Strictly off grid: Given a specific load in watt-hours per day. Size your inverter to handle double the running watts plus surge current. Size your battery capacity to handle the loads watt-hours per day and double it for Lithium based batteries and triple it for Lead acid. Size your solar system to provide sufficient wattage to recharge the battery in a day + supply all the loads daily watt-hours, then multiply by 2.
Example: 1200wh daily load of a freezer that pulls 5 amps when running compressor.
Inverter size: Load is 5a x 120vac = 600 watts running > Inverter minimum would be 1200 watts.
Battery size: 1200wh X 2 for lithium would be a 2400wh battery, For lead acid X 3 would be 3600wh
Solar panels: Daily watt-hours of load and battery(1200wh + 1200wh to recharge battery = 2400wh) divide by average hours of sun for your location, lets say 5 hours, to get watts worth of panels X 2 (2400/5 *2) = 960 watts worth of panels
Now toss in a small gas generator when the weather refuses to co-operate.
If someone has a better and more accurate way to figure this please comment.
Example: 1200wh daily load of a freezer that pulls 5 amps when running compressor.
Inverter size: Load is 5a x 120vac = 600 watts running > Inverter minimum would be 1200 watts.
Battery size: 1200wh X 2 for lithium would be a 2400wh battery, For lead acid X 3 would be 3600wh
Solar panels: Daily watt-hours of load and battery(1200wh + 1200wh to recharge battery = 2400wh) divide by average hours of sun for your location, lets say 5 hours, to get watts worth of panels X 2 (2400/5 *2) = 960 watts worth of panels
Now toss in a small gas generator when the weather refuses to co-operate.
If someone has a better and more accurate way to figure this please comment.