In a three-time tariff the unit price differs between day, peak and night bands; night is usually the cheapest and peak the dearest. Because a eutectic plate stores cold, you can consume the electricity at whatever hour you like and use the cold the next day; in a directly cooled body the cold has to be made on the spot.
Example: with a freezing load of 40 kWh a day and a gap of p TL per kWh between night and peak, the yearly gain is 365 x 40 x p TL. Prices are in the tariff table and consumption by band is on your bill.
For GEBHARDT plates the freezing temperature must be at least 5 °C below the melting point; for a plate melting at -21 °C the recommended freezing temperature is -26 °C, and the time runs from 8 to 24 hours depending on the cooling technology. If your night band is shorter than that, part of the load falls into other bands.
Shifting is limited by cabinet and rack capacity, the shift that loads the plates, the subscription change and the power drawn when several cabinets run at once.