Repowering photovoltaic (PV) systems is often perceived as an economically driven process, yet our research reveals a more complex reality. Through expert interviews and case studies, we demystify the motives behind repowering, showing that currently actions are driven by repairs or system unreliability rather than financial considerations. We clarify repowering definitions and provide real-world insights. Using economic analyses with the System Advisor Model (SAM), we evaluate the net present value (NPV) and payback time of repowering scenarios, with further analyses into mass, energy, and other impacts, highlighting key barriers and benefits. By clarifying definitions and providing real-world insights, this work lays a foundation for understanding how to make repowering decisions effectively.
ReMade@ARI (remade-project.eu) is a European project offering access to large-scale analytical infrastructures for research in the field of Circular Economy. Access is offered free of charge to users from academia and SMEs, and travel support is available. ReMade@ARI includes more than 50 infrastructures from 6 networks with corresponding analytical probes: e-DREAM for electron microscopes, Laserlab-Europe for laser light sources, LEAPS for synchrotron radiation and free electron lasers, RADIATE for ion beams, LENS for neutron sources, and EMFL for high magnetic fields as well as various other probes including positrons. Twice per year, ReMade@ARI opens a call for proposals for users from the entire world (not limited to Europe). The evaluation criteria of proposals include (1) scientific excellence and methodology, (2) circular economy relevance, (3) novelty and interdisciplinary, (4) commercial impact. Proposals requesting simultaneously multiple techniques are given priority. The proposals are handled by a dedicated ReMade@ARI user office, and a single proposal for multiple techniques replaces the traditional facility-specific proposals. Beyond instrument access, ReMade@ARI offers extensive scientific support through the Smart Science Cluster: a team of 18 Junior Scientists offers one-to-one support to users from writing proposals to conducting experiments and analyzing data. This tailored scientific support enables researchers that may be new to large-scale facilities to concentrate on the science rather than the measurement techniques.
In Sunalytic's string-level analytical monitoring of a similar to 10-20 MWp ground-mounted fixed-tilt crystalline silicon solar photovoltaics (PV) power plants in Southeast Asia, PV string losses due to bypass diode short circuit (BDSC) in PV modules were recorded on a regular basis, and verified by drone thermal images. Two types of SCADA data signatures that appear to precede BDSC failures are presented: both (1) rapid generation fluctuations, and (2) relatively stable generation. These observations are taken from single-BDSC-affected PV strings, a PV string affected by >1 BDSC, and also BDSC-affected PV strings located in the same section. Bypass diodes more robust to operational cyclic and heat stresses may be needed to mitigate this problem in solar farms. It is also clearly shown that effective analytics can detect such losses well ahead of scheduled drone thermal scans, helping asset owners to avoid unnecessary downtime and fetch higher financial returns.
Despite significant advances in wide band gap perovskite solar cells over the past several years, non-radiative recombination at the perovskite-electron transport interface continues to be a critical obstacle limiting device performance. This study presents a solution utilizing a thin interlayer of blended fullerenes [6], [6]-phenyl C61 butyric acid methyl ester (PCBM) and indene-C60 bis-adduct (ICBA) between the 1.77 eV perovskite and evaporated C60. Optimizing the blend to a trace 2% by mass PCBM in ICBA results in a hybrid electron transport layer (ETL) with improved energetic alignment, stronger molecular ordering, an order of magnitude higher electron mobility compared to neat PCBM or ICBA. When combined with surface passivation, this approach resulted in devices with 19.5% steady state efficiency, a fill factor of 0.85 and open-circuit voltage (VOC) of 1.33 V, which is within 10% of the radiative limit of VOC for this bandgap. Here we highlight the complex nonlinear behavior with fullerene mixing, and how controlling the energetics and crystallinity as well as the electronic properties of these materials is vital in mitigating nonradiative recombination and achieving high performing wide band gap perovskite solar cells.
