Patent ID: 9557068
Date: 2017-01-31
CPC Classifications: F24D,F24H,G05D,Y02B

Claim:
1. A heat pump hot-water supply system, comprising a heat pump hot-water supply device, an electricity storage device, and a control device, wherein the control device determines an operating time zone of the heat pump hot-water supply device based on power conversion efficiency of the electricity storage device, coefficients of performance of the heat pump hot-water supply device of a current day and a next day, and an electricity rate structure of a commercial power system, further comprising a hot-water storage tank for storing hot water obtained by operating the heat pump hot-water supply device, wherein the electricity storage device converts an AC power supplied from the commercial power system into a DC power to store the DC power and also converts the stored DC power into an AC power to supply the AC power, and the control device further determines whether the electricity storage device is to be charged or not based on the power conversion efficiency of the electricity storage device, the coefficients of performance of the heat pump hot-water supply device of the current day and the next day, and the electricity rate structure of the commercial power system, wherein the control device is configured to compare a ratio of coefficients of performance with the power conversion efficiency of the electricity storage device, in accordance with the electricity rate structure wherein a nighttime electricity rate is lower than a daytime electricity rate, wherein the ratio of coefficients of performance is obtained by dividing a coefficient of performance of the heat pump hot-water supply device corresponding to an outside air temperature of the nighttime of the current day by a coefficient of performance of the heat pump hot-water supply device corresponding to an estimated value of an outside air temperature of the daytime of the next day, and wherein the control device either operates the heat pump hot-water supply device in the daytime of the next day by using power stored in the electricity storage device in the nighttime of the current day if the ratio of coefficients of performance is less than the power conversion efficiency or operates the heat pump hot-water supply device in the nighttime of the current day by using power supplied from the commercial power system if the ratio of coefficients of performance is equal to or greater than the power conversion efficiency.