Based on simulation and outdoor measurement results the bifaciality effects are quantified for a bifacial perovskite on silicon tandem device.

Nowadays, the solar cells for space applications, designed to provide highest performance values at end of life (EOL) conditions under a constant Sun spectrum, are used without modification also for missions on Mars surface where the spectral conditions differs significantly from the typical space missions ones. As part of the solar cell optimization process, the comparison of the existing AZUR 3G30 and AZUR 4G32adv solar cells performance under various Martian conditions together with the analysis of possible improvements highlights that the AZUR 4G32 cell has a better potential than AZUR 3G30. The optimized AZUR 4G32 developed for Mars conditions and presented in this paper shows an increase of around 5% with respect to the current 4G32adv and 13% with respect to 3G30 cell under the selected reference conditions. Even higher performance boosts are presented under other Martian conditions. Characterization (Spectral Response and Dark I-V) performed on the optimized AZUR 4G32 structure in the temperature range -150 degrees C + + 50 degrees C allows to extract the parameters needed for a 2-diode model. The validation of the extracted parameters shows low deviation between measured and calculated dark IV curves. Comparisons of measured and calculated light IV curves for the five Martian scenarios show good agreement confirming that the model allows for the calculation of the solar cell performance under any illumination and temperature conditions on the Martian surface.

In micro-concentrator photovoltaics (micro-CPV) minimized components as cells (<1 x 1 mm(2)) and lenses are used, promising significant cost reductions through parallel manufacturing and reduced material volumes. However, tolerances, such as deviations from nominal size, geometry or position, impact module performance, especially for non-ideal alignment towards the sun. To study the interplay of different, independent tolerances and their effects on current generation, a comprehensive parameter study is practically not feasible, because of the vast number of possible combinations. In this work, we introduce a novel method for assessing tolerances by employing a Monte-Carlo approach to randomly select and combine tolerances in a cell-lens unit. It allows to identify relevant tolerances and quantitatively assess their influence on module performance, namely optical efficiency, and photocurrent as function of angle of incidence and, thus, acceptance angle. We apply the model to a micro-CPV module developed at Fraunhofer ISE and use tolerance distributions based on measurements. We find that the most crucial parameter is the position of the secondary optical element. Given the measured tolerance distributions, the acceptance angles for 90 % of the cases are above 0.5 degrees for 10 % current loss. The developed approach is a crucial tool for identifying and assessing critical tolerances within a manufacturing line, facilitating techno-economic optimization of design and manufacturing processes.

In manufacturing and product optimization, understanding the influence of tolerances, which are inevitable variations in production processes, is crucial for enhancing performance while managing costs. However, previous analytical approaches lacked the capability to quantitatively assess the cumulative effect of multiple tolerances due to their random combination and statistical independence. In this work, we introduce a novel method that overcomes these limitations by effectively modeling complex dependencies among tolerances through a two-step nested Monte-Carlo approach. We apply this model to a micro-CPV module developed at Fraunhofer ISE. First, we randomly select and combine tolerances in a cell-lens unit using ray tracing. Then, we randomly select and combine these units in a full 690-cell module using an electrical network model considering different angles of incidence. The considered tolerances include deviations in component geometries and displacements and are based on measurements. The model predicts the acceptance angle and allows to identify the optimal interconnection schemes. Further, it is capable to determine the maximum tolerances permissible for maintaining a certain module power. While tolerances lead to a distribution in current generation among the cell-lens units, we find that parallel interconnections can compensate for such variations. Further, we identify that the positions of secondary lens and micro solar cell are the most sensitive parameters for achieving high module power. These findings are crucial for refining module design cost-effectively. Moreover, the model facilitates a quantitative assessment of optimization potentials, guiding decision-making in product development and manufacturing, and a techno-economic optimization.

Micro-concentrating photovoltaic (micro-CPV) technology has the potential to contribute to the energy transition, facilitating the shift toward more sustainable and renewable energy sources by combining minimal carbon footprint and energy demand with low levelized cost of electricity. Micro-CPV modules utilize direct normal irradiance to convert sunlight into electrical power, necessitating precise solar tracking. The performance of these modules is influenced by their alignment toward the sun and prevailing outdoor conditions during outdoor operation. The spectral conditions, along with the ambient temperature, irradiance, and wind speed, influence the current-voltage characteristics of multijunction solar cells and the optical behavior of the lens. We have developed a novel micro-CPV module concept, which is based on low-cost and high-throughput manufacturing processes. In this work, we present a prototype module in a 10 x 6 array configuration (205-cm(2) aperture area, submodule class). We discuss outdoor measurements recorded over one year and the influences of various outdoor conditions. In an IEC62670-3 power rating, efficiencies of 36.0 +/- 0.4% and 33.0 +/- 0.4% at concentrator standard test conditions and concentrator standard operating conditions, respectively, are determined. Highest efficiencies, about 0.4% higher than at standard conditions, were attained at a more red-rich spectrum, namely at a spectral matching ratio SMR12 of 0.94 +/- 0.03. Using measurements at different temperatures, we show that the planoconvex silicone-on-glass primary lens has a negligible temperature dependence. Changes in the module performance over the course of one year are discussed. Despite employing commercially available low-cost components and high-throughput processes, no significant degradation was observed during the first year of operation.

