If you live in Arizona and hook up a battery and leave it out in the sun all week and only use it on weekends.
Look at your juicer and see how much energy it uses.
Look at the USGS web site for the solar gain figures for your location.
Look at the specs for the system and see what the % conversion efficiency to expect.
Divide the total current flow hours needed by the solar gain then multiply by the % efficiency to get the time you need to run the solar system to get the needed power. Don’t forget to multiply by the efficiency percentages of each device in your system. This tells you how much battery you need and how long you need to run the charger.
Don’t forget to allow for low energy days!