I'm still waiting for my Vestfrost SE255 to be delivered. Excellent article BTW. The simple analogue bang bang controller looks like it could be refined much further. Looks like another another PIC chip project so I can control the temperature of the Freezer and operate it as a Fridge or Freezer if need be from my ongoing solar project without voiding the warranty.

The inverter I have chosen is a WAECO SinePower MSP352/MSP354 which allows the inverter to be switched on and off remotely from the digital thermostat controller, with the possibility of implementing a 3-term temperature control law for tighter set point temperature regulation. The thermostat controller could even chill the fridge even cooler down to 1-2 C during the day when there is plenty of solar energy and draw down less energy during the night time so that the temperature rises slowly up to 5-6C overnight thus saving the lifetime of the battery array by minimizing deep cycling effects. A relay could also be used, so as to switch from the Solar Battery Array/inverter 240V source to mains if the batteries become too discharged.