This study examines the impact of soiling on the performance of photovoltaic (PV) systems at two sites in North Carolina, USA: Boone and Mount Holly. Custom-designed soiling monitoring stations, developed by the Photovoltaic Reliability Lab at Arizona State University, were installed at both locations to record short-circuit current and precipitation data. These measurements were used to calculate the Soiling Loss Factor (SLF), which quantifies the reduction in expected PV output due to soiling accumulation. Results indicate that, even during the driest observed periods, worst-case soiling losses did not exceed 6% and 3% at the Boone and Mount Holly sites, respectively. These findings offer practical guidance for developing cost-effective cleaning strategies, if any.
Doping of CdTe photovoltaics (PV) is essential to fabricate a high efficiency device. Traditionally, CdTe PV is doped with Cu, however, Cu doping cannot enhance hole density greater than 10(14) cm(-3) order. The excess Cu in the devices creates interstitial defects and limits the open-circuit voltage (V-OC) of the device. Alternatively, CdTe solar cells are doped with group V elements such as arsenic (As), phosphorus (P), antimony (Sb) and bismuth (Bi). The idea is to enhance the hole carrier density, and increase the quasi-fermi level splitting, and thus improve the V-OC of the device. This is usually carried out in-situ and ex-situ doping process. The In-situ group-V doping process brings its own challenges for the activation of group V dopants. Here, we discuss the activation of a group V (As) doped CdSe/CdTe photovoltaic devices. Our initial results indicate that the carrier density increased up to 3x10(15) cm(-3) with an activation ratio of similar to 1%, and device efficiency close to 16% for thermally evaporated CdTe devices.
Schottky barriers within PV devices have been a strong topic of interest for many decades. Modification of Schottky barriers can potentially mitigate the limitations in charge transport found in various PV technologies including cadmium telluride-based thin film PV. This study explores from a first-principles viewpoint how intermediate layers such as tellurium dioxide between a cadmium telluride absorber and gold metal electrode layer affect interfacial properties such as Schottky barrier height. Electronic properties inherent to the band alignment are calculated and compared between the CdTe/Au back interface without and with a tellurium dioxide intermediate layer.
This paper employs a multiphysics approach to introduce an opto-thermal-electrical model for plasmonic Schottky solar cells (PSSCs). It examines the optical properties, power conversion efficiency, and energy output of PSSCs, focusing on different geometries and sizes of nanoparticles (NPs). The spectral analysis considers absorption characteristics for NP radii from 10 nm to 150 nm in 3x3, 5x5, and 7x7 configurations. The study presents a novel energy yield model for PSSCs enhanced with Au-NPs on silicon absorbers, combining thermal, optical, and electrical responses to predict global energy yield maps. The total spectral heat absorption was measured across 300 nm to 1200 nm, with detailed analysis of NP heating and thermalization within the silicon absorber. Results show a significant improvement in electrical performance with the 5x5 NP array featuring a radius of 70 nm, yielding a short-circuit current density (Jsc) of 11.54 mA/cm(2), a 47% increase compared to traditional 2 mu m thick bare silicon Schottky cells. This improvement is associated with a notable rise in heat production within the NPs, with thermal gains soaring by 182.5% compared to uncoated silicon cells. To optimize performance and manage heat, advanced thermal management strategies are essential, with potential energy yield increases of up to 80 kWh/m(2) annually in sunny regions.
This study investigates the sensitivity of capacitance-voltage (CV) and drive-level capacitance profiling (DLCP) techniques to bulk and interface defect states in heterojunction solar cells using self-consistent numerical device simulations. In the presence of bulk and interface states, CV measurements on thin film solar cells often lead to misinterpretations of doping profiles. DLCP uses information from multiple AC test signal amplitudes and is nominally insensitive to interface states. CV, DLCP, and related techniques like admittance spectroscopy (AS) should all have different sensitivities to interface and bulk defects depending on the AC signal frequency, temperature, spatial and energetic distributions, and carrier capture and emission rates. Herein we utilize self-consistent numerical device physics simulations to characterize these sensitivities in a representative copper indium gallium diselenide (CIGS) thin film heterojunction solar cell. We investigate the sensitivity of CV and DLCP techniques under various scenarios of interface and bulk defects including changes in the density and spatial extent of near-interface states into the CIGS layer.
