Recent advancements in material science and device engineering have shown promising results in enhancing their efficiency and durability. Further research and development can make these devices a viable alternative for sustainable energy generation in a wide range of underwater applications. Full article

This paper provides an overview of the development of a 3D formed and metal-based facade element that combines a custom design and solar thermal functionality. To achieve this, a novel simplified solar thermal collector structure was developed using formed sheet metal half-shells with an integrated channel structure on the inside and a special absorber coating on the outside. The sheet metal half-shells were manufactured by highly innovative incremental sheet forming (ISF), which allows seamless integration into existing facades. As a part of this paper, the initial test results on thermal efficiency and the energy accumulation of the new collector type are presented. Full article

Concentrating Photovoltaic Thermal (CPVT) collectors are suitable for integration in limited roof space due to their higher solar conversion efficiency. Solar sunlight can be used more effectively by CPVT collectors in comparison to individual solar thermal collectors or PV modules. In this study, the experimental investigation of a novel CPVT collector called a PC (power collector) has been carried out in real outdoor conditions, and the test set-up has been designed based on ISO 9806:2013. A quasi-dynamic testing method has been used because of the advantages that this method can offer for collectors with a unique construction, such as the proposed collector, over the steady-state testing method. With a quasi-dynamic testing method, it is possible to characterize the collector within a wide range of incidence angles and a complex incidence angle modifier profile. The proposed novel collector has a gross area of 2.57 m². A maximum power output per collector unit area of 1140 W is found at 0 °C reduced temperature (1000 W/m² irradiance level), while at a higher reduced temperature (70 °C), it drops down to 510 W for the same irradiance level. The data have been fitted through a multiple linear regression method, and the obtained efficiency curve coefficients are 0.39, 0.192, 1.294, 0.023, 0.2, 0, −5929 and 0 for K_θd, b₀, c₁, c₂, c₃, c₄, c₅ and c₆, respectively. The experimental characterization carried out on the collector proved that the output powers calculated by using the obtained parameters of the quasi-dynamic testing method are in good agreement with experimental points. Full article

Reverse breakdown in Cu(In,Ga)S${\mathrm{e}}_2$ (CIGS) solar cells can lead to defect creation and performance degradation. We present pulsed reverse-bias experiments, where we stress CIGS solar cells with a short reverse voltage pulse of ten milliseconds and detect the electrical and thermal response of the cell. This way, we limit the duration of the reverse stress, allowing us to study the initial stages of reverse-bias defect creation in CIGS solar cells and modules. Our results show that permanent damage can develop very fast in under milliseconds. Furthermore, we find the location of defect creation as well as the susceptibility to defect creation under reverse bias depends strongly on whether the cell is encapsulated or not, where encapsulated cells are generally more robust against reverse bias. Full article