If I could get a 50% discount on power at night up north I'd be heating all my domestic water then and even checking into the economics of a battery bank. If I knew that rate would apply for awhile I'd look into geothermally heating a whole lot of water and then running it through a fan coil in the ductwork or a radiant floor during peak times. Might even consider chilling and storing water for summer AC.

I was thinking the same thing