Interconnect resistance of photovoltaic submodules

Small area amorphous silicon solar cells generally have higher efficiencies than large interconnected submodules. Among the reasons for the differences in performance are the lack of large area uniformity, the effect of nonzero tin oxide sheet resistance, and possibly pinholes in the various layers. Another and usually small effect that can contribute to reduced performance of interconnected cells is the resistance of the interconnection i.e., the series resistance introduced by the metal to tin oxide contact through silicon. Proper processing problems to avoid poor contacts are discussed

Uniform, High Efficiency, Hybrid CIGS Process with Application to Novel Device Structures: Annual Technical Report, 15 March 2005 - 14 March 2006

One of the main Phase I objectives of this subcontract was for EPV to demonstrate 14%-efficient CIGS devices using a hybrid process. The processing was also required to have good control ability. These goals were successfully accomplished. It will be seen that during Phase I, we successfully developed a new, simplified hybrid process. A highlight of intensive work was the achievement of a 14.0% NREL-verified device at a CIGS thickness of 1.13 ..mu..m. The simplified hybrid process considerably reduces CIGS film formation time and offers the promise of being a truly cost-effective and manufacturable one. It is considered to be one of the more attractive CIGS processes in the industry

Thin-Film CIGS Photovoltaic Technology: Annual Technical Report-Phase II, 16 April 1999-15 April 2000

A summary of Energy Photovoltaics' Phase II work includes the following: (1) EPV has demonstrated that it can sputter a Mo back-contact capable of supporting very high efficiency cell processing. Using EPV Mo, NREL has deposited a 17.1% CIGS cell (no AR coating). EPV believes it can identify the signature of ``good'' Mo. The Mo was produced on EPV's 0.43 m{sup 2} pilot-line equipment; (2) EPV has performed compound synthesis for several classes of materials, namely non-Cu precursor materials, Cu-containing materials, and ternary buffer materials. Using a ternary compound synthesized at EPV (ZIS) as an evaporation source material for the buffer layer, a Cd-free CIGS device has been produced having an efficiency of 11.5% (560 mV, 32.1 mA/cm{sup 2}, FF 64.3%). The ZIS films are photoconductive, and the devices exhibit no dark-light crossover or light soaking effects; (3) EPV initiated the interest of the University of Oregon in capacitance spectroscopy of CIGS devices. An Urbach tail with characteristic energy E0 < 20meV was identified by transient photocapacitance spectroscopy; (4) Small-area CIGS devices were produced in the pilot-line system with an efficiency of 12.0% (581 mV, 30.1 mA/cm{sup 2}, FF 68.7%), and in an R and D-scale system with 13.3% efficiency (569 mV, 34.1 mA/cm{sup 2}, FF 68.1%); (5) An improved linear evaporation source for Cu delivery has been developed and was used for CIGS formation in the pilot-line system. The deposition width is 45 cm. This technological ``tour de force'' allows EPV to build large-area CIGS systems possessing considerable flexibility. In particular, both EPV's FORNAX process and NREL's 3-stage process have been implemented on the pilot line. A CIGS thickness uniformity of 7% over a 40 cm width has been achieved; (6) A 4-head linear source assembly was designed, constructed, and is in use. Flux monitoring is practiced; (7) Large-area CIGS modules were produced with Voc's up to 36.3 V; (8) EPV has started to construct an entirely new CIGS pilot line for scale-up and limited manufacturing purposes. The coating width will be 65 cm; (9) The company's analytical capabilities are currently being upgraded with the installation of ICP and SEM/EDS facilities

Thin-Film CIGS Photovoltaic Technology; Annual Technical Report, Phase I; 16 April 1998 - 15 April 1999

This report describes work performed by Energy Photovoltaics, Inc. (EPV) under Phase I of this subcontract. EPV's new FORNAX process for CIGS formation is capable of producing devices with high V{sub oc} (>600 mV) and no dark aging effects. Parameters of the best device so far are V{sub oc} = 611 mV, J{sub sc} = 27.5 mA/cm{sup 2}, FF = 74.5%, and efficiency = 12.5%. A 34-cm{sup 2} 16-cell minimodule was produced using FORNAX CIGS with V{sub oc} = 9.58 V, I{sub sc} = 52.0 mA, FF = 69.8%, and efficiency = 10.2%. A new version of EPV's linear evaporation source was developed with improved rate and uniformity for Cu deposition over a width of 45 cm. Using the new linear source, the FORNAX process was implemented on 0.43-m{sub 2} substrates in EPV's CIGS pilot line, with V{sub oc} = 537 mV and FF = 70.3% being achieved on a device. The EPV Subteam of the National CIS R&D Team has produced Cd-free ZnO/CIGS devices on NREL CIGS using the ROMEAO process (reaction of metal and atomic oxygen) for ZnO deposition. After soaking, the best device exhibited a V{sub oc} of 565 mV and an efficiency of 12.3%. Novel bias drive methods were devised for field soaking/anti-soaking experiments as a function of time and temperature. Scaling laws and an activation energy of 0.51 eV were found. Thermally stimulated capacitance reveals the existence of three distinct contributions to ZnO/CIGS device capacitance, two appearing to be gap-state effects and one related to net doping concentration. The coating time of the sputtered pilot-line ZnO:Al has been reduced by a factor of 3 while maintaining film quality. The deposition rate is 48 A s{sup -1}. Plans are under way to increase the substrate size from 0.43 m{sup 2} to 0.79 m{sup 2}

