TIB Open Publishing
Not a member yet
1994 research outputs found
Sort by
Reduction of Scarce Materials in Silicon Heterojunction Solar Cells and Implications on the Performance in the Field
Full text linkIn the first part of this work the potential to save silver for n-type silicon heterojunction solar cells was investigated. Cells were produced with varied frontside screen opening (30-50 µm). The groups were compared for efficiency at different irradiation levels and frontside silver laydown. For five busbar configuration large opening with low series resistance led to the highest efficiency for high irradiation around 1000 W/m² while for low irradiations all cells performed similarly. For busbarless cells lower silver laydown led to similar efficiency with slight advances for narrow screen opening. In summary cell technologies with small busbar-pitch are more tolerant for low-silver metallization. In the second part the impact of the transparent conductive oxide (TCO) was addressed. Silicon Heterojunction cells were produced with either ITO (indium tin oxide) only or an ITO-AZO-ITO (aluminium doped zinc oxide) stack, enabling an ITO reduction of about 50%, leading to a tolerable efficiency-drop of 0.3%. These internal samples were compared to industrial heterojunction-precursors (post ITO) with reference and low silver consumption frontside metallization. For both parts IV measurement showed that series resistance has a strong impact on efficiency but a rather small impact on low light-efficiency. Considering low light conditions TCO-precursor type with differences in passivation have a strong impact. On module level similar irradiation dependence of the efficiency was found and in temperature-dependent IV-measurements a positive impact of high-quality passivation on the temperature coefficients was found while an increase of the series resistance had a negative impact on the temperature dependence
Recycling of Photovoltaic Modules – A Strategy for Silicon and Metal Contact Recovery
Full text linkAs the installed capacity of photovoltaic (PV) systems continues to grow, also does the necessity to address the accumulating waste from decommissioned PV modules. Millions of modules will need to be retired in the next few decades, and this poses a challenge that requires the development of cost-effective and efficient recycling strategies, with a focus on essential components such as solar cells, which are known for their significant environmental impact and energy budget. This study explores strategies to recover metal from front and rear contacts, as well as the potentiality of silicon substrate recrystallization. Alkaline-organic solutions allow for complete metal detachment with small-to-minimal silicon loss, and recrystallization of recovered substrates provides promising results in obtaining wafers suitable for the newly established industry requirements. Al-BSF solar cells fabricated from recycled materials exhibit improved performance, proving the feasibility of reclaiming precious metals and silicon substrates from PV modules. These encouraging first results represent an important step towards cycling PV systems within a circular economy framework, thereby minimizing waste and maximizing resource utilization
Evaluation of Cells Cracks Impact on PV Module’s Performance
Full text linkThis work aims to perform an assessment of cell cracks impact on PV module’s performances. Cracks can occur during transportation, severe weather conditions such as hailstorms [1], poor installation practices and manufacturing [2]. Even with multiwire interconnection technologies, the impact of such defects can affect PV module’s performances as well as the energy yield and lifetime of a photovoltaic installation [3]. Moreover, cracks will leave the silicon edge unpassivated with a risk of being more sensitive to external stresses, especially on highly efficient technologies like TOPCon. The main objective of this work is studying the cracks impact on new module’s technology performance to quantify its impact on the production yield and forecast power plant performance. A laboratory testing sequence was performed on two different Glass/backsheet PV technologies: PERC and TOPCon. First, a cracking procedure was conducted to generate several cracks patterns on two batches of PV modules similar to the patterns observed on powerplants sites. An electrical characterization was then performed to carry out a first evaluation of power losses after the cracks. Moreover, several accelerated aging sequences were conducted on the cracked and reference modules to quantify the average losses after each accelerated aging test
The Stability of the Global Wheat Trade in the Post-Soviet Space: A Trade Duration Approach
