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The output energy produced by the photovoltaic system strongly depends upon the amount of solar radiation harvested by the photovoltaic panels. Varying the tilt of photovoltaic panels at the optimal angle and/or cleaning the photovoltaic panels at regular intervals are some of the techniques that could enhance the photovoltaic system performance albeit at the cost of increased labor and water budget. Here, we explore a farm-level study to investigate the effect of different tilt angle adjustment schedules on the performance of conventional north/south ( N / S ) tilted monofacial photovoltaic farms. We further compare the performance of optimally tilted N / S photovoltaic farms with that of east/west (E / W) faced vertical bifacial photovoltaic farms for various dry periods for Lahore, Pakistan. We show that for a dry period of one month, the performance of N / S tilted farm is decreased by ∼ 40 kWh/m2 as compared to that for E / W farm that exhibits a performance degradation of ∼ 3 kWh/m2. Further, N / S farm performs better than E / W vertical farm if the cleaning is performed on (or before) fortnightly basis. Further, if cleaning is delayed for one month, then E / W vertical farm performs better than N / S tilted farm. The results presented in this work are beneficial for the development of E / W faced vertical bifacial farm in dusty climates and regions with scarce water supply. [ABSTRACT FROM AUTHOR]

Bifacial solar technology has experienced exponential growth in recent years and its trend is increasing for the coming years. Considering the advantages that it offers over monofacial technology such as its current price equivalence, the increase in performance thanks to the production of the rear face and the consecutive reduction of the LCOE, it is logical that more and more photovoltaic plants with this technology are been installed. Nowadays, there are some regulatory gaps regarding bifacial technology and, due to this growing trend, it is necessary to study, research and implement the optimal way to evaluate these systems. This article has experimented with a 3.3 kW bifacial photovoltaic system, divided into two strings with different configurations, whose monitoring system has all the instrumentation included in the IEC 61,724 standard, with the addition that it has several rear irradiance sensors arranged in different locations of the system to evaluate the variability of this parameter. After an experimental campaign of 9 months, a power estimation analysis and the calculation of the PR and PR25°C have been carried out using the different rear irradiance sensors. The variability of this parameter depending on the location of the sensor has affected the results in such a way that the RMSE committed in the power estimation has varied between 10.22% and 2.63%, while the PR and PR25°C of the system has oscillated between 0.84 for the most unfavorable case and 0.95 in the most favorable case. Assumed the great variability between performance ratios, it is necessary to establish a specific normative standard for the evaluation of Bifacial PV systems. [ABSTRACT FROM AUTHOR]

Perovskite solar cells have become promising candidates for thin‐film photovoltaics (PV), but many record cells suffer from losses in current (≈3–4 mA cm−2). This is due to the choice of superstrate configurations (i.e., glass‐side illumination) and thin absorber layers, typically on the order of ≈500 nm. Illumination through a top transparent conductive oxide electrode (substrate configuration) using LiF and Al2Ox as anti‐reflective coatings leads to reflectance losses below 1% is demonstrated. When combined with 1 µm thick absorber layers, substrate configurated bifacial devices have power conversion efficiencies >20%, with minimized reflection losses approaching 98% of their detailed‐balance limits and higher Jsc than their monofacial counterparts. Further analysis is conducted to show there is still a significant fraction of current lost due to poor charge‐carrier extraction (e.g., resistive or low mobility contacts). This is studied by a direct comparison of photoluminescence at short‐circuit versus open‐circuit estimating a 4.5% loss in charge‐carrier collection. [ABSTRACT FROM AUTHOR]

We present a radiative cooling material capable of enhancing albedo while reducing ground surface temperatures beneath fielded bifacial solar panels. Electrospinning a layer of polyacrylonitrile nanofibers, or nanoPAN, onto a polymer-coated silver mirror yields a total solar reflectance of 99 %, an albedo of 0.96, and a thermal emittance of 0.80. The combination of high albedo and high emittance is enabled by wavelength-selective scattering induced by the hierarchical morphology of nanoPAN, which includes both thin fibers and bead-like structures. During outdoor testing, the material outperforms the radiative cooling power of a state-of-the-art control by ∼20 W/m2 and boosts the photocurrent produced by a commercial silicon cell by up to 6.4 mA/cm2 compared to sand. These experiments validate essential characteristics of a high-albedo radiative-cooling reflector with promising potential applications in thermal and light management of fielded bifacial panels. [ABSTRACT FROM AUTHOR]

The evolving landscape of Floating Photovoltaic (FPV) systems is marked by ongoing advancements, particularly in the refinement of floating structures and the arrangement of photovoltaic modules. Furthermore, the increasing adoption of bifacial PV modules, attributed to their capacity for heightened production densities, underscores a notable trend within the field. Concurrently, the development of specialized software tools capable of simulating bifacial floating PV systems (BFPV) is progressively unfolding. This paper seeks to contribute to the field by conducting a comprehensive assessment of the experimental and numerical energy performance of a bifacial East-West Floating PV system (EW-BFPV) leveraging bifacial modules. The evaluation entails meticulous environmental and system measurements executed over a ten-month duration at the “Enel Innovation Lab” in Catania, Italy. Moreover, the study endeavors to validate numerical results generated by two specialized photovoltaic software tools, namely PVsyst and SAM, in which models of the EW-BFPV system have been implemented. Central to this validation is the examination of the Energy Performance Index (EPI) and the Baseline Energy Performance Index (BEPI). This assessment integrates both observed performances based on measured meteorological data and predicted performance to ensure a comprehensive evaluation. Significantly, the research includes specific analyses aimed at assessing the influence of varying irradiance inputs on the calculation of PV module temperatures within the simulation tools. Despite inherent disparities in modeling approaches between the software tools, our findings suggest that harmonizing loss percentages can yield comparable outcomes. This observation underscores the robustness of the proposed methodology and its potential for facilitating accurate assessments of FPV system performance, thus contributing to the advancement of this burgeoning technology.

