Search

With the rapidly growing interest in bifacial photovoltaics (PV), a worldwide map of their potential performance can help assess and accelerate the global deployment of this emerging technology. However, the existing literature only highlights optimized bifacial PV for a few geographic locations or develops worldwide performance maps for very specific configurations, such as the vertical installation. It is still difficult to translate these location- and configuration-specific conclusions to a general optimized performance of this technology. In this paper, we present a global study and optimization of bifacial solar modules using a rigorous and comprehensive modeling framework. Our results demonstrate that with a low albedo of 0.25, the bifacial gain of ground-mounted bifacial modules is less than 10% worldwide. However, increasing the albedo to 0.5 and elevating modules 1 m above the ground can boost the bifacial gain to 30%. Moreover, we derive a set of empirical design rules, which optimize bifacial solar modules across the world and provide the groundwork for rapid assessment of the location-specific performance. We find that ground-mounted, vertical, east-west-facing bifacial modules will outperform their south-north-facing, optimally tilted counterparts by up to 15% below the latitude of 30°, for an albedo of 0.5. The relative energy output is reversed in latitudes above 30°. A detailed and systematic comparison with data from Asia, Africa, Europe, and North America validates the model presented in this paper. [ABSTRACT FROM AUTHOR]

• A new perspective on LCOE that decouples cost and performance of solar farms. • Optimization of solar farm design using essential Module to Land cost ratio (M L). • Modeling of direct, diffuse, and albedo light collection for tilted bifacial PV. • 2–6% reduction in LCOE for bifacial over monofacial PV farm for |latitude| > 30°. • Global maps, opportunities, and challenges for bifacial vs. monofacial PV farm. The steady decrease in the levelized cost of solar energy (LCOE) has made it increasingly cost-competitive against fossil fuels. The cost reduction is supported by a combination of material, device, and system innovations. To this end, bifacial solar farms are expected to decrease LCOE further by increasing the energy yield; but given the rapid pace of design/manufacturing innovations, a cost-inclusive optimization of bifacial PV systems at the farm-level (including land costs) has not been reported. In our worldwide study, we use a fundamentally new approach to decouple energy yield from cost considerations by parameterizing the LCOE formula in terms of "land-related cost" and "module-related cost" to show that an interplay of these parameters defines the optimum design of bifacial farms. For ground-mounted solar panels, we observe that the panels must be oriented horizontally and packed densely for locations with high "land-related cost", whereas the panels should be optimally tilted for places with high "module-related cost". For systems with relatively high "module-related costs" and for locations with |latitude| > 30°, the bifacial modules must be tilted ∼10°–15° higher and will reduce LCOE by 2–6% compared to their monofacial counterparts. The results in this paper will guide the deployment of LCOE-minimized ground-mounted tilted bifacial farms around the world. [ABSTRACT FROM AUTHOR]

Nowadays, a significant number of distribution systems are facing problems to accommodate more photovoltaic (PV) capacity, namely due to the overvoltages during the daylight periods. This has an impact on the private investments in distributed energy resources (DER), since it occurs exactly when the PV prices are becoming attractive, and the opportunity to an energy transition based on solar technologies is being wasted. In particular, this limitation of the networks is a barrier for larger consumers, such as commercial and public buildings, aiming at investing in PV capacity and start operating as microgrids connected to the MV network. To address this challenge, this paper presents a coordinated approach to the microgrid investment and planning problem, where the system operator and the microgrid owner collaborate to improve the voltage control capabilities of the distribution network, increasing the PV potential. The results prove that this collaboration has the benefit of increasing the value of the microgrid investments while improving the quality of service of the system and it should be considered in the future regulatory framework. [ABSTRACT FROM AUTHOR]

• Global yield potentials of fixed tilt and tracking solar farms employing bifacial two-terminal tandem are quantified. • Effective albedo collection determines the relative performance gain of bifacial 2T tandem systems. • Only 3.5–5% gains at optimal albedo conditions are expected worldwide compared to constituent single junction HIT subcell. • Deviation of effective albedo from 2T tandem's design albedo erases the gain in yield potential owing to current-matching. The bifacial gain of various optimally-tilted, and tracking bifacial farms based on single-junction PERC and HIT technologies are well established. The solar module technology is, however, evolving rapidly with the commercial development of two, three, and four-terminal mono and bifacial HIT-Perovskite tandem cells underway. Given the complexity of current-matching in two-terminal tandem cells and significant variation of the weather conditions across the world, one wonders if the benefits of fixed-tilt and tracking cells obtained for single-junction solar cells would remain for tandem solar cells. In this paper, we use a detailed illumination and temperature-dependent bifacial solar farm model (supported by a detailed physical model for bifacial HIT-Perovskite tandem cells) to show that (a) row-to-row shading in solar arrays significantly suppresses the effective albedo collection and thereby the two-terminal (2T) tandem cell efficiency and relative gain compared to an optimal bifacial HIT cell, (b) the global energy yield potential of fixed-tilted and solar-tracking topologies would improve by adopting a 2T tandem design at optimal albedo, with maximum gain arising for tracking farms, (c) the 2T tandem cell/modules (subcell bandgaps, thickness) must be optimized for maximum benefit, and (d) even a relatively small deviation from the optimum will negate all benefits. Our results will broaden the scope and understanding of the emerging tandem bifacial technology by demonstrating global trends in energy gain for worldwide deployment and the need for location-specific tailoring of the module design. [ABSTRACT FROM AUTHOR]

