For the internal coil application- I am really careful about the residual heat from the mash tun itself.
Also, i like to use a 2 stage cooling- first stage cools mash to 150F, then use a chiller and reservoir for second stage.
Pictured is evaporative glycol cooler that I have used on large apps for first stage- expensive now, but for multiple mash runs per week, helps on power usage using a fan to do the work rather than a refrigeration system, but the first cost is a doozey for a 3-5 year payback.
Typical for a Northern climate, a chiller and drycooler each with its own circulator attached to an internal plate exchanger to make cold water for the cold water reservoir. Customer uses the drycooler alone from September to March up in the Western CT mountains. Chiller is 10 Ton, Drycooler is 6 Ton nominal (12 ton, at least, in winter).
Who knows what KW cost will be in the next year.
Mike