We present a radiative cooling material capable of enhancing albedo while reducing ground surface temperatures beneath fielded bifacial solar panels. Electrospinning a layer of polyacrylonitrile nanofibers, or nanoPAN, onto a polymer-coated silver mirror yields a total solar reflectance of 99 %, an albedo of 0.96, and a thermal emittance of 0.80. The combination of high albedo and high emittance is enabled by wavelength-selective scattering induced by the hierarchical morphology of nanoPAN, which includes both thin fibers and bead-like structures. During outdoor testing, the material outperforms the radiative cooling power of a state-of-the-art control by ∼20 W/m2 and boosts the photocurrent produced by a commercial silicon cell by up to 6.4 mA/cm2 compared to sand. These experiments validate essential characteristics of a high-albedo radiative-cooling reflector with promising potential applications in thermal and light management of fielded bifacial panels.

Compared with monofacial solar cells, the development of bifacial solar cells has garnered considerable attention for achieving higher power output by simultaneously harvesting direct and diffused light while incurring fewer additional manufacturing costs. Perovskite light absorbers, given their outstanding optoelectronic properties, present great opportunities for fabricating bifacial solar cells. However, one of the challenges in designing bifacial perovskite solar cells (PSCs) is that they suffer from optical and electrical losses due to insufficient light absorption in the perovskite layer. In this respect, in this work, a hot‐pressing transfer process is developed to fabricate a diffraction‐grating (DG) perovskite layer to form a bifacial PSC. The constructed DG structure on the perovskite layer improved its light‐harvesting efficiency, reduced its charge recombination, and enhanced its charge extraction properties. The bifacial DG PSC achieved power conversion efficiencies of 14.01% and 10.04% for the bottom and top illuminations, respectively, resulting in a bifaciality factor of 0.71. Therefore, the newly developed hot‐pressing transfer process for fabricating DG structures on perovskite layers is a promising technique for fabricating high‐efficiency bifacial PSCs with high bifaciality factors. [ABSTRACT FROM AUTHOR]

Bifacial solar cells are gaining popularity due to their compactness, space‐saving property, and higher photoconversion efficiency (PCE) than mono‐facial solar cells. Bifacial dye‐sensitized solar cells (BF‐DSSCs) are fabricated and characterized utilizing D‐205 as a dye sensitizer in combination with I−/I3− and Co2+/Co3+ redox electrolytes. BF‐DSSCs using iodine‐based electrolytes demonstrate a cumulative PCE and bifaciality factor (BFF) of 13.05% and 85%, respectively. The hampered PCE under backside light illumination is attributed to the absorption of photons by the electrolyte itself. Contrary to this, BF‐DSSCs fabricated using cobalt‐complex‐based redox electrolyte exhibits an exceptionally high BFF of nearly 100% with a PCE of 4.77% and 4.75% under the front‐ and rear‐light illumination, respectively. Although the open‐circuit voltage of the BF‐DSSCs fabricated using cobalt electrolyte (with deeper redox potential) is slightly higher than that of BF‐DSSCs fabricated using iodine electrolyte, their cumulative PCE (9.52%) is much lower than that of iodine‐based device counterparts (13.05%). This decrease in PCE is attributed to the relatively fast charge recombination in the cobalt‐electrolyte‐based BF‐DSSCs. [ABSTRACT FROM AUTHOR]

In view of the increasing interest and market share of bifacial cells and modules, suitable substrates such as glass and transparent backsheets along with ethylene vinyl acetate (EVA) and polyolefin elastomer (POE) encapsulants were examined in combined‐accelerated stress testing (C‐AST) to evaluate and compare degradation modes. Testing with both monofacial and bifacial cells, we found that glass–glass modules with monofacial cells led to greater grid finger breakage than those with polymeric backsheets. This is attributed to previous X‐ray topography and modeling work showing higher stress in cells and interconnections in glass–glass modules than glass backsheet modules. Consistent with the objectives of C‐AST, which stresses modules at levels corresponding to the limits seen in the natural environment, we observed the UV‐fluorescence signatures of modules tested in C‐AST (considering the degradation associated with developing chromophores, moisture penetration, and photobleaching effects) to be like those in fielded modules, more so than other chamber stress testing implemented for comparison. We found light‐induced degradation (LID) in module types with regenerated (inactive) cells with C‐AST, suggesting the possibility of LID destabilization in some field conditions. We could also distinguish potential‐induced degradation (PID) on the back of the bifacial passivated emitter and rear cells (PERC) in C‐AST. Confirming with ex situ tests, we found polarization‐type PID most prevalent in glass‐glass modules with EVA as would be anticipated considering the greater leakage current through such module encapsulation. Unlike PID tests performed in the dark, which can lead to false positive PID test results, field‐representative illumination is experienced by the modules on the front and back sides while −1200 V system voltage is applied in C‐AST, supporting the conclusion that this module type with glass‐glass construction would be susceptible to PID in the field. [ABSTRACT FROM AUTHOR]

Bifacial photovoltaics (BPVs) are a promising alternative to conventional monofacial photovoltaics given their ability to exploit solar irradiance from both the front and rear sides of the panel, allowing for a higher amount of energy production per unit area. The BPV industry is still emerging, and there is much work to be done until it is a fully mature technology. There are a limited number of reviews of the BPV technology, and the reviews focus on different aspects of BPV. This review comprises an extensive in-depth look at BPV applications throughout all the current major applications, identifying studies conducted for each of the applications, and their outcomes, focusing on optimization for BPV systems under different applications, comparing levelized cost of electricity, integrating the use of BPV with existing systems such as green roofs, information on irradiance and electrical modeling, as well as providing future scope for research to improve the technology and help the industry. [ABSTRACT FROM AUTHOR]

This study investigates the performance of agrivoltaic systems employing bifacial photovoltaic modules. A comparison between yield in Sweden and Italy was carried out. Three agrivoltaic system designs were evaluated: vertical fixed, single-axis tracker, and dual-axis tracker. The results showed that the specific production varied between 1090 to 1440 kWh/kWp/yr in Sweden and 1584 to 2112 kWh/kWp/yr in Italy, where the lowest production was obtained with the vertical fixed agrivoltaic system while the highest production was obtained with the dual-axis tracking agrivoltaic system. The vertical fixed design had a higher electricity production during low solar elevation angles, while the single-axis and dual-axis tracking designs had significantly higher power production during mid-day. The electricity production gain using a dual-axis tracker design was mostly during mid-day, but the increase compared to the single-axis tracker was only 1-2%. The study concludes that low-height, fixed agrivoltaic systems without tracking are well-suited for high-latitude countries like Sweden, while elevated systems with tracker solutions are more suitable for locations like Italy. The findings suggest that the performance of agrivoltaic systems with bifacial photovoltaic modules is highly dependent on geographical location and the specific characteristics of the crops grown beneath them.