Photovoltaic cells are generally optimised for operation at 25 °C under the AM1.5 solar spectrum. This is useful for comparing different technologies, but ultimately energy yield (the energy output across a year of operation) is what we aim to maximise. This is generally estimated using the power conversion efficiency (PCE) of a cell at 25 °C and its temperature coefficient (how PCE changes with temperature). For monolithic tandem cells, this method is less accurate as current matching between each sub cell is required for maximum performance. To understand how to optimise tandems for energy yield, we fabricated perovskite/Si (30.8% PCE) and all-perovskite (25.4% PCE) tandems and tested them over a range of temperatures. Opposing temperature dependence with bandgap - perovskite bandgaps tend to widen with increasing temperature, whereas Si narrows - results in a worse temperature coefficient for perovskite/Si (-0.23%/°C) compared to all-perovskite tandems (-0.17%/°C). Increasing the Cs concentration at the perovskite A-site reduces the bandgap widening effect, resulting in an improved temperature coefficient (-0.19%/°C). Surprisingly, when estimating energy yields using real-world data, this improved temperature coefficient does not translate to increased yields. Instead, we find that the opposing temperature/bandgap correlation of perovskite/Si tandems is an advantage as the solar spectrum is blue-shifted compared to AM1.5 when cells are warmest and operate at their peak power output. Thus, we expect an increase in energy yield of up to 3% for optimised perovskite/Si tandems compared to other tandem technologies with the same PCE. Significantly, this equates to a full PCE point increase under standard conditions for optimised (> 30%) perovskite/Si tandems.
This paper presents a 7-year longitudinal study on a batch of photovoltaic (PV) modules. It introduces a combined indoor-outdoor approach for predicting their performance. This method not only effectively reduces measurement uncertainties but also improves the fit between the data and linear degradation models. In addition, this paper proposes a correction method to enhance the accuracy of outdoor testing. The study offers a novel perspective for the lifespan prediction of photovoltaic modules.
This work deals with the design and implementation of a battery charger/discharger controller based on the Sepic/Zeta topology oriented to the management of energy excess or deficits in a DC microgrid. The system must guarantee the DC bus voltage regulation during battery charging and discharging conditions and to operate correctly under different ratios between bus and battery voltages. To meet these requirements, a Linear-Quadratic-Integral (LQI) control strategy complemented with a Moving Horizon Estimation (MHE) is proposed. The control objective is formulated as an optimal control problem solved using LQR control theory, to which an integrator is added to eliminate the steady-state error. Incorporating MHE allows for an accurate estimate of the states, enhancing the controller performance and robustness to disturbances. In addition, a Feed-Forward control is integrated to increase the dynamic performance against sudden variations in the bus current. The LQI-MHE combination demonstrates efficient energy management under typical dynamic conditions of a DC microgrid, ensuring consistent system performance in the face of fluctuations in both charging and discharging operation. Finally, the results validate the effectiveness of the proposed approach, highlighting its potential in real applications with battery energy storage systems integrated in DC microgrids.
With the aim of meeting the needs of both the energy transition and the circular economy, it is imperative to develop photovoltaic panels with removable solar cells that can be reconditioned. We present a configuration of such a panel with three variants of charges collections on the front face. These three variants were fabricated and assembled in an inert environment (N2 glovebox). Their PV performances before and after a test degradation were analyzed. Anticipating an issue concerning ageing, H20 and O2 sensors were integrated into the prototypes to assess ant interpret the evolution of PV performances in a climatic chamber. The results, both in terms of tightness and PV performance degradation, are satisfactory, especially for one of the variants. Several improvements are proposed.
