Optimizing Solar Panel Placement through Passive Architectural Design

Abstract

Traditional wisdom has dictated that in the Northern Hemisphere, residential rooftop photovoltaic (PV) systems should be facing true south when possible to maximize energy production. However, an abundance of south-facing PV systems in communities generating power simultaneously at peak solar times has caused excessive reverse power flows which introduce multiple challenges within the broader power grid. At the aggregate level, this has caused sharp ramps in generation at sunrise and sunset, created challenges for grid reliability, and introduced local grid issues like voltage spikes. As a result, utilities have begun to reduce payments to customers for feeding solar generation back to the grid, moving away from so-called net-metering schemes. This has incentivized west-facing solar panels to better overlap with typical residential demand, reducing reverse flows, but it remains unclear as to how best to choose orientation of panels to achieve community-level goals like self-reliance (e.g., in the case of a microgrid) while minimizing the amount of battery capacity required. In this paper, we consider a community-level design problem for the optimal placement of residential rooftop solar panels considering different home designs and demand patterns. We develop a flexible simulation testbed that solves a mixed-integer linear optimization problem to determine, given a particular community-level objective, the orientation of panel placement within the restrictions of roof geometry and space. The results indicate that optimal placement can help a community maximize self-consumption, facilitating a transition to subhourly net-zero energy goals and reducing the need for energy storage. The following paper includes a novel optimization objective for designing solar panel installations. Whereas historically solar installers have emphasized maximization of solar power generation, utilities have begun to push back on excess power production from so-called prosumers (customers who also generate power) during peak solar production hours. Our proposed objective is to maximize the amount of usable solar power rather than the potential solar power. Solar power that is temporally offset from the conventional south-facing peak production can lessen the impacts of ramp down and ramp up periods. The models presented in this paper result in an optimal ratio of solar panel orientation for a given demand profile and location. We suggest that developers use this information to create a temporally robust solar generation profile in the community. The existing (or designed) roof profiles of a community can be input to the optimization constraints with a limited number of solar panels. The resulting profile assists in reducing the need for rapid ramp up and ramp down capacity as well as reducing battery storage capacity in the event that the community operates in an islanded microgrid mode.