Abstract Compared with monofacial solar cells, the development of bifacial solar cells has garnered considerable attention for achieving higher power output by simultaneously harvesting direct and diffused light while incurring fewer additional manufacturing costs. Perovskite light absorbers, given their outstanding optoelectronic properties, present great opportunities for fabricating bifacial solar cells. However, one of the challenges in designing bifacial perovskite solar cells (PSCs) is that they suffer from optical and electrical losses due to insufficient light absorption in the perovskite layer. In this respect, in this work, a hot‐pressing transfer process is developed to fabricate a diffraction‐grating (DG) perovskite layer to form a bifacial PSC. The constructed DG structure on the perovskite layer improved its light‐harvesting efficiency, reduced its charge recombination, and enhanced its charge extraction properties. The bifacial DG PSC achieved power conversion efficiencies of 14.01% and 10.04% for the bottom and top illuminations, respectively, resulting in a bifaciality factor of 0.71. Therefore, the newly developed hot‐pressing transfer process for fabricating DG structures on perovskite layers is a promising technique for fabricating high‐efficiency bifacial PSCs with high bifaciality factors.

[Display omitted] Perovskite solar cells (PSCs) have achieved remarkable progress in the past decade and become the most powerful challenger of traditional silicon photovoltaics. Among the many designs, bifacial PSCs have received widespread attention these days due to their ability to fully utilize environmental reflection and scattering light to enhance energy yield. They also can provide better aesthetic design for building-integrated photovoltaics (BIPVs). However, the potential of bifacial PSCs is not limited to these traditional applications. Importantly, such architecture also serves as a universal component for multi-junction cells and photon engineering, which are both critical for further efficiency improvement. In this review, the requirements of different functional layers under various applications are described in detail, starting from the structure of bifacial PSCs. The application developments are introduced, including albedo utilization, semitransparent PSCs (ST-PSCs), TSCs. The present issues (such as stability, large area, recombination of carriers at the back electrode and toxicity etc.) and the extra challenges of bifacial PSCs are highlighted. It is hoped that this review can provide new ideas for the future development and further improve the competitiveness of PSCs. [ABSTRACT FROM AUTHOR]

Throughout this article, we explore several generations of photovoltaic cells (PV cells) including the most recent research advancements, including an introduction to the bifacial photovoltaic cell along with some of the aspects affecting its efficiency. This article focuses on the advancements and successes in terms of the efficiencies attained in many generations of photovoltaic cell and discusses the challenges of each generation. Monocrystalline silicon dominates the solar cell market, and other technologies are still being developed in order to commercialize them. As an illustration, recent solar cell technology, known as the fourth generation and containing graphene, has been discussed. To determine if the damaged solar panel pieces would function or not, a test was conducted, it showed that even after being cut into small pieces, the open circuit voltage had not changed. The bifacial photovoltaic technology has been briefly reviewed in the review, including the substrates used, cell texturing, antireflection coating, cell reflectors, etc. Bifacial photovoltaic (PV) performance will continue to profit from studies on higher conversion efficiencies linked to monofacial PV cells. It is important to do studies within the area of bifacial PV modules in order to boost their performance, efficiency, and market value globally. [ABSTRACT FROM AUTHOR]

Key message: We examined leaves of a suite of microphyllous woody plants and describe a little-known form of leaf peltation for the first time and also investigate strongly reflexed leaves in two distantly related lineages. Plants cope with a range of environmental conditions, especially related to water relations, and have developed an array of physiological and structural solutions to maintain a functional water balance. There has been considerable recent work on physiological solutions to water deficit but little attention paid to leaf characteristics. In many species there is a change in leaf form from seedlings to adults. We examine such changes in several small-leaved species from the distantly related Asteraceae and Myrtaceae, some of which develop micropeltate or reflexed leaves as adults. All are native to dry or seasonally dry sites. Three major morphological groups were recognised as follows: (1) leaves erect, nonpeltate and scale-like (Ozothamnus hookeri), (2) leaves erect and peltate (Phaenocoma prolifera, Regelia inops), (3) Leaves reflexed (Olearia lepidophylla, Ozothamnus scutellifolius, Ozothamnus reflexifolius, Melaleuca diosmifolia). The microphyllous peltation in P. prolifera and R. inops in the absence of a meristematic fusion/bridge differs from typically peltate leaves. These small-leaved taxa occur in open, high light environments which are very different from the mesic, shaded understorey habitats of typical peltate-leaved plants. Many small-leaved species have leaves closely appressed to the stem and often with recurved margins. The erect leaves are functionally similar to reflexed leaves. Environmental filtering leads to superficially similar plant forms that may have somewhat different ontological origins. Such morphological forms are examples of convergent evolution in distantly related species but within each family are likely phylogenetically related. [ABSTRACT FROM AUTHOR]

[Display omitted] • Optimal PV system row spacing presented considering land-use and latitudes 15–75°N. • Latitude-based formulae given for optimum tracked, fixed-tilt, and vertical spacing. • Optimum tilt of fixed-tilt arrays can vary from 7° above to 60° below latitude-tilt. • Similar row spacing should be used for tracked and fixed-tilt PV arrays >55°N. • Bifacial arrays need up to 0.03 lower GCR than monofacial, depending on bifaciality. General guidelines for determining the layout of photovoltaic (PV) arrays were historically developed for monofacial fixed-tilt systems at low-to-moderate latitudes. As the PV market progresses toward bifacial technologies, tracked systems, higher latitudes, and land-constrained areas, updated flexible and representational guidelines are required. Using our 3D view-factor PV system model, DUET, we provide formulae for ground coverage ratios (GCRs –i.e., the ratio between PV collector length and row pitch) providing 5%, 10%, and 15% shading loss as a function of mounting type and module type (bifacial vs monofacial) between 17-75°N. Fixed-tilt arrays span a wide range of GCR (0.15–0.68, 5% loss) compared to single-axis tracked arrays (0.17–0.32) and vertical east–west arrays (0.11–0.16). We additionally optimize fixed-tilt module tilt, finding that the optimum tilt can vary from 7° above latitude-tilt to 60° below latitude-tilt in certain cases. We demonstrate that tracked and fixed-tilt PV arrays should have similar GCRs >55°N, but tracked systems are more sensitive to row-to-row shading losses <55°N. The GCR of fixed-tilt arrays at lower latitudes can reach 0.55 without introducing >2.5% shading loss, whereas tracked and vertical arrays reach 2.5% shading loss by GCRs <0.22 and <0.10, respectively. We additionally find that bifacial PV arrays require GCRs up to 0.03 lower than monofacial GCRs. These results can inform future deployment designs for latitudes >15°N. [ABSTRACT FROM AUTHOR]

