Usually the question is surge (locked-rotor amps), not kilowatt-hours. We do not have a pump dyno. We can only compare published inverter numbers to typical pump nameplates. For the hour-by-hour sequence after the grid drops, see what dies first in a multi-day outage.
Decision gate (new 27 Sep 2026)
Nameplate LRA → soft-start yes/no → which inverter class. This page keeps the product cards. The decision sequence lives on the soft-start guide.
Soft-start + battery decision gate How to connect Inlet & interlockBasement sump pump instead? That is usually a 120 V pump that cycles on and off, a different job: sump pump battery backup.
A ½ hp 240 V well pump often draws ~800–1,200 W running and several times that for a moment at start. A 1 hp pump is worse. Soft-start kits can cut start current when the motor path is compatible — see the soft-start decision gate. They are a better spend than a random 2 kW “solar generator,” and still not a well-pump guarantee.
Read your pump’s LRA on the badge. If the seller cannot tell you LRA or surge, do not take their “runs a well pump” claim.
More continuous watts than Delta Pro 3. Still not a published LRA figure. Soft-start the pump first.
Serious running-watt headroom. Still confirm your pump’s LRA against the kit you actually order.
Manufacturer surge marketing up to 45 kW. Promising on paper; we have not logged a start.
Surge is the hard part. Size the job, then check runtime and fuel-vs-battery for multi-day outages.
Find my backup Runtime calculator 2026 rankings Generator vs battery