So if you plan on building 4KW solar, and then decide to do 100X that, you can generate ~1800KWH per day (400 * 5 hours per day of ideal sun * fudge factor). If you have the battery storage for that you can probably get through 66 days from one sunny day. The cost would be super prohibitive too, but not everyone needs 100X out there solar to get through some rough days.

My personal plan is 30KW (over the next few years) so I can get through like 4 days. And heck, a stormy day will still generate enough electricity.