We present our own Interdigitated Back Contact (IBC) technology, which was developed at ISC Konstanz and implemented in mass production with and at SPIC Solar in Xining, China, with production efficiencies of over 24%. To our knowledge, this is the highest efficiency achieved in the mass production of crystalline silicon solar cells without the use of charge-carrier-selective contacts. With an adapted screen-printing sequence, it is possible to achieve open-circuit voltages of over 700 mV. Advanced module technology has been developed for the IBC interconnection, which is ultimately simpler than for conventional double-sided contacted solar cells. In the next step, we will realize low-cost charge-carrier-selective contacts for both polarities in a simple sequence using processes developed and patented at ISC Konstanz. With the industrialisation of this process, it will be possible to achieve efficiencies well above 25% at low cost. We will show that with the replacement of silver screen-printed contacts by copper or aluminium metallisation, future IBC technology will be the end product for the PV market, as it is the best performing c-Si technology, leading to the lowest cost of electricity, even in utility-scale applications.

We present our own Interdigitated Back Contact (IBC) technology, which was developed at ISC Konstanz and implemented in mass production with and at SPIC Solar in Xining, China, with production efficiencies of over 24%. To our knowledge, this is the highest efficiency achieved in the mass production of crystalline silicon solar cells without the use of charge-carrier-selective contacts. With an adapted screen-printing sequence, it is possible to achieve open-circuit voltages of over 700 mV. Advanced module technology has been developed for the IBC interconnection, which is ultimately simpler than for conventional double-sided contacted solar cells. In the next step, we will realize low-cost charge-carrier-selective contacts for both polarities in a simple sequence using processes developed and patented at ISC Konstanz. With the industrialisation of this process, it will be possible to achieve efficiencies well above 25% at low cost. We will show that with the replacement of silver screen-printed contacts by copper or aluminium metallisation, future IBC technology will be the end product for the PV market, as it is the best performing c-Si technology, leading to the lowest cost of electricity, even in utility-scale applications. [ABSTRACT FROM AUTHOR]

Photovoltaics (PV) is a cost-competitive and scalable technology for electricity generation that plays a crucial role to accelerate the European energy transition and achieve carbon neutrality. Large-scale installation of rooftop PV, as well as innovative PV applications such as floating PV coupled with hydropower and bifacial PV along roads and railways, offer multi-benefits, not least in reducing competition for land. In this study, we present a geospatial approach to assess the pan-European technical potential of these three applications, using publicly available datasets. The findings reveal that the PV total installed capacity could exceed 1 TWp, which is far larger than the total PV capacity for 2030 in the EU Solar Energy Strategy (720 GWp) and would be a significant contribution to the several TWs needed for the overall transition to net-zero by 2050. The evidence presented is a useful starting point for policy-setting at national and regional level, as well as for research and detailed analyses of location specific solutions.

The considerable growth of the renewables’ shares in the energy market paves the way towards United Nations Sustainable Development Goal 7. Solar photovoltaics (PV) are more economically viable amongst other renewables because of their lower, easier installation and reliability. However, the PV, like other renewables, is more vulnerable to climatic conditions. Currently, the monofacial leads the PV market; however, it is expected that the bifacial PV will be dominant as it offers more energy yield at a lower cost. It is thus crucial to analyze the PV performance concerning climatic conditions. The merits of this study include: (i) the performance of bifacial PV for the climate change scenarios is analyzed, which is lacking in the literature; (ii) detailed monofacial and bifacial PV mathematical models are developed to estimate the PV output; and (iii) the comparison is made between monofacial and bifacial PVs performance and their dependence on climatic conditions. The climate model is used to predict the ambient conditions for the years 2050 and 2080. The average hourly responses of solar irradiance and energy yield are presented and analyzed.

Numerous aspects of performance assessment of bifacial PV have been undertaken over the years, however, an area where knowledge lacks, is concerning the negative impact of soiling on individual side of a bifacial module. An in-depth study has been presented where the soiling losses and rates for individual sides of a bifacial module have been quantified through experiments. A soiling rate of 0.328 %/day was observed for bifacial module, while the rear side soiling rate was measured to be equal to 0.031 %/day, which was significantly lower than the front of the module. The impact of wind speed and relative humidity was investigated on the soiling losses for the module, along with a detailed assessment of effect of wind direction on the soiling on individual sides of the module. A common metric to analyse bifacial modules against monofacial is bifacial gain which was observed to be greater for soiled module (13.98 %) compared to clean module (12.92 %) due to significant variation in available irradiance to the front side of the module. Finally, a comparative assessment of the impact of orientation on the soiling losses was conducted and the results showed that significantly lower soiling losses (∼2 %) and soiling rate (bifacial∼0.063 %/day and bifacial rear∼0.047 %/day) was observed for a vertically installed bifacial module. The results are significant as they direct towards the applicability of bifacial modules in regions with prevailing dust and will assist in deciding which type of mitigation strategies can be explored for individual sides of a bifacial module. • A soiling rate of 0.328 %/day was observed for bifacial module. • The rear side soiling rate was measured to be equal to 0.031 %/day. • Bifacial gain which for soiled module (13.98 %) compared to clean module (12.92 %). • Vertical installation of bifacial module resulted in lower soiling losses (∼2 %). • Wind direction plays a crucial role in determining soiling rate of individual side. [ABSTRACT FROM AUTHOR]