The substantial increase in deployment of customer-sited solar photovoltaics (PV) in the United States has been driven by a combination of steeply declining costs, financing innovations, and supportive policies. Among those supportive policies is net metering, which in most states effectively allows customers to receive compensation for distributed PV generation at the full retail electricity price. The current design of retail electricity rates and the presence of net metering have elicited concerns that the possible under-recovery of fixed utility costs from PV system owners may lead to a feedback loop of increasing retail prices that accelerate PV adoption and further rate increases. However, a separate and opposing feedback loop could offset this effect: increased PV deployment may lead to a shift in the timing of peak-period electricity prices that could reduce the bill savings received under net metering where time-varying retail electricity rates are used, thereby dampening further PV adoption. In this paper, we examine the impacts of these two competing feedback dynamics on U.S. distributed PV deployment through 2050 for both residential and commercial customers, across states. Our results indicate that, at the aggregate national level, the two feedback effects nearly offset one another and therefore produce a modest net effect, although their magnitude and direction vary by customer segment and by state. We also model aggregate PV deployment trends under various rate designs and net-metering rules, accounting for feedback dynamics. Our results demonstrate that future adoption of distributed PV is highly sensitive to retail rate structures. Whereas flat, time-invariant rates with net metering lead to higher aggregate national deployment levels than the current mix of rate structures (+5% in 2050), rate structures with higher monthly fixed customer charges or PV compensation at levels lower than the full retail rate can dramatically erode aggregate customer adoption of PV (from −14% to −61%, depending on the design). Moving towards time-varying rates, on the other hand, accelerates near- and medium-term deployment (through 2030) but slows adoption in the longer term (−22% in 2050). [ABSTRACT FROM AUTHOR]

[Display omitted] • A directly solar-driven power-to-methane system is proposed. • The detailed distributed parameter method is used to model the system. • A comprehensive thermodynamic and economic analysis is performed. • Energy and exergy efficiencies are 9.88% and 11.08% with 914.51 MWh/y SNG yield. • Unit cost is 186.57 $/MWh in 2020 and will be reduced to 91.51 $/MWh in 2050. The transformation of solar energy into easily transportable and storable fuel brings a prospective solution to the issue caused by its intermittency and non-dispatching. Relying on well-established infrastructures and mature technologies for application, methane can be an attractive energy carrier for improving the penetration of solar energy in the future energy structure. To evaluate the feasibility of solar-to-methane from technical and economic views, this paper proposes a directly solar-driven power-to-methane system integrating photovoltaic plant, solid oxide electrolysis cell, methanation reactor, and membrane module. The detailed distributed parameter method is employed for thermodynamically modeling the core components of the system to consider the profiles of current density, temperatures, and composition concentrations. A comprehensive thermodynamic and economic analysis is further conducted for the system, and the results indicate that the power-to-methane efficiency, total energy efficiency, and total exergy efficiency of the system can reach 68.41%, 9.88%, and 11.08%, respectively. With the annual average solar radiation of 557.43 W/m2, the system achieves an annual synthetic natural gas yield of 914.51 MWh/y. A high total product unit cost of 186.57 $/MWh is obtained in 2020, whereas it is predicted to decrease to 91.51 $/MWh (about 51% reduction) in a future scenario with a payback period of 4.66 years due to the significant decrement of the photovoltaic investment cost. The present work reveals the engineering realizability and economic viability of solar-to-methane and provides a competitive option for the development of solar energy. [ABSTRACT FROM AUTHOR]

• MERRA-2 outperforms CAMS in capturing seasonal dust, consistent with Himawari-8 observations. • Dust emissions and depositions in Australia peak at 1.4 gm−2 during Spring-Summer. • Seasonal soiling show reductions in energy of ∼3% near the Lake Eyre Basin. • Rainfall bursts remove soiling of 3 gm−2 at solar farms, improving energy yield by 9%. Dust plays a vital role in the Earth's climate system and can also modulate solar energy yield from photovoltaics due to soiling and it also impacts concentrated solar power outputs by up to 30%. Research examining decreased energy production on solar panels due to dust accumulation is limited. This is particularly important for dry arid regions of Australia, which are prone to dust storms. Thus, this paper examines the dust characteristics over Australia by comparing two reanalysis products, the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2) and the Copernicus Atmosphere Monitoring Service (CAMS) with the satellite data (Himawari-8) to ascertain the capabilities of the reanalysis products in capturing dust cycles over Australia. The results are then used to explore the seasonal variability and trends in the radiative impacts, emissions, and depositions of dust. The energy reductions from seasonal averaged dust accumulations without natural removal or cleaning and later the impact of soiling with removal from precipitation bursts on selected operational solar farms are presented. Results show that MERRA-2 outperforms CAMS in capturing Dust Aerosol Optical Depth (AOD) near the Lake Eyre Basin in all seasons, consistent with satellite observations. The radiative trends showed contrasting differences during the Spring and Summer, whereas seasonal dust emissions and depositions peaked at 1.4 gm−2. Similarly, seasonal dust accumulations without natural removal on panels showed significant reductions in the energy of up to 3% around the Lake Eyre Basin, but most operational solar farms in Australia depicted energy reductions of 8–9% due to accumulated dust of up to 2.5–3 gm−2, which was naturally removed from regular seasonal rainfall bursts. [ABSTRACT FROM AUTHOR]

