How this is calculated
Usable Wh is watts × hours for every checked device, added together, then multiplied by your days of autonomy — the total energy the station has to hold and deliver with zero recharge.
Continuous W is every checked device’s running watts added together, on the assumption they could all be on at once. Surge W is not the sum of every device’s surge rating — loads don’t all start at the same instant — it’s that same continuous total plus the extra kick of whichever single motor has the biggest surge-minus-running gap, almost always the fridge or a power tool. That’s the number that actually trips an undersized inverter.
Recommended panel size divides one day’s Wh by your region’s average peak-sun-hours, then applies a realistic 25% derate for wiring, angle, temperature and inverter losses — the same derate used across Grid CEO’s sizing guides. It targets a full daily refill and doesn’t grow with your autonomy setting — more days of autonomy sizes a bigger battery, not a bigger panel.
- Panel wattage refills one day’s use, not your whole autonomy reserve — that’s what the battery is for.
- Edit any watts or hours field to match the label on your own gear — the defaults are typical values, not your household.
- Once the load list keeps landing on “stack 2+”, that’s usually a sign the real fix is a designed, installed system, not a bigger box.
Want the full walkthrough first? Read how big a power station you actually need.