How do I figure out how much Power I need?
You can look on the devices label, usually it'll say how many watts it consumes. Let's say your fridge says it draws 200 watts. But you want watt-hours. Not all devices run 24×7, they turn on when they need too. Power draw can also be seasonal. The best way to get an idea is to measure it (e.g., a watt meter) in actual conditions. Link to more information. Example: you leave a watt-meter connected to your fridge for a week and it says you use an average of 107w/hr and a peak of 130w/hr.