Gee, $7,000 seems like a lot just to run a refrigerator.
$7,000 is pretty expensive but again that figure has to be balanced over the lifetime of the kit in question. Assuming a 20 years operational lifetime means an annualised cost of $350 per year.
A typical chest freezer of around 8 cubic feet (energy A+ rated) would cost me around £350 or $600, with its energy consuption stated at 223 kWhr/year or 610 Whr/day or about $100 per year in electricity running costs.
looking again at the
http://www.sundanzer.com/PDF/residential_system_sizing.pdf energy usage table this would assume an ambient temperature of 76F assuming similar insulation properties.
The $7000 figure was based on the 100F ambient so if the conventional on grid freezer was used in a continual 100F temperature the energy consumption would I suspect be around double that so a 450-500 KWh/year figure would be more typical. i.e. its electricity costs would be $200 per year to run. The difference being $150 per year in addition to the operational cost of the grid tied freezer over that 20 year operational period.
You could see that additional cost of $150/year over the 20 year period as an insurance policy against grid failure and the consequences of no refrigeration facilities. The solar PV and battery system can also of course be used for additional emergency measures because the $7000 PV refrigeration system can also be used to power other devices in the event of an emergency or long term grid failure which takes higher priority over domestic refrigeration.