In the presented paper, we introduce an approach to rate the performance of modules under specific real weather conditions, since solar modules are rated according to standard test conditions which ...do not give evidence of the performance under real outdoor conditions. Therefore, we categorize the daily weather at a photovoltaic test site into 7 different climatic‐day classifications and multiple cloud scenarios. Two different approaches to evaluate the cloud conditions were investigated. Furthermore, we use the developed approach to rate the performance of 8 different commercially available photovoltaic modules that have been installed and measured in Germany. The evaluation shows that module properties (eg, temperature coefficient, spectral response, and mechanical construction) have a major influence on the performance of photovoltaic modules under different weather conditions.
An approach to rate the performance of modules under specific real weather conditions is introduced, since solar modules are rated according to standard test conditions which do not give evidence of the performance under outdoor conditions. We use the developed approach to rate the performance of 8 different commercially available photovoltaic modules that have been installed and measured in Germany. The evaluation shows that module properties have a major influence on the performance of photovoltaic modules under different weather conditions.
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•An experimental CPC PVT solar collector was built, in order to examine the impact of CPC reflectors on the pv efficiency.•Ray tracing simulations showed the flux distribution of CPC ...reflectors for different incoming angles.•Eight different CPC geometries with three different concentrations were built and tested under in situ conditions.•A model combined ray tracing, thermal and electrical behavior and quantified the various effects of pv efficiency loss.
PVT collectors aim for the co-generation of pv electricity and heat. The following concept intents to raise the thermal efficiency by concentrating sunlight with CPC reflectors, in order to access a higher number of solar thermal applications.
The work presented here, focuses on the influence of the CPC reflectors on the pv efficiency. Parabolic concentrators in general, and CPC reflectors in particular, cause a non-uniform illumination of the pv cells, which decreases the pv efficiency. Ray tracing calculations of one particular CPC geometry result in a characteristic, angular dependent solar flux distribution in the cell plane.
The effect of this flux distribution was measured on a real scale experimental collector on a outdoor solar test stand. The incidence angle modifier (IAM) of the pv efficiency was measured for three different concentrations, as well as for an improved CPC geometry, aiming to homogenize the flux distribution in the cell plane.
The experiments showed, that the pv efficiency drops from 15% at STC to between 9% and 11%, depending on the solar concentration factor, which influences the efficiency negatively. The predicted efficiency boost of the improved CPC geometry could not be validated experimentally, as the additional optical losses of the more complex setup were high compared to its improvement effect.
In order to understand these results, a theoretical model was built, combining ray tracing, electrical and thermal modeling of the CPC PVT collector. This model enabled to calculate the temperature distribution, as well as the pv efficiency simultaneously, by dividing the pvt absorber into finite elements.
Temperature accelerated lifetime measurements are applied to conjugated polymer based bulk heterojunction solar cells. The short circuit current under white light illumination is monitored over time ...for different temperatures, ranging from 40 C to 105 C. An Arrhenius type dependence of the degradation constant with temperature is observed and an activation energy Ea of {/content/VYJD9RF1A2UD027G/xxlarge8764.gif}350 meV is derived.
An organic n‐type transistor, where both insulating and active layer were processed from solution, has been produced. As the active layer the C60‐derivative, 6,6‐phenyl C61‐butyric acid methyl ester ...(PCBM), was used. Its electron mobility was determined to be as high as μe = 4.5 × 10–3 cm2 V–1 s–1 when calcium drain/source contacts were used. If these contacts are formed from more air‐stable metals, the device performance decreases.
This contribution analyses the performance potential of state of the art organic bulk-heterojunction photovoltaic devices and gives a guideline towards higher device efficiencies. The concept relies ...on the identification and determination of the relevant material parameters (lifetime, mobility, bandgap, trap density….) for the pristine components and for the blended photovoltaic composites. These material parameters are used as the input for a simulation model, which is demonstrated to correctly describe bulk heterojunction solar cells. Results from simulation are compared to experimental device performance. Comparison between experiment and simulation allows to analyse deficiencies of the pristine compounds, the composite as well as the device architecture. Based on these findings, material and device parameters for a highly efficient bulk heterojunction device are presented.
Two crystal structures of PCBM, obtained from different crystallisation solvents, are presented; a proposed link with solvent dependence of the efficiency of MDMO-PPV:PCBM solar cells is described.
Ultrafast spectroscopic studies using an optical excitation of a conjugated polymer by sub-10-fs pulses are reported. Phonon modes which are strongly coupled to the electronic excitation of the ...conjugated polymer are directly observed as coherent oscillations during the pump–probe experiment, mirroring the resonant/nonresonant Raman spectrum of the conjugated polymer. In composites of a conjugated polymer with a fullerene the primary photoexcitation is found to be an ultrafast photoinduced electron transfer. We are able to time resolve for the first time the kinetics of this charge transfer process with a forward transfer time of around
τ
ct∼45 fs.
ELI-Beamlines (ELI-BL), one of the three pillars of the Extreme Light Infrastructure endeavour, will be in a unique position to perform research in high-energy-density-physics (HEDP), plasma physics ...and ultra-high intensity (UHI) (>1022W/cm2) laser–plasma interaction. Recently the need for HED laboratory physics was identified and the P3 (plasma physics platform) installation under construction in ELI-BL will be an answer. The ELI-BL 10 PW laser makes possible fundamental research topics from high-field physics to new extreme states of matter such as radiation-dominated ones, high-pressure quantum ones, warm dense matter (WDM) and ultra-relativistic plasmas. HEDP is of fundamental importance for research in the field of laboratory astrophysics and inertial confinement fusion (ICF). Reaching such extreme states of matter now and in the future will depend on the use of plasma optics for amplifying and focusing laser pulses. This article will present the relevant technological infrastructure being built in ELI-BL for HEDP and UHI, and gives a brief overview of some research under way in the field of UHI, laboratory astrophysics, ICF, WDM, and plasma optics.
Thermographic methods are widely established to detect shunts in photovoltaic technologies. In all methods the cell has to be directly accessible to determine quantitative shunt values. In this ...manuscript a precise method is presented to determine shunt values in solar modules consisting of series connected bulk-heterojunction organic solar cells without the need to access the single cells separately. It will be shown that, although parallel resistances in organic solar cells show a strong dependence on the illumination intensity, the shunts that are detected using illuminated lock-in-thermography are strongly ohmic and therefore can be assigned a distinct ohm value.
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•Contactless shunt determination by illuminated lock-in-thermography.•Current flow towards the shunt, resulting in increased power loss from the defect in open circuit conditions.•Simulation of the light intensity dependent power losses at shunts.•Correlation between the measured thermography signals and the simulated power losses.•Applicable for series connected with several solar cells.
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