Gaby J.M. Janssen

THE INFLUENCE OF CARBON DIOXIDE ON PEM FUEL CELL ANODES

The influence of CO2 on the performance of PEM fuel cells was investigated by means of fuel cell experiments and cyclic voltammetry. Depending on the composition and microstructure of the fuel cell anode, the effect varies from small to significant. Adsorbed hydrogen plays a dominant role in the formation of CO-like species via the reverse water–gas shift reaction. Platinum sites which are not utilized in the electrochemical oxidation of hydrogen are thought to catalyze this reverse-shift reaction. Alloying with ruthenium suppresses the reverse-shift reaction.

Input Parameters for the Simulation of Silicon Solar Cells in 2014

Within the silicon photovoltaics (PV) community, there are many approaches, tools, and input parameters for simulating solar cells, making it difficult for newcomers to establish a complete and representative starting point and imposing high requirements on experts to tediously state all assumptions and inputs for replication. In this review, we address these problems by providing complete and representative input parameter sets to simulate six major types of crystalline silicon solar cells. Where possible, the inputs are justified and up-to-date for the respective cell types, and they produce representative measurable cell characteristics. Details of the modeling approaches that can replicate the simulations are presented as well. The input parameters listed here provide a sensible and consistent reference point for researchers on which to base their refinements and extensions.

Chapter Five - Materials for State-of-the-Art PEM Fuel Cells, and Their Suitability for Operation Above 100°C

Abstract This review gives an overview of proton exchange membrane (PEM) fuel cells on the materials level. Materials for proton conducting mesmbranes, electrodes and bipolar plates are described from the perspective of their suitability for long-term operation in automotive and stationary applications. The state-of-the-art PEM fuel cells consisting of perfluorosulfonic acid membranes, platinum-based electrodes and graphite(-composite)-based bipolar plates are in a well advanced state of development. Although the main constituents are in use for many years, impressive improvements in performance and lifetime have been realized, leading to cost reduction, size reduction, improved robustness and mass manufacturing. For the sake of system simplification, increasing the temperature of operation of the proton exchange membrane fuel cells (PEMFC) would be beneficial. New materials are needed to enable operation at higher tem- peratures, and not less important, lower relative humidities. The suitability of present state-of-the-art materials for operation above 100°C is discussed, as well as a critical review of the suitability of emerging concepts. No alternative material that combines the virtues of the present materials with the ability of operation above 100°C has been developed so far. Therefore, the first commercial introduction of PEM fuel cells is likely to be based on the components that are at present in use, making use of perfluorosulfonic acid membranes.

20.3% MWT Silicon Heterojunction Solar Cell—A Novel Heterojunction Integrated Concept Embedding Low Ag Consumption and High Module Efficiency

In this paper, we present the successful integration of a silicon heterojunction (HJ) solar cell with metal wrap through (MWT) architecture. This MWT-HJ cell and module technology combines all the advantages of the individual concepts. With this contribution, we demonstrate a record device efficiency of 20.3% achieved using commercial n-type Cz 6-in wafers. To our knowledge, this is the first time cell results for MWT-HJ architecture have been reported. We put this result in perspective, providing a solution for the reduced conductivity of low-temperature silver pastes used for HJ cell fabrication. We propose a method to further increase the solar cell performance up to 4%rel, together with a 50% cost of ownership reduction of the front contact silver, including via and conductive adhesive at the rear. This is possible solely by the optimization of the front metal grid in this MWT structure predicting efficiencies above 21%. MWT-HJ is a fully low-temperature integrated cell and module concept and is also compatible with next-generation thinner wafers.

PEM Fuel Cell Materials: Costs, Performance and Durability

The Proton Exchange Membrane Fuel Cell, PEMFC or PEFC, is in development for transport applications as well as for power generators ranging from a few Watts to tens of kilo Watts. Despite the fact that fuel cells have many advantages, such as a high conversion efficiency at partial load, clean exhaust gases, modular design and low noise production, their marketability will depend heavily on whether these fuel cells can compete with the incumbent technologies on performance, cost, and reliability in a specific application. For transport, the benchmark at present is the internal combustion engine, which has been mass-produced since 1908, and is characterized by high performance, high reliability, and relatively low cost.

