; and (ii) is designed, marketed, or shipped from the manufacturer with a capability of operating or being configured to operate at inputs greater than, equal to, or below 12 kilowatts. (D) Solar thermal-assisted electric storage unit The term solar thermal-assisted electric storage unit means a unit that— (i) has an input of 12 kilowatts or less; (ii) has at least 2 dedicated ports in addition to the ports used for introduction and delivery of potable water for the supply and return of water or a heat transfer fluid heated externally by solar panels; (iii) does not have electric resistance heating elements located in the lower half of the storage tank; (iv) has the temperature sensing device that controls the auxiliary electric heat source located in the upper half of the storage tank