Pregabalin versus gabapentin in partial epilepsy: a meta-analysis of dose-response relationships

<p>Abstract</p> <p>Background</p> <p>To compare the efficacy of pregabalin and gabapentin at comparable effective dose levels in patients with refractory partial epilepsy.</p> <p>Methods</p> <p>Eight randomized placebo controlled trials investigating the efficacy of pregabalin (4 studies) and gabapentin (4 studies) over 12 weeks were identified with a systematic literature search. The endpoints of interest were "responder rate" (where response was defined as at least a 50% reduction from baseline in the number of seizures) and "change from baseline in seizure-free days over the last 28 days (SFD)". Results of all trials were analyzed using an indirect comparison approach with placebo as the common comparator. The base-case analysis used the intention-to-treat last observation carried forward method. Two sensitivity analyses were conducted among completer and responder populations.</p> <p>Results</p> <p>The base-case analysis revealed statistically significant differences in response rate in favor of pregabalin 300 mg versus gabapentin 1200 mg (odds ratio, 1.82; 95% confidence interval, 1.02, 3.25) and pregabalin 600 mg versus gabapentin 1800 mg (odds ratio, 2.52; 95% confidence interval, 1.21, 5.27). Both sensitivity analyses supported the findings of the base-case analysis, although statistical significance was not demonstrated. All dose levels of pregabalin (150 mg to 600 mg) were more efficacious than corresponding dosages of gabapentin (900 mg to 2400 mg) in terms of SFD over the last 28 days.</p> <p>Conclusion</p> <p>In patients with refractory partial epilepsy, pregabalin is likely to be more effective than gabapentin at comparable effective doses, based on clinical response and the number of SFD.</p

Effects of Lycopene on the Initial State of Atherosclerosis in New Zealand White (NZW) Rabbits

BACKGROUND: Lycopene is the main carotenoid in tomatoes, where it is found in high concentrations. Strong epidemiological evidence suggests that lycopene may provide protection against cardiovascular diseases. We therefore studied the effects of lycopene on diet-induced increase in serum lipid levels and the initiation of atherosclerosis in New Zealand White (NZW) rabbits. METHODOLOGY/PRINCIPAL FINDINGS: The animals, divided into four groups of 9 animals each, were fed either a standard diet, a high-cholesterol diet containing 0.5% cholesterol, a high-cholesterol diet containing placebo beadlets, or a high-cholesterol diet plus 5 mg/kg body weight/day of lycopene (in the form of lycopene beadlets), for a period of 4 weeks. We found significantly elevated lycopene plasma levels in the animal group treated with lycopene beadlets. Compared to the high-cholesterol and the placebo group, this was associated with a significant reduction of 50% in total cholesterol and LDL cholesterol serum levels in the lycopene group. The amount of cholesteryl ester in the aorta was significantly decreased by lycopene. However, we did not observe a significant decrease in the extent of aortic surface lipid accumulation in the lycopene group. In addition, no differences in the intima-media thickness among groups were observed. Endothelial-dependent and endothelial-independent vasodilation in isolated rabbit aortic and carotid rings did not differ among any of the animal groups. CONCLUSIONS: Lycopene supplementation for 4 weeks increased lycopene plasma levels in the animals. Although we found strongly reduced total and LDL cholesterol serum levels as well as significantly lower amounts of cholesteryl ester in the aortae in the lycopene-treated group, no significant differences in initial lesions in the aortae were detected

A Common CNR1 (Cannabinoid Receptor 1) Haplotype Attenuates the Decrease in HDL Cholesterol That Typically Accompanies Weight Gain

We have previously shown that genetic variability in CNR1 is associated with low HDL dyslipidemia in a multigenerational obesity study cohort of Northern European descent (209 families, median  = 10 individuals per pedigree). In order to assess the impact of CNR1 variability on the development of dyslipidemia in the community, we genotyped this locus in all subjects with class III obesity (body mass index >40 kg/m2) participating in a population-based biobank of similar ancestry. Twenty-two haplotype tagging SNPs, capturing the entire CNR1 gene locus plus 15 kb upstream and 5 kb downstream, were genotyped and tested for association with clinical lipid data. This biobank contains data from 645 morbidly obese study subjects. In these subjects, a common CNR1 haplotype (H3, frequency 21.1%) is associated with fasting TG and HDL cholesterol levels (p = 0.031 for logTG; p = 0.038 for HDL-C; p = 0.00376 for log[TG/HDL-C]). The strength of this relationship increases when the data are adjusted for age, gender, body mass index, diet and physical activity. Mean TG levels were 160±70, 155±70, and 120±60 mg/dL for subjects with 0, 1, and 2 copies of the H3 haplotype. Mean HDL-C levels were 45±10, 47±10, and 48±9 mg/dL, respectively. The H3 CNR1 haplotype appears to exert a protective effect against development of obesity-related dyslipidemia