Crystalline silicon interconnected strips (XIS): Introduction to a new, integrated device and module concept

A new device concept for high efficiency, low cost, wafer based silicon solar cells is introduced. To significantly lower the costs of Si photovoltaics, high efficiencies and large reductions of metals and silicon costs are required. To enable this, the device architecture was adapted into low current devices by applying thin silicon strips, to which a special high efficiency back-contact heterojunction cell design was applied. Standard industrial production processes can be used for our fully integrated cell and module design, with a cost reduction potential below 0.5 €/Wp. First devices have been realized demonstrating the principle of a series connected back contact hybrid silicon heterojunction module concept.

Electrode Degradation in PEMFCs as Studied in Model Systems and PEMFC Testing

University of Technology Eindhoven, PO Box 513, 5600 MB Eindhoven In order to meet the durability criteria for PEM Fuel Cells, needed for their successful application in transport, more insight is needed into which conditions have a detrimental effect on the long term performance, and which materials improvements are needed to make PEMFC better suited to withstand some of these conditions that are unavoidable in practice. To obtain such insights

Metal Wrap through Silicon Heterojunction Solar Cells and First Made Minimodules

In this paper we present the successful integration of a silicon heterojunction (HJ) solar cell with metal wrap through architecture (MWT) and foil basedback contact module technology. With this contribution we show a record cell efficiency of 20.3% achieved using commercial n-type Cz 6 inch wafers and demonstrate an encapsulated cell efficiency of 19.6% achieved on a 2×2 mini-module. To our knowledge this is the first time that module results of MWT-HJ architecture have been reported. In this studies , we propose a method to increase the solar cell performance up to 21% together with a 50% cost of ownership reduction of the front silver metal including via and conductive adhesive. This is possible solely by the optimization of the front metal grid. MWT-HJ is a fully low-temperature integrated cell and module concept compatible also with thinner wafers.

XIS: A low-current, high-voltage back-junction back-contact photovoltaic device

In this paper we present a low-current, highvoltage back-junction back-contact integrated photovoltaic concept and experimental results of such a device, consisting of strip cells: narrow solar cells instead of conventional square cells. The concept is demonstrated by the successful transformation of a completely finished IBC cell into a XIS (Crystalline Silicon Interconnected Strips) device, leading to a Voc of 8.5 V for a series connection of 14 strip cells. For cell separation, different grooving methods were evaluated with respect to their effect on the quality of the groove surface. The effect of the surface passivation in the grooves, which is regarded as a critical parameter, on the XIS device was simulated to gain a better understanding of the processing requirements.

23% Efficiency metal wrap through silicon heterojunction solar cells

MWT-SHJ cells and modules combine the positive benefits of both underlying technologies: namely high Voc, higher Jsc and higher FF. Especially the FF is maintained before and after encapsulation thanks to the rear interconnection which strongly reduces cell to module FF losses. We obtained two record efficiencies for these devices with two different front metallizations: 22.6% using low temperature Ag paste and 23.1% using copper plating. Voc values above 730 mV have been achieved also in the new 6×6 vias metallization, demonstrating that the architecture maintains the exceptional passivation typical of heterojunction devices. The MWT cell and module structure offers even greater advantages on heterojunction solar cells: i) front side Ag consumption reduction up to a factor two; ii) concurrent low temperature cell interconnection and encapsulation. Our record MWT-SHJ solar cells and modules are manufactured using industrially proven tools and 6 inch commercial n-type Cz Si wafers. The metallization choice gives ample room to manufacturers for optimization based on internal cost structure, material costs and business strategy. MWT-SHJ behavior at reverse bias voltage and low illumination intensity is comparable to conventional HJ devices.