Photovoltaic characterization and trans-oceanic sub-surface photovoltaic performance

• Main Author: Krawczyk, Collin Anthony
• Format: Thesis
• Language: English
• Published: 2021
• Subjects: TJ Mechanical engineering and machinery; Elephant Seals; Alaska; Aleutian Islands
• Online Access: https://openknowledge.nau.edu/id/eprint/5640/; https://openknowledge.nau.edu/id/eprint/5640/1/Krawczyk_2021_photovoltaic_characterization_trans-oceanic_sub-surface_.pdf

Utilization of marine photovoltaic energy is primarily focused on surfaceharvesting with limited photovoltaic cell implementation in a submarine environment. To obtain estimations of photovoltaic energy in the submarine environment, an experimental deployment of solar cells was utilized. This deployment involved the development of custom photovoltaic assessment modules (CPAMs). These CPAMs were affixed to four adult female northern elephant seals (Mirounga angustirostris) with deployment times between 76 and 107 days. These deployments encompassed a large geographic area between Santa Cruz, California and the Aleutian Islands of Alaska. This work discusses the calibration, dive shifting, and power calculations of these oceanic deployments. Deployment results, including power results and energy predictions from the CPAM data record, are presented up to 22 meters in depth. Past this depth, depths fell below the sensitivity of the data resulting in a non-uniform distribution of high, medium, and low irradiances. However, this deployment relied on nonlinear regression to obtain power at depth and in low-light conditions, this regression did not produce accurate estimations of power. To include these low-light level cases, experimental laboratory characterization was conducted. While photovoltaic cells have been deployed in the marine environment in the past to assess performance at depth, unfortunately, these applied studies have been somewhat limited in their scope due to the environmental conditions at the test location. The results of silicon solar cell testing in a laboratory setting wherein the spectra produced by various water types are simulated over a wide range of depth and temperature are also presented. Spectra at depth were generated based on Bird's Clear Sky model and Jerlov's spectral absorption coefficients. These spectra were used in conjunction with a tunable solar simulator, source meter, and cold plate. This work discusses the spectra generation, experimental testing, and current-voltage curve parameters of silicon solar cells. The results include short circuit current, open circuit voltage, and maximum power at ten different water types with depths up to 30 m. While deeper depths could have been conducted, only depths up to 30 m were considered to limit the number of testing cases. This laboratory characterization provided an interpolation table to obtain power estimations for low-light conditions within the field deployment. It was found that there was a roughly 70-85% reduction in power within the first 5 m and 85-95% reduction in power at 15 m, comparable to previously published literature. Depending on solar cell size, energy requirements, and energy behavior of a bio-logger, solar energy can be a primary or supplementary energy source.