• Non-uniform illumination combined with full-cell model to find hourly energy output. • A clear understanding of installed parameters, climate, and module factors dependence. • A new set of fits that decouple mismatch loss and configurations of bifacial PV farms. • The rapid estimation of mismatch loss shows a better goodness, especially in high-mismatch conditions. • More detailed bifacial gain mapping for geography-specific bifacial modules. The effective cost reduction of solar photovoltaic (PV) power generation systems is supported by the widespread use of bifacial modules. To this end, the multiple bifacial modellings are expected to measure the energy yield excluding the mismatch power loss induced by self-shading. But, given the magnitude of non-uniform irradiance may differ between the monofacial and bifacial modules, the conventional full cell-level electrical model is no longer suitable for fast-estimation of bifacial ones. Hence, a fundamentally new equation is reformulated by parameterizing rear-shading mismatch losses (ML) optimally as a function of irradiance variability (standard deviation σ), whereby implicitly taking the effect of rear-shading into account. In Taizhou, the annual ML is found to be as high as 0.8% for close mounts (0.2 m) with a 0.2 albedo and a 22° tilt angle. Panels fixed with or without torque tube have been compared numerically. After the hourly rear-inhomogeneity and configuration dependence on cumulative annual ML of several global-mounted bifacial modules were analyzed. The authors improved the fit with an R2 better than 0.9 for generalization to any worldwide scenarios. Both experimental results and inter comparison with prior empirical equations indicate a better goodness of fits, especially in high-mismatch conditions. In this paper, the presented mismatch model will guide the deployment of revised bifacial gain (BG r)-maximized bifacial systems around the world. [ABSTRACT FROM AUTHOR]

• Temperature-dependent energy-yield (YY) and LCOE favor bifacial over monofacial PV. • An irradiance criterion defines the necessary condition for positive bifacial gain. • T-dependent vs. STC energy-yield change: (−7, 12)% for Al-BSF and (−5, 5)% for SHJ. • Global bifacial energy gain for SHJ (bi) vs. Al-BSF (mono) ranges from 12 to 45%. • YY saturates at elevation ~2 m with a global gain of 0–20% over unelevated farms. Bifacial solar panels are perceived to be the technology of choice for next-generation solar farms for their increased energy yield at a marginally increased cost. As the bifacial farms proliferate around the world, it is important to investigate the role of temperature-dependent energy-yield and the levelized cost of energy (LCOE) of bifacial solar farms relative to monofacial farms, stand-alone bifacial modules, and various competing bifacial technologies. In this work, we integrate existing irradiance and light collection models with experimentally validated physics-based temperature-dependent efficiency models to compare the energy yield and LCOE of various bifacial technologies across the world. We find that temperature-dependent efficiency changes the energy yield and LCOE by approximately - 10 t o 15 %. Indeed, the results differ significantly depending on the location of the farm (defines the illumination and ambient temperature), the elevation of the module (increases light collection), as well as the temperature-coefficients of various bifacial technologies. The analysis presented in this paper will allow us to realistically assess location-specific relative advantage and economic viability of the next generation bifacial solar farms. [ABSTRACT FROM AUTHOR]

Storage coupled solar photovoltaic systems have gained traction in recent years due to a) advancements in battery storage technologies and b) decreasing system costs. The viability and optimum operation of these systems is typically studied for building(s) in isolation or with grid interactions. In this paper a grid-interactive photovoltaic-storage system in a multi building scenario with net-metering is evaluated. A simulation model is developed for an interconnected multi building environment with a primary building owning the photovoltaic-battery system. The optimization model is formulated as a mixed integer linear programming problem and is solved in ILOG optimization studio with CPLEX solver. Multiple secondary buildings can procure power from the primary building based on suitable bilateral contracts. The applicability of the model is demonstrated through real-time load demand of three buildings along with actual time-of-use pricing data from the utility in the city of Auckland, New Zealand. The results provide an insight on the financial gains of installing rooftop photovoltaic-battery systems at buildings with power trading agreements under time-varying electricity tariffs. The detailed results from the model signify that primary building (with solar and storage) earns up to 43% of annual profits after incorporating installation costs of photovoltaic-battery system. Further, secondary buildings (without solar or storage) achieve 3–16% of savings in the electricity costs based on different contracted loads and agreement tariffs. This work can further enhance the utilization of solar energy resource via rooftop solar photovoltaic to help mitigate the per capita carbon dioxide emissions in countries with high dependency over fossil fuel for electricity generation. [ABSTRACT FROM AUTHOR]