A well pump is one of the harder household loads to back up because voltage and motor startup matter as much as battery size. Many residential pumps are 240V, and startup demand can be several times running watts. Start with the pump nameplate whenever possible.
Enter your well-pump watts, voltage and outage plan in the Backup Power Map →
What size backup power does a well pump need?
Published manufacturer guidance puts residential well pumps across a wide range, roughly 500–2,000W while running depending on pump type, horsepower and well depth. Motor startup can be much higher. That means a battery with enough watt-hours can still fail if its inverter cannot supply the required voltage or startup current.
120V vs 240V changes the answer
Check the pump nameplate before buying. If your pump is 208/230/240V, a normal 120V portable power station is not a direct fit. You need a system specifically configured for 120/240V service and compatible connection hardware.
Examples by pump size
For screening only, a 1/2 HP pump may be around the 1kW running class with several kilowatts of startup demand; larger 1 HP and 1.5 HP pumps can require substantially more. Actual installation values override estimates.
Battery capacity and runtime
Well pumps usually cycle rather than run continuously. Estimate daily watt-hours from actual running watts × total run time per day. Then add inverter losses and reserve. The WhenGridFails calculator does this while also checking startup and voltage.
What should you buy?
For a 120V pump, compare verified continuous output and motor-start capability first. For a 240V pump, start with 120/240V-capable systems such as the BLUETTI Apex 300 class, then verify the required hub, transfer equipment and your pump’s nameplate.
Check BLUETTI Apex 300 price & availability →
Affiliate disclosure: WhenGridFails may earn a commission at no extra cost to you. Technical load fit comes first. Hardwired pump connections and transfer equipment should be reviewed by a qualified electrician.
Decision checklist
Confirm voltage, running watts or amps, startup demand, desired gallons/pressure-tank cycling during the outage, outage duration, recharge method and connection method. Do not select a system from horsepower alone.