Spectrometric characterization allows for accurate determination of the current matching point and investigation of sub‐cell properties of multi‐junction solar cells. It is widely used for dual‐junction solar cells. Although the concept is suggested for triple‐junction solar cells, it is only applied for the variation of two sub‐cells. In this work, the applicability and evaluation procedure for a systematic variation of all three sub‐cells of a triple‐junction solar cell are presented. Clearly defined measurement conditions are derived which allow for meaningful characterization and comparisons of different triple‐junction devices. The presented procedure is exemplarily tested on a III–V on silicon triple‐junction solar cell using an light‐emitting diode‐based solar simulator where all needed spectral conditions can be calculated in advance and accordingly adjusted. Spectral conditions around the air mass 1.5 global spectrum are chosen and a fit routine to determine the current matching point from the discrete measurement points is proposed and validated by a measurement with a higher resolution around the current matching point. Finally, it is shown that the spectral conditions applied during the measurement also reflect outdoor conditions. This highlights the relevance of the presented procedure beyond the determination of the current‐matching conditions.

In micro concentrating photovoltaics (CPV) minimized components are used and promise significant cost reduction due to massive manufacturing parallelization. At Fraunhofer ISE, we have developed a micro-CPV module based on a circuit board on glass, 5-junction micro concentrator solar cells, spherical ball lenses and a silicone-on-glass primary lens optics. Various prototypes from single cell-lens units to panel-sized 24“×18” modules were fabricated and tested. Due to the small size of the components, process tolerances are of special relevance and can significantly affect module performance. We present a novel modeling approach to study this influence quantitatively based on a nested Monte Carlo optical and electrical simulation. Furthermore, we present experimental results of prototype modules measured outdoors. For a 60-cell submodule-class prototype a power rating according to IEC 62670–3 was performed and CSTC and CSOC efficiencies of 36.5% and 33.0% are demonstrated.

In recent years, significant progress has been made in terms of efficiency and stability of perovskite on silicon (Pero/Si) tandem solar cells. Nevertheless, most of these activities are focused on small‐area laboratory cells while the availability of large‐area solar cells suitable for module integration on an industrial level remains limited, and therefore, measurements of tandem modules are rare. However, the reliable measurement of tandem modules is a prerequisite to evaluate the real potential of this rapidly developing technology for the photovoltaic market. In this study, we present the first published outdoor measurement of a full‐size bifacial Pero/Si tandem solar cell module. Our focus is on analyzing the spectral influences on the outdoor performance of the device through a qualitative assessment of the modules I – V parameter conducted over the course of a measurement day. Based on continuous monitoring of the ambient and module conditions, we provide consistent explanations for the complex interplay between the incident irradiance on both the front and backside of the module, as well as the module temperature. Based on our findings, we finally discuss how to appropriately account for the influence of bifaciality in the case of bifacial tandem modules, where the procedures used for bifacial single‐junction devices cannot be easily applied due to subcell limitation effects. Throughout the study, we present important insights into the real‐world characteristics of a bifacial Pero/Si tandem model, discuss and explain various influences on the modules performance, and therefore provide crucial information for an optimal cell design for bifacial Pero/Si tandem devices.

Low-cost approaches for mass production of III–V-based photovoltaics are highly desired today. For the first time, this work presents industrially relevant mask and plate for front metallization of III–V-based solar cells replacing expensive photolithography. Metal contacts are fabricated by nickel (Ni) electroplating directly onto the solar cell’s front using a precisely structured mask. Inkjet printing offers low-cost and high-precision processing for application of an appropriate plating resist. It covers the solar cell’s front side with narrow openings for subsequent electroplating. The width of the resulting Ni contacts is as low as (10.5 ± 0.8) µm with sharp edges and homogenous shape. The 4 cm 2 -sized champion III–V-on-silicon triple-junction solar cell with mask and plate front metallization reaches a certified conversion efficiency η of (31.6 ± 1.1) % (AM1.5 g spectrum). It performs just as well as the reference sample with photolithography-structured evaporated front contacts, which reaches η = (31.4 ± 1.1) %.

