I am starting a new company with several of my friends. We have used my house (2800 square feet two level house in Yonkers, NY) for learning on how to be less dependent on fossil fuel to heat the house. We installed a hydronic radiant heating for the upper and lower level using ½” and ¾” HydroPex tubing. Since it was too much work we decided to have a company to install the solar water heating in order to supplement the electric water heater we are using. We have six solar panels facing south on the roof and a 200 gallons water tank heated by the sun through those panels and glycol circulating in a closed loop with a 50 gallons whirlpool electric tank as a back up.  However, electricity is much more expensive now here in Yonkers than one year ago. Moreover when the temperature is below freezing the 200 gallons water solar tank/ 50 gallons water Whirlpool electric tank is not enough to heat the whole house. Therefore, we are planning to use a reverse-chiller for water heating which is less expensive than either gas or oil; however, it uses some electricity. Could someone tell me if it would be cost-effective to install a reverse chiller?