Solar wharf garage

Abstract

The growing electrification of leisure boats has engendered the need for accessible marine charging stations. Since many marinas lack the infrastructure necessary to accommodate large numbers of electric boats, local charging solutions are required. This project was to feature the iterative design of an electric boat charging structure with photovoltaic systems, in this project called Solar Wharf Garage, that could be implemented into existing marinas. The overall objective was to generate a creative and feasible solar wharf garage design supported by objective engineering analysis. This required extensive research of electric boats, photovoltaic systems, wharf design, and material selection. Initially, the most important customer needs were gathered from the client Volvo Penta, including boat power requirements, modularity expectations, and environmental resilience. To begin research, site visits were conducted to marinas and solar energy system providers, that gathered information on marina layouts and commercial solar systems. Thereafter, functional requirements were generated followed by a list of 12 engineering specifications based on the customer needs and literature review. In the concept generation phase, the team iteratively created 30 concepts to address each functional requirement and evaluated these concepts to understand their limitations and explore possible solutions. The performance of each concept was ranked in a Pugh matrix relative to a standard Swedish boathouse and later a generated concept. The highest scored concepts were then evaluated in a Kesselring Matrix relative to an ideal performance for each functional requirement. With only one remaining concept, the work continued in focus groups to develop the different subsystems of the final design. The expected solar panel efficiency was simulated using the System Advisor Model (SAM) software in order to find the energy output capabilities of the system as well as the photovoltaics’ financial feasibility. A thorough mechanical analysis of the design was also completed to calculate the expected applied stress on the garage structure with the chosen aluminum alloy 6061-T6 AA. Lastly, evaluation were done regarding the expected success of the final concept in satisfying the original 12 engineering specifications. The resulting design is a twoboat- garage that generates sufficient electric energy for weekly outings - approximately 5.074 kWh annually. The photovoltaic system design uses two 9-panel strings, mounted flat, with each string of panels wired in series to one grid-tied inverter. The solar panels of the system can be retracted towards the dock for maintenance, removal, or off-season storage. Any excess electricity is fed back into the grid in exchange for credits, which reduce future electricity payments. The payback period of the photovoltaic system is approximately 13 years, which is roughly half of its estimated product lifespan.