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- All Subjects: Performance
- Creators: College of Health Solutions
- Creators: Rogers, Bradley
- Status: Published
Characterization and analysis of long term field aged photovoltaic modules and encapsulant materials
Part 1 characterizes soiling losses using various techniques to understand the effect of soiling on photovoltaic modules. The higher the angle of incidence (AOI), the lower will be the photovoltaic (PV) module performance. Our research group has already reported the AOI investigation for cleaned modules of five different technologies with air/glass interface. However, the modules that are installed in the field would invariably develop a soil layer with varying thickness depending on the site condition, rainfall and tilt angle. The soiled module will have the air/soil/glass interface rather than air/glass interface. This study investigates the AOI variations on soiled modules of five different PV technologies. It is demonstrated that AOI effect is inversely proportional to the soil density. In other words, the power or current loss between clean and soiled modules would be much higher at a higher AOI than at a lower AOI leading to excessive energy production loss of soiled modules on cloudy days, early morning hours and late afternoon hours. Similarly, the spectral influence of soil on the performance of the module was investigated through reflectance and transmittance measurements. It was observed that the reflectance and transmittances losses vary linearly with soil density variation and the 600-700 nm band was identified as an ideal band for soil density measurements.
Part 2 of this thesis performs statistical risk analysis for a power plant through FMECA (Failure Mode, Effect, and Criticality Analysis) based on non-destructive field techniques and count data of the failure modes. Risk Priority Number is used for the grading guideline for criticality analysis. The analysis was done on a 19-year-old power plant in cold-dry climate to identify the most dominant failure and degradation modes. In addition, a comparison study was done on the current power plant (framed) along with another 18-year-old (frameless) from the same climate zone to understand the failure modes for cold-dry climatic condition.
Part 1 of this thesis determines the most dominant failure modes of field aged photovoltaic (PV) modules using experimental data and statistical analysis, FMECA (Failure Mode, Effect, and Criticality Analysis). The failure and degradation modes of about 5900 crystalline-Si glass/polymer modules fielded for 6 to 16 years in three different photovoltaic (PV) power plants with different mounting systems under the hot-dry desert climate of Arizona are evaluated. A statistical reliability tool, FMECA that uses Risk Priority Number (RPN) is performed for each PV power plant to determine the dominant failure modes in the modules by means of ranking and prioritizing the modes. This study on PV power plants considers all the failure and degradation modes from both safety and performance perspectives, and thus, comes to the conclusion that solder bond fatigue/failure with/without gridline/metallization contact fatigue/failure is the most dominant failure mode for these module types in the hot-dry desert climate of Arizona.
Part 2 of this thesis determines the best method to compute degradation rates of PV modules. Three different PV systems were evaluated to compute degradation rates using four methods and they are: I-V measurement, metered kWh, performance ratio (PR) and performance index (PI). I-V method, being an ideal method for degradation rate computation, were compared to the results from other three methods. The median degradation rates computed from kWh method were within ±0.15% from I-V measured degradation rates (0.9-1.37 %/year of three models). Degradation rates from the PI method were within ±0.05% from the I-V measured rates for two systems but the calculated degradation rate was remarkably different (±1%) from the I-V method for the third system. The degradation rate from the PR method was within ±0.16% from the I-V measured rate for only one system but were remarkably different (±1%) from the I-V measured rate for the other two systems. Thus, it was concluded that metered raw kWh method is the best practical method, after I-V method and PI method (if ground mounted POA insolation and other weather data are available) for degradation computation as this method was found to be fairly accurate, easy, inexpensive, fast and convenient.
Recovery from exercise has become an evolving aspect of all sports performance. Increased research has led numerous individuals to understand and utilize the modalities that have become available. Methods such as Cold Water Immersion (CWI), Contrast Water Therapy (CWT), and Hot Water Immersion (HWI) are some of the modalities growing in popularity as well as utilization by athletes across all sports. This paper aims to examine and analyze evidence across several research journals that evaluate the effectiveness and also application of these recovery methods. Cold and heat exposures on the body can have a drastic positive impact on athletic performance. However, without the correct knowledge and guidance, these methods can augment, mitigate, and even diminish the effects of adaptation and exercise. This thesis aims to examine research journals and extract specific practices based on empirical evidence. This is to form proper deliverables and protocols for athletes to use for ideal adaptations and recovery for performance.
This thesis reviewed variables of baseball mechanics and performance as discussed in current literature. This included investigating factors of biomechanics, the health of players, and comparisons across demographics. At the biomechanical level, components of the kinetic chain were observed as the energy transferred from the lower body to the upper body. Additionally, the upper body appeared to compensate for deficits in the rotation of the trunk. Injuries to the abdominal and low back were correlated with trunk rotation, while arm injuries were traced back to overuse and fatigue. When considering experience level, variation tended to decrease. Youth players demonstrated different patterns of fatigue and different injury correlates compared to adults. At a geographic level, American pitchers may be associated with an increased risk of elbow injuries, with Japanese and Korean pitchers to shoulder injuries; these differences are thought to be due to differences in instruction. Applying this research and findings to current baseball players may help guide training and performance or continue research.