Make two energy budgets
Estimate a normal day and a tougher day with greater use and less charging. Include fridge, lighting, communications and occasional appliances. Record daily Wh and whether each device needs AC. Measure variable loads before the trip when possible.
Build reserve before adding solar
Multiply the tougher daily demand by days without dependable charging. Adjust nominal capacity for usable energy and losses. Treat the panel as variable charging, not a daily guarantee; shaded parking can change the plan. PVWatts helps with local scenarios but cannot predict your exact parking spot.
Verify the complete system
Check simultaneous output, outlets, solar input, connectors, ventilation and manufacturer limits. Plan an alternative charging source and decide which loads get priority. Start with the calculator, then read the battery and panel guides.
Frequently asked questions
How many days can I stay off-grid?
Divide usable battery energy by measured daily Wh, then account for charging and uncertainty. There is no universal number.