Understanding the potential for electricity savings and assessing feasibility of a transition towards DC powered buildings

摘要

Advances in semiconductor power electronics and growing direct current (DC) loads in buildings have lead researchers to reconsider whether buildings should be wired with DC circuits to reduce power conversions and facilitate a transition to efficient DC appliances. The feasibility, energy savings, and economics of such systems have been assessed and proven in data centers and commercial buildings, but the outcomes are still uncertain for the residential sector. In this work, we assess the technical and economic feasibility of DC circuits using data for 120 homes in Austin, Texas to understand the effect of highly variable demand profiles on DC-powered residences, using appliance-level use and solar generation data, and performing a Monte Carlo simulation to quantify costs and benefits. Results show energy savings between 10–21 % when solar PV is distributed to all home appliances. When battery storage for excess solar energy is considered, these savings increase to 13–23 %. At present DC equipment prices, converting all equipment to DC causes levelized annual costs of electricity to homeowners to roughly double. However, by converting only homes’ air conditioning condensing units to DC, the costs of implementing DC circuits are greatly reduced and home energy savings of 7–17 % are generated. In addition to quantifying savings, we find major nontechnical barriers to implementing DC circuits in homes. These include a lack of standards for such systems, a relatively small market for DC appliances and components, utility programs designed for alternating current (AC) power, and a workforce unfamiliar with DC. Experience with DC is growing in other sectors, and with time this will be transitioned to a broader audience of engineers, electricians, and building inspectors to ensure that not only are the systems themselves safe, but that the image of direct current circuits becomes less foreign over time. Direct current may very well have a place in the residential sector, and research and development should continue to explore other potential benefits that might make a stronger case for a more widespread transition to what now appears a promising technology.