Novel load matching indicators for photovoltaic system sizing and evaluation

Abstract

Integration of renewable energy sources in energy systems is crucial in achieving climate goals. Transformation of the power system – decentralization and prosumerism has led to the spread of domestic power plants taking part in the process. Mismatch problem of these predominantly grid-connected systems are typically described with load matching indicators. Most commonly used self-consumption and self-sufficiency metrics, though come with limits. One of the greatest is that they are monotone as the function of the capacity of photovoltaics implemented, making them uncapable of suggesting a technical optimum for system size. The scope of this study is to introduce two novel indicators with technical optima those can serve as a sizing principle for domestic photovoltaic plants for different approaches. First, self-production metric is introduced which allocates photovoltaic capacity that delivers maximum renewable utilization on-site and second, grid-liability reveals an optimum from the perspective of minimizing grid usage.A reference building is studied with two control approaches to observe both the existing and indicators. As a base scenario, a water heater with classical control is simulated, while in the second case, demand side management is achieved via improved rule-based control, aiming to store surplus photovoltaic power production. Simulations reveal that the optimum capacity of the photovoltaics from the perspective of both self-production and grid-liability is much lower than the capacity (of 6.57kWp) that would cover the annual electricity demands of the observed household. In case of the traditional control, self-production leads to an optimal photovoltaic capacity of 4.38kWp, while grid-liability to a 0.73kWp. With improved control, optimal capacities are much closer, 2.92and 2.19kWp respectively.