An overview of the Passivated Emitter and Rear Totally Diffused (PERT) solar cell is presented, which is a member of Passivated Emitter and Rear Contact (PERC) family. Due to its outstanding properties, n-type PERT is considered as a promising candidate in photovoltaics (PV). In recent years, research efforts have been devoted towards industrialization of PERT mostly based on n-type substrates to benefit from its inherent advantages. In particular, the IMEC's n-PERT developed with Jolywood, a 23.2% certified efficiency of the front side has been achieved which is almost the highest efficiency for industrial n-PERT. Currently research is focused on bifacial n-type PERT cells that are already manufactured industrially and are now in mass-produced in industry. This review is focused on the experimental approach towards monofacial PERT cells with a historical overview, PERT's structure, passivation scheme, contacts formation, light trapping and antireflection coating scheme and their corresponding process steps and approaches. [ABSTRACT FROM AUTHOR]

For the transition to sustainable energies to happen in a relatively safe manner, there has to be as many improvements to actual capabilities that allows us to convert solar and wind energy into electric energy. For this reason, in this paper, we present a potential solution to rise the efficiency of solar irradiation conversion by using a cheap, highly reflective membrane under the already installed solar arrays. This solution can be used in order to maximize the radiation that falls on the photovoltaic cell, especially under the panel, by using bifacial photovoltaic panels. [ABSTRACT FROM AUTHOR]

Bifacial perovskite solar cells (PSCs) have accentuated a great deal of attention to achieve a higher power output per unit area by utilizing albedo compared to conventional monofacial solar cells with a very low additional manufacturing cost. However, the design of the bifacial PSCs is very much challenging due to high rear side carrier recombination, ion migration, and electrode corrosion as well as electrical loss in transparent rear contact. In this paper, we have reviewed bifacial PSCs to explore and analyze their latest advancement. The bifacial device's performance varies with respect to the albedo from where the diffuse light gets reflected to the rear side which has also been discussed thoroughly. For the best performance of bifacial solar cells, the back contact electrode, transport layer, and perovskite layer of the device need to be transparent, for which various ways to make components semi-transparent have been discussed and explored. The transparent charge carrier layer helps in reducing the parasitic recombination, which directly affects the bifacial photoconversion efficiency. This extensive review of bifacial PSCs is presented here which will guide perovskite research for feasible commercial realization. [ABSTRACT FROM AUTHOR]

Degradation from ultraviolet (UV) radiation has become prevalent in the front of solar cells due to the introduction of UV‐transmitting encapsulants in photovoltaic (PV) module construction. Here, we examine UV‐induced degradation (UVID) in various commercial, unencapsulated crystalline silicon cell technologies, including bifacial silicon heterojunction (HJ), interdigitated back contact (IBC), passivated emitter and rear contact (PERC), and passivated emitter rear totally diffused (PERT) solar cells. We performed UV exposure tests using UVA‐340 fluorescent lamps at 1.24 W·m−2 (at 340 nm) and 45°C through 4.02 MJ·m−2 (2000 h). Our results showed that modern cell architectures are more vulnerable to UVID, leading to a significant power decrease (−3.6% on average; −11.8% maximum) compared with the conventional aluminum back surface field (Al‐BSF) cells (<−1% on average). The power degradation is largely caused by the decrease in short‐circuit current and open‐circuit voltage. A greater power decrease is observed in bifacial cells with rear‐side exposure compared with those with front‐side exposure, indicating that the rear side is more susceptible to UV damage. Secondary ion mass spectroscopy (SIMS) confirmed an increase in hydrogen concentration near the Si/passivation interface in HJ and IBC cells after UV exposure; the excess of hydrogen could result in hydrogen‐induced degradation and subsequently cause higher recombination losses. Additionally, surface oxidation and hot‐carrier damage were identified in PERT cells. Using a spectral‐based analysis, we obtained an acceleration factor of 5× between unpackaged cells (containing a silicon nitride antireflective coating on the front) in the UV test and an encapsulated module (with the front glass and encapsulant blocking 90% of the UV at 294 nm and 353 nm, respectively) in outdoor conditions. From the analytical calculations, we show that a UV‐blocking encapsulant can reduce UV transmission in the module by an additional factor of ~50. [ABSTRACT FROM AUTHOR]

Brazil's cumulative photovoltaic (PV) installations have now surpassed 32 GWp. The fastest growing and most prevalent PV technology is the bifacial photovoltaic module, which is now being incorporated in more than 2/3 of new power plants. These modules collect solar radiation on both front and rear sides, providing gains in electricity production compared to traditional monofacial modules. The market acceptance and quality control of this technology requires standard methods to accurately determine the nominal power of the bifacial modules. But the specification of energy production from the bifacial backside is complicated due to critical factors that include the albedo, the separation, height, and positioning of the modules, the shading of the rear surface, and the specific geographic and climate conditions. This paper addresses these issues in determining the performance of bifacial PV modules in the tropical conditions of the State of Minas Gerais, Brazil. Specifically, the bifacial gain for modules and systems is evaluated, assessing the effects of albedo, site maintenance, climate/environmental conditions, thermal behavior, and back-surface shading. The special cases of tracking versus non-tracking systems are evaluated showing specific attention needs to the albedo changes and rear module shading constraints. These studies are performed on real power plants having different operating conditions (e.g., tracking, non-tracking, ground cover). The methodology includes I-V characterization of modules and string and thermal imaging/mapping under existing climate and meteorological conditions. Correlations with experimental albedo conditions is a special concern with these studies. These results are further compared to controlled laboratory measurements to establish information needed to better evaluate the developing standard for actual local operating conditions. This case study provides evaluation of the quality of the both the bifacial PV products being used and their installations in the rapidly emerging Brazil PV markets. [ABSTRACT FROM AUTHOR]