Full text linkThe collapse of the Soviet Union and the Iron Wall as well as the emergence of Kazakhstan, Russia, Ukraine and Romania as major actors on international grain markets since 2000 had increased the hope for a more stable international grain market. However, various short-run trade policy interventions of post-Soviet grain exporting countries during the 2000s and 2010s have caused temporary disruptions in global grain supply chains. Moreover, the growing number of protectionist state interventions and sanctions since the beginning of the 2010s, as well as growing geopolitical tensions, may also fragment global trade and thus threaten the stability of grain trade relations. Against this backdrop and given the current public and political debates about suitable “de-risking strategies” to stabilise international trade, this article aims to explore the stability of the global wheat trade in terms of the duration dependence of trade relations between the major grain exporters and their destinations from 2001 to 2021. We test whether there are differences between the relatively “new” post-Soviet exporters that have emerged and the “old” ones. Furthermore, we examine the correlation between the number of trade partners and the trade duration. We employ a discrete-time hazard model to annual trade data to estimate the baseline hazard and survival rate for eleven major wheat exporting countries. The results indicate that, by having overall duration dependence, no different pattern in trade stability can be identified between “new” and “old” actors, and initial indications suggest that having more trading partners favours the survival of trade relations
Heat Transfer and Pressure Drop in Packed Beds of Crushed Rock Particles
Full text linkThermal energy storage using packed beds of crushed rocks finds application in solar thermal power generation, building thermal comfort, and greenhouse climate control. Crushed rock particles are irregular in shape and size, but notwithstanding have a clearly discerning long, intermediate, and short axis. Consequently, particles tend to pack down with their short axis facing upwards. As a result, the flow resistance and heat transfer characteristics in a packed bed depend on the flow direction relative to particle orientation. For small applications, the flow through a packed bed is typically one-dimensional, and one may rely on empirical correlations for design purposes. In this work, we propose that tortuosity is included in the heat transfer and pressure drop correlations. We derived our correlations from a combination of discrete element modeling (DEM) and computational fluid dynamics (CFD) and verified our results experimentally
Wirtschaftszahlen (Stand: 15.05.2025)
Full text linkWirtschaftszahlen: This database contains general data on the development of agricultural producer and input prices, the consumer price index and foreign trade in agricultural and food goods on a monthly basis for the previous 24 months. In addition, this database comprises important volume and price developments on national and international markets for selected product groups of agricultural products such as grain, livestock, meat, milk and dairy products as well as vegetables, fruit and sugar. This file is only available in German
Implementation of PIDs and Plans for FDOs in the RSpace Digital Research Platform
Full text linkIn this contribution we describe our plans to use FDOs in the RSpace research platform and express our interest to include RSpace into the FDO testbed
Meet the FDO Manager: Reference Implementation of FDO Operations (Create, Retrieve, Update, Delete) Based on the Digital Object Interface Protocol (DOIP).
Full text linkThe FDO Manager is a free and open source reference implementation of basic FDO Operations like retrieve, create or update. It is based on the Digital Object Architecture and realizes an FDO architecture employing persistent identifiers that can be resolved via the Digital Object Identifier Resolution Protocol
Modeling the Agrivoltaic Potential for Land-Intensive Commodity Crops
Full text linkCorn and soybean farming use about two-thirds of the agricultural land in the US. To accelerate the large-scale adoption of agrivoltaics, best practices that are compatible with traditional farming operations for corn and soybeans need to be developed. In this presentation, we present the development of a modeling framework to explore the benefits and trade-offs between crop growth and photovoltaic (PV) electricity generation for common commodity crops at the county level. Our model couples a crop growth model, a soil water balance model, and a PV model in one integrated scheme. As an example, we consider corn growth in Renville County, MN. The model suggests that there is a ~0.55% loss in crop yield upon 1% shading because the crop-diminishing effect of reduced radiation is partially offset by increased water retention in the ground
German Renewable Energy Policies and Their Implications for Local Land Use – Maize for Biogas From 2008 - 2018 in Brandenburg
Full text linkThis study investigates the spatiotemporal dynamics of maize cultivation for biogas production in Brandenburg, Germany, from 2008 to 2018, employing a spatially explicit multicriteria analysis. By combining plot-level land-use data from the Integrated Administration and Control System (IACS) with biogas pnt information, we analyze the likelihood of maize cultivation for biogas at the plot level and find that maize for biogas accounts for over 5% of the total arable land in Brandenburg. We identify patterns of high concentration, particularly in the northwest of the region. The analysis also reveals a steady increase in maize cultivation, aligning with regulatory changes in the Renewable Energy Sources Act (EEG). These findings offer valuable insights into the spatial patterns and drivers of biogas maize production, providing a basis for future environmental and economic research. The study highlights the need for plot-level information to evaluate the effects of renewable energy policies on local land use