The procedures for the power rating of tandem-cell-based concentrator photovoltaic (CPV) modules defined in the international standard IEC 62670-3 are adapted to the requirements of tandem-cell-based flat plate PV modules. The adjusted procedure describes how to translate outdoor measured PV current-voltage characteristics to standard test conditions (STC): 1000 W/m, 25 degrees C cell temperature, AM1.5g spectral conditions. In this work, we describe how to obtain all required input parameters: thermal transient measurements to determine the module temperature coefficients, categorizing and filtering the prevailing spectral irradiance conditions using spectral matching ratios, and determining the 25 degrees C module open-circuit voltage from dark current-voltage curves. Three specimen PV modules (triple-junction, III-V on Silicon and III-V on Germanium) have been measured for several months outdoors on a dual axis tracking unit at Fraunhofer ISE in Freiburg. In this work, we demonstrate that the CPV module power rating procedures in IEC 62670-3 are also-in a modified form-to be recommended for the outdoor rating of tandem-cell-based flat plate PV modules.

In this work, a method to calculate the aerosol content in the atmosphere and the prevailing spectral irradiance of the sunlight is introduced. This method does not aim for low measurement uncertainty but for cost effectiveness and does not require sophisticated equipment. The bases of the method are the clear sky direct normal irradiance (DNI) and a look‐up table calculated with the software tool SMARTS2. The ratio of clear sky DNI to the prevailing DNI in combination with the look‐up table allows the determination of aerosol optical depth (AOD), spectral matching ratios (SMR), and spectral irradiances. Besides the prevailing DNI, the following ambient condition parameters are required: Air pressure, relative humidity, and ambient temperature. This means a weather station and a pyrheliometer are sufficient for the determination of the prevailing spectral irradiance. Obviously, this method cannot guarantee the same accuracy as conventional spectral irradiance measurement methods (e.g., using a spectroradiometer). However, in this work, we demonstrate the potential of this new method as a fall‐back strategy for missing spectral irradiance data. This method is worth using when (C)PV module power output data needs to be evaluated in dependence of the composition of the spectral irradiance, but no regular spectral irradiance data are available. In this paper, the AOD and SMR values determined with the introduced method are compared to measurement data with common measurement devices demonstrating a satisfying agreement. The spectral irradiances calculated with this method are successfully tested for using as the basis for energy yield calculations and for the determination of the CPV module power output at Concentrator Standard Conditions according to IEC 62670‐1.

Energy yield calculations for CPV modules that use tandem solar cell technology have been performed and analysed in this work. Two BSQ D280 CPV modules were used as specimen: one located in Freiburg, Germany, and one in Greater Noida, India. The current–voltage curves of both modules were measured for several months together with the prevailing ambient conditions. The energy yield in the respective measurement periods were calculated using the software PVsyst. It has been found that the energy yield modelled with PVsyst has a good agreement with the one measured in Freiburg, but deviates by 10% from the one measured in Greater Noida. The reason is most likely the high aerosol content in Greater Noida and thus the non‐appropriate consideration of spectral irradiance impact by PVsyst, which uses air mass and DNI as the only atmospherical parameters. The accuracy of the PVsyst calculation has been strongly improved in this work by using SMR corrected DNI values as input for the PVsyst calculation. In this manner, the impact of spectral irradiance variation on (C)PV module power output can be considered in energy yield calculations by PVsyst. The deviation of the calculated and measured energy yield could be reduced to below 1%.

Within the EU-funded project HIPERION, significant progress has been made on the Insolight solar panel: a high-efficiency rooftop compatible micro-CPV device with integrated planar microtracking and diffuse collection via additional low-cost Si solar cells. The IES-UPM and other R&D centers in the consortium have been tasked with characterizing the various generation of this technology. In this work we discuss the evolution of the module design and present the latest results for "Genl" solar panels showing significant improvement in performance in self-tracking compared to earlier results even in the face of a 5X increase in module area.

The IEC standard 62670-3 covering the power rating of CPV modules has been published in 2017. However, this rating procedure has already been applied for the first time at Fraunhofer ISE in Germany in the year 2014. Since then it has been used many times in Freiburg for several different CPV modules from various manufacturers. Amongst them are modules with different cell types (3J, 4J, 5J), various lens sizes (1x1 cm(2) to 15x15 cm(2)), and lens types (PMMA, full glass, silicone on glass). In this paper some of the experiences which have been gathered in these 7 years since 2014 on the power rating of CPV modules are going to be presented. The measurement uncertainty of the IEC 62670-3 rating approach has been calculated exemplarily to 7 Ara. In this work we will present the main contributors to this measurement uncertainty and we will discuss the deviations which have been found for the V-OC at 25 degrees C derived from dark vs light I-V curves. Furthermore, for several CPV modules of various technologies the nominal CSTC efficiency has been determined from indoor and outdoor light I-V measurements. The agreement between indoor and outdoor rating has been found with +/- 4 % in the worst case.

