optimum panel for 85 amp battery

[Skvez]

Lets assume you have a freezer with an A rating for efficiency and it consumes about 325 kWh/year (about typical for an A rated freezer).

Lets assume it runs about 1/3 of the time (mine seems to keep adequately cool only running 8 hours a day)
So that’s about 2920 hours a year
Or 111W when running

So your 300W inverter could run it but might struggle to start it as starting surges can easily be 3 times the running load.

Lets assume you meant an 85Ah battery

If you don’t want to take it below 80% that 20% power to work with which is 17Ah @ 12V = 204Wh

111W at 204Wh is just under 2 hours (ignoring efficiently losses which we really shouldn’t as they could be 30%).

The problem here isn’t what panel you use or what inverter you use the problem is that fridges require *big* battery banks to operate.
No matter what size of solar panel you had, if you got two or three cloudy days in a row your freezer would defrost.

It’s just not practical for most of us to expect to operate a fridge or freezer in a grid down situation off battery power. If you really need a fridge/freezer (for instance if you are diabetic and need to keep you insulin cool) I suggest you look at gas powered fridge and get a big gas tank.

On the other hand that battery will be comfortable running LED lights for many days between charges.