Chemical characterization of the thin passivation layers on commercial silicon photovoltaic (PV) cells is essential to understand and improve device performance and reliability. However, characterization methods are complicated by surface texture, which can cause shadowing and artefacts. Secondary ion mass spectrometry (SIMS) is an important tool for depth profiling silicon passivation layers due to its high chemical sensitivity enabling detection of hydrogen. Hydrogen concentration and migration is an important topic for reliability of silicon PV, especially for newer cell types such as the silicon heterojunction (SHJ) modules studied here. In these studies, we demonstrate the orientation of pyramidal surface texture with respect to the SIMS ion beam, and we give examples of different SIMS profiles on the same sample that depend on the angles (q) between the ion beam and (111) pyramidal face as well as (a) between the ion beam and the (100) direction normal to the sample surface.
Currently, polarization-type potential induced degradation (PID-p) is still a challenge for p-type PERC bifacial solar cells due to the polarization effect which causes an accumulation of charges in the passivation layer on the rear side of the cells. These accumulated charges decrease short circuit current (Isc), open circuit voltage (Voc), and power (P-max) in certain p-PERC modules. In this study, we investigated the behavior and progression of PID-p, with intermittent dark storage intervals, by applying high voltage on the rear side of the bifacial silicon solar cell for a long period. Tests were conducted under -1000V bias voltage, 35 degrees C for 10h. A total of 10 tests (100h) were conducted with intermittent 2-4 days of dark storage intervals, and PL images were taken before/after each test to observe degradation. We closely monitored Isc and observed a slight increase in Isc during the 1(st) stress for 10s, then a total of 5% degradation happened for 30h. Then, the cell showed a recovery to 99% of the initial value. After that, the I-sc started to decrease again. Notably, more degradation was observed after the dark storage, with a highest of 16.5% degradation which was recoverable with bias voltage. Collaborations at Arizona State University (ASU) and University of Central Florida also conducted PID experiments on custom minimodules fabricated using identical solar cells but different front and rear encapsulants under indoor (-1500V on the rear, 45 degrees C, 168h) and outdoor field conditions (-1500V for a couple of months), respectively, followed by dark storage afterwards. However, only the ASU minimodules exhibited degradation during stress and further degradation after dark storage. The key finding of our study is that while PID-p generally causes degradation in bifacial cells, additional degradation can also occur during dark storage, and it should be considered when characterizing commercial bifacial p-PERC modules.
This document presents an energy management system (EMS) that implements a game theory approach, using Nash equilibrium as a solution method to minimize operating costs and enhance prosumer revenue within a microgrid cluster (MGC). Prosumer revenue is determined by reducing energy costs, which depend on grid energy absorption and battery usage, considering the depth of discharge and battery type. The proposed approach is applied to a cluster of two PV-based microgrids within a neighborhood in a Puerto Rican town, where each microgrid features unique load and generation profiles as well as different battery sizes.The model operates over a seven-day window with a one-hour time step and is structured into stages, which are solved using Python.
We report on the enhanced performance of p-type silicon nanocrystals/silicon oxide composite layers, highlighting their potential as an effective solution for achieving high passivation and improved carrier conductivity. Notably, we observed a significant increase in carrier selectivity by the deposition of an AlOx:H film and the subsequent forming gas annealing. Through resonant nuclear reaction analysis, we revealed that hydrogen is effectively introduced into the composite layer in samples with enhanced carrier selectivity. These results suggest the crucial role of hydrogen in terminating defects within the composite layer, contributing to its overall high performance.
The fourth edition of the handbook serves as an all-encompassing resource for solar energy professionals, academia, and other stakeholders. The handbook is produced as a collaborative effort of 51 experts from 15 countries and contains the combined knowledge and experience of these foremost leaders in the field. This updated edition provides best practices for measuring, modeling, forecasting, analyzing, and utilizing solar resource data across various applications in solar energy. As the field of solar energy rapidly advances, so too does the understanding of solar resources. The fourth edition has undergone significant revisions, as evidenced by substantial updates across all existing chapters and the addition of two new chapters, bringing the total to 12 chapters. Recognizing that solar resources are fundamental to solar energy applications, this edition aims to furnish users with vital information that can lower costs and expedite solar deployment. This paper will introduce the audience to the fourth edition and highlight key new information that is crucial for users.
