Basic finger in the air sizing/scaling for solar applications is:
Calculate your total load over a day, then divide it to get the average watts. Multiply that wattage by 10. This is your panel size.
As an example if you have a load that runs at 100W for 30 minutes every hour, 24/7 then your average load is 50W. You would look for a 500W panel(s).
For battery size it depends on your location, how sunny it is and the location of the solar panel, but for the UK I try and aim for at least a week of intermittency to cover. So for the above example 50W for a week is about 8.4kWh of battery pack ( about 9 100Ah marine lead acids!).
On change controllers I use an EPEver 10A MPPT controller on my 50W panel and it consumes (along with an ESP8266 monitor sending data every 5 seconds) about 50mA. the charge controller itself draws about 30mA during the day and drop to 20mA or less when it goes into night mode. So when it's connected to a 100Ah marine battery it will run for about at least a month with no sunlight.
As a last resort, if mains power is available, you can connect a charger to the lead acid while it's connected to the charge controller and it shouldn't upset it. You can tigger this on a relay based on the battery voltage.