Bifacial technology is attracting the attention of the photovoltaic community. Although considered premature, research and development activities still need to be carried out to improve bPV performance. In addition, the need for a standard test reference will aid bankability and increase confidence in this technology. This article describes the state of the art of bifacial technology, going through the bPV cell and its difference compared to conventional monofacial cells and listing the different sources of limitations, with an identification of different parameters that characterize the performance of the bifacial. Then, the paper reviews the different modeling methods that allow predicting the performance of bPV systems, and ends with the most important applications, whether for dual use of land to produce energy and food (agrivoltaic) or for placing bPV modules on water bodies instead of on the ground (aquavoltaics), or for vertical use as solar fences, acoustic barriers, or building-integrated photovoltaic modules. [ABSTRACT FROM AUTHOR]

Glass/glass (G/G) photovoltaic modules are quickly rising in popularity, but the durability of modern G/G packaging has not yet been established. In this work, we examine the interfacial degradation modes in G/G and glass/transparent backsheet modules under damp heat (DH) with and without system bias voltage, comparing emerging polyolefin elastomer (POE) and industry‐standard poly(ethylene‐co‐vinyl acetate) (EVA) encapsulants. We investigate the transport of ionic species at cell/encapsulant interfaces, demonstrating that POE limits both sodium and silver ion migration compared with EVA. Changes to the chemical structures of the encapsulants at the cell/encapsulant interfaces demonstrate that both POE and EVA are more susceptible to degradation in modules with a transparent backsheet than in the G/G configuration. Adhesion testing reveals that POE and EVA have comparable critical debond energies after the DH exposures regardless of system bias polarity. The results of this study indicate that the interfacial degradation mechanisms of G/G appear to be similar to those of conventional glass/backsheet modules. For emerging materials, our results demonstrate that POE offers advantages over EVA but that transparent backsheets may accelerate encapsulant degradation due to increased moisture ingress when compared with the G/G structure. [ABSTRACT FROM AUTHOR]

Desert environments exhibit high soiling rates that have a profound impact on the energy yield and the operations and maintenance of Photovoltaic (PV) power plants. This study investigates vertical east–west (Vertical) installation of bifacial PV modules in desert climates − its effectiveness in energy generation and as a mitigation strategy for PV soiling. To assess the impact of module bifaciality and orientation on energy yield and soiling, we compared the performance of latitude-tilted, i.e. 22° facing South (Tilted) bifacial and monofacial, and the vertical bifacial PV modules under real outdoor desert climatic conditions of Qatar. Our findings demonstrate that the vertical installation configuration presents an appealing alternative for energy production and holds great potential as a solution for mitigating soiling in desert climates. Over the study period, clean tilted bifacial modules produced approximately 4.0% more energy than clean vertical modules, on average. However, the tilted modules experienced substantial and progressive soiling losses, reaching up to 60% for monofacial modules. Although the losses for bifacial modules were also high, they were about 15% lower than those of monofacial modules. Additionally, during the summer months, when the sun's path is higher in the sky, vertical bifacial modules generated 3.8% in average, and up to 9.2% more energy than the tilted modules. The results demonstrate that bifacial PV reduces the impact of PV soiling and the vertical module installation shows strong potential as an effective approach for energy production and combating PV module soiling in desert climates with high natural ground albedo. [ABSTRACT FROM AUTHOR]

The bifacial photovoltaics (PV) technology promises several advantages over monofacials, including improved energy yield, lower operating temperature, and easier integration with agrophotovoltaics. There have been various experimental or computational studies comparing bifacials to monofacials; however, a theory-experiment combined analysis for accurate worldwide extrapolation is missing. Literature review reveals that many reported experiments study standalone systems that overrepresent the yield performance obtainable in farms. Moreover, most reported experimental studies are for configurations that are not necessarily designed close to the optimum. In this work, we experimentally study and analyze the fixed-tilted bifacial farm configiurations, namely south-facing monofacial, south-facing tilted bifacial (TBF), and ground-sculpted vertical bifacial (VBF) arrays, at Dhaka, Bangladesh (23.7 °N, 90.4 °E). The optimal TBF configuration, for 0.5 albedo, yields 21.3% and 73.3% more than the optimal monofacial and the optimal VBF configurations, respectively. Through a combination of experimental and numerical analysis, we compare the in-array performance of the configurations under different albedo conditions to analyze the physics and consolidate the predictions. There is a growing interest in PV array configurations beyond the conventionally ground-mounted south-facing TBF, such as agrophotovoltaics, floating-PV, industry-roof PV array, etc. This necessitates a critical analysis of various array configurations for broader PV expansion.

• The spectral behaviour of both front and rear sides of bifacial modules is analysed. • A bifacial spectral factor is proposed to assess the combined front and rear impact. • The model considers the impact of module-to-ground clearance and bifaciality. • Spectra of three cities and four grounds are modelled with SMARTS and AERONET data. • The bifacial spectral factor on green grass is up to 1.65% higher than for monofacial. The demand for bifacial photovoltaic modules is continuously increasing. However, some aspects of their behaviour under realistic operating conditions still require more in-depth investigations. Indeed, the long-term analysis of the spectral impact on bifacial modules remains pending. This is particularly true for the rear incident spectrum, which changes depending on the ground type. In this paper, the rear and front long-term spectral impact on bifacial modules is analysed for three locations (Tabernas, Spain; Solar Village, Saudi Arabia; Alta Floresta, Brazil) and four ground types (light soil, white sand, green grass, and concrete slab) at daily, monthly and annual timescales. The SMARTS model is used to generate front and ground-reflected annual spectra. The investigation leads to the definition of a novel metric, called bifacial spectral factor, which quantifies the combined front and rear spectral impact. Results show that the annual bifacial spectral impact differs from the monofacial one due to the influence of the rear spectral irradiance. Green grass is found to have the higher bifacial spectral benefit, leading to yields in between 1.19% and 1.65% higher than in the monofacial case. However, thanks to its high albedo coefficient, white sand is the most convenient ground among the analysed types in terms of bifacial spectral energy gains. The rear spectral factor shows a great range of variation as a function of ground type (between 0.989 and 1.150). However, this is only a non-negiglible second order effect compared to the bifacial spectral factor, which is mainly influenced by the front spectral factor. [ABSTRACT FROM AUTHOR]

