A Tool for Optimizing Unit Configuration of Heat Pump Water Heater System with a Storage Battery

Abstract

Heat pump water heaters (HPWHs) are one of the key technologies for reducing CO₂ emissions from the household sector and must be downsized to expand their use in high density urban areas. Though the reduction of tank capacity is vital for downsizing HPWH, this often increases operation costs because it means heat pumps must boil water with expensive electricity during the day in order to avoid running out of hot water. Consequently, the development of a heat pump water heater with a storage battery (HPWH-SB) was investigated. In this paper, we develop an optimizing unit configuration tool that finds the optimal combination of heat pump, storage tank, and storage battery and estimate battery break-even point.