Several technologies have been identified that could produce a new type of high-performance solar product optimized for space-constrained applications: micro-CPV, planar microtracking, and diffuse capture. The Swiss start-up Insolight and the Hiperion consortium are bringing such a device to the industrial level. In this work we share the latest results for full-scale modules, discuss improvements to the design and resulting performance gains, and will report the results from pilot installations in Madrid and Freiburg.

With miniaturization of dimensions, new manufacturing methods e.g. from microelectronics may lead to cost reduction of CPV. In this work, we focus on the thermal, electrical and optical boundaries of the micro-CPV module technology with respect to cell and lens miniaturization. Open-circuit voltage losses due to recombination at the solar cell perimeter and dark area as well as high operating temperature are investigated. The smaller the cell the higher the losses due to increased perimeter-to-area ratio. On the other hand, lower optical power per cell leads to lower temperatures and thus increased voltage. Based on the electrical and thermal simulations, an optical configuration for a two-stage optics with piano-convex primary optics and a glass sphere as secondary optical element is presented. Besides optical efficiency, also acceptance angle and flux distribution are considered. Simplified simulations where only two wavelengths are considered compare well with detailed full spectrum simulations. We identify two regions of high optical efficiency. Detailed simulations showed that only in one of the regions, the flux distribution on the solar cell is acceptable. The results are the basis for a module configuration that will be realized as a prototype in future work.

With the 5C46 AZUR SPACE is introducing its new CPV cell into the market. This upright metamorphic AlInGaP/InGaP/AlInGaAs/InGaAs/Ge 5-junction cell uses sub-cell materials comparable to AZUR's 4G32 space solar cell but has an additional InGaP junction. The cell design is laid out for optimum module performance at operating conditions. As reported earlier, the bandgaps of the sub-cells have been selected to avoid the dips in the AM1.5d spectrum for cell temperatures up to 90 degrees C. The optimization of the 5C46 has been monitored by the manufacture of 5C46-based commercial CPV modules equipped with secondary lenses and rating of these modules at Fraunhofer ISE. A very good efficiency of 31.7% at Concentrator Standard Operating Conditions (CSOC, lens array aperture) has been reached corresponding to a power boost of 17.5% compared to reference modules equipped with 3C44 cells. In the last optimization step, the thicknesses of the sub-cells have been adjusted to achieve current matching under operating conditions on module level. The paper describes the method used for modelling and the calculation of the optimum thicknesses. It involves the determination of the absolute quantum efficiency of the bare cell and accounts for the thermal band-gap shifts as well as the optical effects due to mounting of the secondary and the transmission of the primary lens. First outdoor results of modules equipped with the final 5C46 design confirm that the current-matching for operating condition on module level was successfully achieved by the described method.

This article summarizes the IEC compliant power rating procedure applied to a hybrid CPV/PV module of the EyeCon technology which uses III-V four-junction CPV cells in combination with bifacial c-Si PV cells. The combined power output of both solar cell types at standard test conditions reached 342 W/m(2), which corresponds to a world record efficiency of 34.2% for the conversion of the reference AM1.5g spectrum. For the first time, we present the annual energy yield of the 4J EyeCon module for the six reference climate zones defined in the energy rating standard IEC 61853-4. When comparing the hybrid yield with the highest electrical generation between conventional CPV and flat-plate PV modules, we found that hybrid CPV/PV technology delivers a maximum energy surplus of 20% in temperate continental climate.

Hybridization of multi‑junction concentrator photovoltaics with single‑junction flat plate solar cells (CPV/PV) delivers the highest power output per module area of any PV technology. Conversion efficiencies up to 34.2% have been published under the AM1.5g spectrum at standard test conditions for the EyeCon module which combines Fresnel lenses and III-V four‑junction solar cells with bifacial c‑Si. We investigate here its energy yield and compare it to conventional CPV as well as flat plate PV. The advantage of the hybrid CPV/PV module is that it converts direct sunlight with the most advanced multi‑junction cell technology, while accessing diffuse, lens‑scattered and back side irradiance with a Si cell that also serves as the heat distributor for the concentrator cells. This article quantifies the additional energy yield per module area expected from hybrid CPV/PV modules and therefore gives clear guidance towards establishing competitive business cases for the technology.