A double-sided solar cell (a bifacial photovoltaic (PV) cell arrangement) consisting of two back-to-back silicon photovoltaic cells is examined in this paper, and compared with a Monofacial cell. It was installed on a two-axis solar tracker. Temperature and radiation were monitored on sunny noonday in El-Marg city, Libya. The purpose of this investigation is to demonstrate the generation and matching of bifacial solar cells made by back-stacking two monoclinic solar cells. The face in the front accepts direct solar radiation, while the face in the back accepts indirect solar radiation that is reproduced from the ground, clouds, and surrounding buildings. The chief focus is on determining how ambient temperature affects the performance of bifacial photovoltaic panels. On two hot summer days in Al-Marg city, important photovoltaic parameters of the binary system (short-circuit photocurrent density, open circuit photovoltaic voltage, maximum power conversion efficiency) was verified. The PV performance of each individual cell shows remarkable variability with the movement of the tracer to the effect of radiation and the surface temperature of each cell. The results showed that the back cell performs better than the front cell. Although the back cell was exposed to fewer illuminations, it provided the front with higher power conversion efficiency than the front cell. [ABSTRACT FROM AUTHOR]

The major challenge of PV cell design and installation has always been to find the optimum cost per energy and area of installation of solar panels. In densely populated and high-yielding agricultural country like India land acquisition is becoming an issue. Moreover the consisting demand to deduce the cost per energy indulges the worldwide scientists to design more efficient solar cells with low production cost. In developing countries scientists and engineers are trying to find an amicable solution to meet up these problems. In this paper the mathematical modelling of a dual SIS bifacial vertically mounted solar panel has been proposed to mitigate the energy and land area crisis in countries of Indian subcontinent, south Asia and elsewhere. The SIS (Semiconductor-Insulator-Semiconductor) technology was chosen for its extremely low thermal budget and less complicated production procedure. A bifacial solar cell with SIS junction in both sides was modelled. The front surface SIS junction was considered ZnO-SiO2-Si(p-type) while the back surface junction was considered Si(p type)-Al2O3-SnO. The efficiency for front and back surface was calculated as 5.64% and 5.58% respectively. We have further considered the effect of albedo from two different surfaces (soil and concrete) and the efficiencies of front and back surface for these albedo radiations. The angle of installation was optimized for both these effects. Considering both direct and albedo the all-day efficiency was calculated as 22.47% for a sunny day tropical region. [ABSTRACT FROM AUTHOR]

Motivated by the rapidly rising deployment of bifacial monocrystalline‐silicon photovoltaics (PV), we investigate the durability of various PV module packaging configurations with transparent coverings on both the front and rear sides of the module. We use a series of bifacial passivated emitter and rear cell (p‐PERC) mini‐modules with systematically varying outer cover materials (glass/glass, G/G, or glass/transparent backsheet, G/TB) and encapsulant chemistries (poly [ethylene‐co‐vinyl acetate], EVA; or polyolefin, POE). We study degradation modes over 1,000 hours of combined damp heat (DH) exposure and high system voltages that can cause potential‐induced degradation (PID) under positive, zero, or negative 1,000 V cell‐to‐frame bias. We analyze the degradation modes using a combination of current–voltage measurements, impedance spectroscopy, external quantum efficiency, and spatially resolved luminescence and thermal imaging. Our results highlight various types of degradation including shunting, enhanced recombination, and series resistance increases, and we use spatially resolved characterization to separately identify the localized effects. We show that multiple PID and moisture‐ingress degradation modes severely affect EVA‐containing modules, with previously reported PID processes under negative‐bias DH and a unique observation of rear‐side surface recombination in G/EVA/G modules under positive‐bias DH. We observe significantly less degradation in POE‐containing modules, where the G/POE/G configuration exhibits minimal degradation under all stress conditions that we employ. [ABSTRACT FROM AUTHOR]

In this work, a simple, compact, and accurate model for PV is introduced. The introduced model used the five-parameter approximation that accounts for both irradiance and temperature variations. The introduced model studied the effect of semiconductor parameters such as doping level, electron, and whole mobilities. The model is verified experimentally using electronic power load at different levels of irradiance and temperature. Also, an integrated module using Simulink simulation is introduced of about 1% error compared to the experimental results. In this work, we used four different PV modules to verify the introduced model. The model accuracy of the proposed reaches 0.85% at different levels of temperature and irradiance of 1000 W/m2. [ABSTRACT FROM AUTHOR]

The performance of bifacial Cu(In,Ga)Se 2 (CIGS) cells does not yet reach the one of monofacial cells, with standard Mo rear contacts. By exploring optoelectronic simulations, this study addresses the impact of a transparent conducting oxide layer used as rear contact in CIGS solar cells. These simulations, which aim to create a digital twin of bifacial CIGS solar cells, offer insight into the impact of novel rear contact architectures. It was observed that with an indium tin oxide (ITO) rear contact the CIGS cell performance lacks in comparison to a Mo one due to an electrical barrier, under rear side illumination these devices may only reach 3.9 % in conversion efficiency. The implementation of dielectric rear passivation schemes have great performance benefits in cells with Mo rear contacts. Therefore, the same passivation strategy in ITO contacts is discussed and additional novel architectures are proposed, from which a design of alternated lines between dielectric and 15 nm Mo layers on ITO showed promising results. Such rear architectures aim to achieve i) a highly transparent rear contact, ii) an ohmic-like behaviour with CIGS, and iii) a low defective interface with rear passivation. The selenization of the complete 15 nm Mo in the proposed novel architecture during the CIGS growth was considered, resulting in transmittance values above 70 % and, notably, reaching the transparency of bare ITO in the infrared range. Such rear architecture may provide for bifacial CIGS solar cells with conversion efficiency values surpassing 20 and 15 % for front and rear side illumination, respectively, allowing to fully exploit bifaciality. [Display omitted] • Optoelectronic simulations on bifacial CIGS solar cells with novel architectures. • Rear dielectric passivation does not have great benefits on TCO rear contacts. • Novel rear architectures required to reach performance of standard Mo. • 15 nm Mo patterned with dielectric layer: high transparency; ohmic; low defects. • At least 20 and 15 % front and rear illumination conversion efficiency, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • Spectral vs absolute raw data: solar irradiance, reflectivity, and solar cell spectral 2 response. • Dynamic crop growth cycle optical properties influencing agrovoltaic systems. • Bifacial PV module performance as function of geometry, ground and solar irradiance 5 components. • Accurate predicted photocurrent in bifacial agrovoltaic systems. This research delves into the nuanced dynamics influencing photocurrent generated in bifacial photovoltaic modules within the framework of agrovoltaic applications. Our findings underscore the necessity of using spectral data over absolute values regards to the wavelength dependence for precise energy yield predictions. Particularly, it is demonstrated that the ground reflectance plays a pivotal role. The type of soil (compact or tilled) and crop growth cycle contribute to temporal variations, significantly affecting energy production. In order to validate the proposed methodology for estimating photocurrent generated by APV systems based on spectral data, we conducted tests in two different irradiance conditions, deliberately chosen for their contrast: clear sky and hazy sky conditions. Experimental measurements were conducted for global, direct, and diffuse irradiance spectral components in both atmospheric scenarios. Additionally, we performed comprehensive spectral reflectance measurements for various soil types and crops throughout an entire growth cycle to depict the temporal variations in these values. It is observed an overestimation in the ratio between front and rear photocurrent generated by the bifacial PV module when the model relies on absolute values of solar irradiance and ground reflectance, compared to utilizing spectral input data. Furthermore, the analysis of absolute values fails to reveal a significant dependence on atmospheric conditions. In summary, this research discussed the implications of spectral data, geometry and atmospheric conditions, for bifacial PV modules in agrovoltaic applications. [ABSTRACT FROM AUTHOR]

