Hybrid AC/DC and conventional AC house efficiency for net zero energy homes

Abstract

The transition toward net-zero energy homes (NZEH) requires residential electrical systems that can efficiently integrate renewable generation, battery storage, and both AC and direct current (DC) loads. Although DC and hybrid AC/DC residential systems have been widely studied, limited work directly compares hybrid AC/DC and conventional AC house architectures under different grid standards, power levels, and AC/DC load ratios while considering DC bus losses. This study presents a MATLAB/Simulink-based steady-state efficiency comparison between hybrid AC/DC and conventional AC residential electrical systems. Twelve models were developed, consisting of six hybrid AC/DC and six conventional AC configurations under 120 V/60 Hz and 230 V/50 Hz standards. The models include PV generation, battery storage, inverter, AC/DC converter, multiple-input single-output (MISO) converter, and line-resistance effects. Results show that hybrid AC/DC houses achieve 4-11% higher efficiency than conventional AC houses when DC load demand remains below approximately 1.5-2.0 kW, mainly due to reduced conversion stages. At higher DC load levels, the efficiency advantage decreases because of copper losses in the 48 V DC bus. Increasing the DC bus voltage to 60 V reduces current-related losses and extends the efficient operating range. These findings indicate that hybrid AC/DC distribution is most suitable for residential applications with low-to-moderate DC demand, such as lighting, electronics, communication devices, and other DC-compatible appliances. The main contribution of this study is identifying the operating range, efficiency limit, and practical design implications of hybrid AC/DC residential distribution for future NZEH applications.