As variable renewable energy resources such as solar photovoltaic (PV) and wind power provide an increasing portion of electricity to the grid, new forms of demand response are being developed with capabilities of reserve provision and frequency control. Thermostatically controlled loads such as air-conditioners are suitable to control frequency deviation and imbalance of power systems. First in this paper, power consumption was modeled based on measured dynamic characteristics of residential air-conditioners by changed indoor temperature setting in an experimental smart house, COMMA house. Then, this paper discusses how much the air-conditioners are able to reduce or increase power consumption as the potential of demand flexibility by turning on or off. The potential is estimated by using the model with considering residential comfort. As the result, there are some characteristics about the potential depending on, the seasons, air-conditioners’ starting up at each time of day and heat loss coefficient. Finally, the potential are compared with the PV output fluctuation under large PV penetration. The comparison shows the least potential in February is 34 % of PV output fluctuation while the least potential in April is the 2 % of PV output fluctuation.

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