Modeling Off-Grid Photovoltaics Integrated with Micro-Cogeneration and Electrical Energy Storage

Abstract

Due to the elevated expenditure of fossil fuels and their adverse impacts on climate change resulting from greenhouse gas emissions, it is imperative to integrate clean energy sources alongside fossil fuels. This study presents the design, simulation, and optimization of an integrated system comprising solar photovoltaics, micro-cogeneration, and electrical energy storage to achieve energy self-sufficiency for a single-family house in Wynnewood, PA. The study determines the maximum cost of the micro-cogeneration converter that can be economically added to the heating system, enabling it to generate both heat and electricity simultaneously. The modeled system needs to meet all required electricity and heat demands of the house for a year with minimum outages. We considered a range of alternatives for the capacity of PV panels, batteries, and converter, resulting in varied electricity costs, all of which are significantly higher than the electricity cost when connected to the grid. Specifically, for the analyzed household, the minimum cost is approximately 55 cents per kilowatt-hour of consumed electricity, which is achieved using micro-cogenerator converters that have approximately 4% efficiency. In contrast, for a system that does not include any co-generation (i.e., a system with PV and battery only), the electricity would cost approximately 71 cents per kilowatt-hour. We also found that the micro-cogeneration converter can be a cost-effective addition to off-grid houses even when the converter costs up to $20 per Watt of rated output power but only for converter efficiencies of a few percent. Such high costs of converters are tolerable because they produce enough power to cover the wintertime deficit in the production of PV panels.