Modeling and testing solar power for globally migrating submarine systems

Terrestrial sensor systems and platforms regularly rely on photovoltaic cells as their primary power source. With a rechargeable battery backup, solar modules provide these remote sensor systems with reliable, simple, and predictable power. For these terrestrial systems, power predictions are well established and engineers developing power budgets have multiple avenues for estimating daily average energy production. The same is not true for sensor systems in the marine environment. The lack of predictive methods for solar power is a major contributing factor to the nearly exclusive reliance on fixed charge batteries as the power source for submarine sensor systems and their platforms. The inability to harvest energy during a deployment limits deployment durations and data collection for these marine systems. Our group has worked to develop a method of predicting photovoltaic power production in the marine environment and recently conducted a deployment of a custom solar measurement module in order to validate and refine the model. In April of 2017 the module was deployed on a female northern elephant seal (Mirounga angustirostris) as it swam from Monterey, California, USA to Año Nuevo, California, USA. Current-voltage solar cell characterization curves were recorded throughout the deployment. Then, based on animal telemetry records, the solar assessment model was used to predict cell performance and the results were compared here to the cell performance recorded by the datalogging unit. Agreement was found between the modeled and measured data, with variations due to assumptions concerning model inputs.