Conventional assessment methods of albedo measurement, like satellite imagery and on-site single-point measurements, lack the precision to address surface textural variances that can lead to power mismatches in a string of bifacial photovoltaic modules (BF-PV). To overcome this, we propose an innovative solution — an autonomous rover equipped with back-to-back pyranometers on its arm to measure the upward (plane-of-array) and downward (albedo) irradiance of a given surface. Employing an efficient path-planning algorithm, the rover ensures comprehensive spatial albedo data collection, overcoming the limitations of existing methods. The paper details the verification of the proposed methodology, its efficacy, and its importance over traditional approaches. This system enables holistic spatial albedo mapping of large areas, capturing textural/topographical non-uniformity, which is crucial for BF-PV installations. Simulations are conducted at the MBR Solar Park in Dubai, UAE, using albedo values measured and collected by the rover. The simulations involved calculating power output for a string of 20 modules across three cases of spatial albedo variations (0.32–0.38, 0.329–0.330, and 0.12–0.36). In the worst-case scenario (case 3), a power mismatch of 18.7% across the module string and a 4.2 °C temperature mismatch are observed. Cases 1 and 2 showed 4.6% and 0.2% power mismatch losses, respectively. These results underscore the critical role of precise spatial albedo measurements in optimizing installation conditions, emphasizing the need for spatial mapping to enhance energy yield estimates. • Developed a new methodology for spatial albedo mapping using a rover. • Highlighted importance of non-uniform spatial albedo on bifacial PV. • A novel albedo-map of an area of 1 sq. km to visualize topographical variation. • Power mismatch of 18.7% for a string of 20 modules when albedo variation is within 0.12–0.36. • Precise estimate for bifacial PV plant installation. [ABSTRACT FROM AUTHOR]

Summary: The idiosyncrasy of bifacial photovoltaic devices by means of its ambivalent nature in absorbing irradiation demarcates this technology from conventional monofacial modules. The performance of bifacial PV devices is primarily a function of the orientation of the device, that is, its tilt angle (β), the elevation of the module above the ground (E), the albedo of the location (ρg) and the azimuth angle (γ). The current work, focusing on determining the optimum setting for module installation, takes into consideration three factors, namely, β°, E(m) and γ°, concentrated on maximizing the power generation from the test bifacial PV module at Jaipur, India (26.91°N, 75.78°E) using full factorial design experiment through Taguchi method. Based on Taguchi analysis, the optimal parameter setting for maximizing response obtained is β° = 40°, E = 0.8 m and γ° = 22.5°. Adequacy of the design was determined through ANOVA, which presented a high R2 value of 88.7%. The results for optimal parameter setting obtained using Taguchi design are validated through experiment, and the error in computed value and experimentally determined value of response is 2.64%. The PR of the module installed at optimum orientation, upon investigation, was highest among test orientations (84.76%) due to greater rear side irradiance collection. Further results show that increasing albedo increases the output for modules installed at optimum orientation. The results are also verified against empirical relations presented in the literature to highlight the competency of the results. [ABSTRACT FROM AUTHOR]

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• The extent to which bifacial spectral effects are dependent on the albedo, sky conditions, and mounting structure are quantified. • Backside spectral mismatch can be reasonably approximated using spectral albedo measurements with just 5–8 narrow band channels. • The normalized difference vegetation index is a good predictor of the backside spectral effects present in bifacial systems. • An open access spectral dataset consisting of spectral albedo, spectral global horizontal irradiance, and spectral beam measurements is made freely available. This paper analyzes 15-months of spectral albedo measurements collected at the Technical University of Denmark (55.6°N, 12.1°E). High-resolution spectroradiometers are used to monitor four albedo scenarios, which include green vegetation, dry vegetation, gravel, and snow. Spectral mismatch and spectral impact are calculated for the front and backside of three different bifacial cell concepts mounted on horizontal single axis trackers and fixed-tilt substructures. The spectral nature of albedo is shown to have significant influence on bifacial photovoltaic performance wherein backside spectral impact as high as 1.20 is observed for fixed-tilt systems above green vegetation and as low as 0.98 for systems above snow. The results reveal that spectral impact is always lower on tracked than fixed-tilt systems because a greater fraction of sky diffuse light reaches the backside of tracked systems. Given the variety of albedos tested here, we find that the normalized difference vegetation index is a good predictor of backside spectral effects. When the high-resolution measurements are truncated to 4 to 8 carefully selected wavelengths, we find that this limited measurement resolution sufficiently captures the seasonal spectral albedo fluctuations that influence bifacial photovoltaic energy production. Finally, to alleviate the dearth of spectral datasets presently available to the PV community, the spectral irradiance and albedo measurements are made freely available in open access format (https://doi.org/10.11583/DTU.14695437.v1). [ABSTRACT FROM AUTHOR]