Hi Gordon
The point is you have to make the conversion to ice at some stage during the running of the refrigerator. Yes refrigerators are not efficient, but neither are batteries. There is a loss from electricity to battery back to electricity.
Here I go from electricity to ice one step.
I have designed a microprocessor circuit from inexpensive bits to control the running of the 240V ice banks compressor directly from the panel.
Once the refrigerator has reached the ice banks holding capacity, the any excess energy is diverted to a 200Ah truck battery to supply my LED lighting and washing machine occasionally, thus reducing the need for a large battery bank.
I understand it is not easy to make ice. However ice is excellent energy storage medium, if you want cold. After heating, and hot water, running the refrigerator is the next in line for reducing home energy demand.
Thanks for the tip re the NaCl solution; it may help with the temperature reduction. Keeping the temperature of the fridge regulated is best done with mechanical device, or manually with hand flap control.
One good thing about using ice in place is I do not have to cart it about as they did back in the days of grandpa. Those old boxes would keep stuff cold for up to 5 days, I read.
The next trick is powering the fan at night, so I can sleep in this heat.
Cheers AlanJ