Yes — and you should plan it before the storm does it for you: outages and flooded basements arrive together. Put in your pump and your storm pattern, and get Wh per storm day, the surge your inverter must clear, and the battery that outlasts the outage.
Loading regional defaults…
W
/h
s
hours
PUMP RUNTIME
0 min over the outage
ENERGY NEEDED
0 Wh
START-UP SURGE
0 W inverter must clear this
BATTERY (USABLE)
0 Wh with 25% storm margin
Matched power station tier: —
How this is calculated
A sump pump is a burst load: runtime over the outage is cycles per hour × seconds per cycle × hours. At the defaults (6 cycles of 25 seconds, 24 hours) the pump actually runs just one hour — about 800 Wh for a ⅓ HP pump. The battery figure adds a 25% margin, because the storm that takes the grid down is rarely the storm you measured on.
The number that disqualifies cheap hardware is the surge: an across-the-line pump motor kicks at roughly 2.5× running watts — 2,000W for a ⅓ HP pump — and it does so dozens of times a day, so the inverter needs that as repeatable headroom, not a one-off peak rating.
Solar deserves honesty here: the pump works hardest exactly when the sky produces least. Panels refill the battery between weather systems; the battery alone carries the outage. Size the battery for the storm and treat the panel as the recovery plan.
Count your real cycles: tape a night’s storm on your phone, or count float trips for ten minutes of heavy rain and multiply.
Check the pit and check valve before upsizing the battery — a leaking check valve doubles cycle counts for free.
On municipal water, a water-powered backup ejector is the zero-electricity belt to the battery’s braces; on a well, the battery is the plan.
~800W at ⅓ HP, ~1,050W at ½ HP, ~1,500W at ¾ HP while running — with a 2–3× start-up surge each cycle.
How long will a 2 kWh battery run one?
About two heavy-storm days at typical cycling — the constraint is the inverter clearing the 2,000W+ surge, not the energy.
Why not just solar panels?
Storms and solar don’t overlap. The battery carries the outage; panels refill it when the sky clears.
What we’d actually buy
Storm math done — this is the hardware that keeps the pit dry when the grid is the thing that failed. Picked on merit from what’s on the market right now — street prices, checked July 2026.
Zoeller Aquanot 508 — 40 GPM standalone backup that bolts beside the primary you already own. $430–480
Wayne ESP25 — the budget backup — up to 10,000 gallons on one 75Ah charge, cast-iron housing. $320–360
Deep-cycle AGM, group 27/31 — the consumable every backup pump runs on — plan on replacing it every 3–5 years. $180–260
Chosen on merit — nobody paid to be on this list, and several of these can never earn us a penny. If a link here ever earns Grid CEO a referral fee, it will say so — disclosure.
Grundfos Unilift KP 250 — the cellar-drainage standard — pair it with a battery station for outage cover. €250–350
EcoFlow DELTA 3 Plus — 1kWh with UPS-grade switchover — keeps a sump alive through the outages that matter. €700–850
Chosen on merit — nobody paid to be on this list, and several of these can never earn us a penny. If a link here ever earns Grid CEO a referral fee, it will say so — disclosure.
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