Battery backup for your sump pump in Illinois

Heavy rain and power outages tend to arrive together. In the July 2, 2023 storms, the National Weather Service reported that a few spots west of Chicago got more than 8 inches of rain, and more than 8,000 Chicagoans called the city to report flooded basements, with more than 3,400 damage reports in suburban Cook County. Wind storms knock out power on the same summer afternoons: ComEd said about 684,000 customers lost power in the June 2026 storms, and more than 430,000 in the July 15, 2024 storms.

The Metropolitan Water Reclamation District lists malfunctioning sump pumps as a common source of basement water and tells homeowners to check that theirs is working. A pump that has no power is the same as a broken one.

Even running nonstop, a 720-watt pump would use about 7.2 kWh in 10 hours, roughly half of one 13.5 kWh battery. Real pumps cycle on and off as the pit fills, so most use far less. Starting current is the bigger question, and a sump pump's is modest: Tesla rates Powerwall 3 to start loads up to 185 amps for one second.

They solve different problems, so a home with a finished basement may want both: the backup pump covers a stuck float or burned-out motor, and the home battery keeps the main pump and the rest of the house going through a long outage. See what a home battery costs in Illinois.

No. Standard grid-tied solar shuts off when the grid goes down, so line workers aren't hurt by power flowing back onto the lines. You need a battery and a backup panel for solar to keep anything running. With a battery, solar becomes valuable in a multi-day outage, because it refills the battery each day. See does solar work in a power outage.

Any of the major home batteries can run a typical sump pump. The differences show up when the pump starts at the same moment as other big loads:

• Tesla Powerwall 3: 11.5 kW continuous and up to 185 amps of starting current for one second.
• Enphase IQ Battery 5P: 3.84 kVA continuous per battery, with 7.68 kW peak for 3 seconds. Many homes stack two or more.
• FranklinWH aPower 2: 10 kW continuous and 15 kW peak for 10 seconds.

Put the sump pump on the backup panel along with the refrigerator and furnace, and keep central air off it unless you have two or more batteries. See Powerwall 3 vs. Enphase vs. FranklinWH and whole-home vs. essentials backup.

Usually not on a standard policy. NerdWallet notes that water backing up through sewers or overflowing a sump pump is typically excluded unless you add a water backup endorsement, and that coverage has its own limit. Check your policy before storm season, and see solar and homeowners insurance in Illinois.

1. 1

   Is the sump pump on the backup panel?

   Make sure it's on the list of backed-up circuits, along with any ejector pump.

2. 2

   Will the battery start it with other loads running?

   Give them the pump's horsepower and starting amps from its label.

3. 3

   How long will backup last in a storm?

   Ask for an estimate with and without solar recharging.

4. 4

   Should I keep a backup pump too?

   Ask whether a second pump in the pit makes sense for your basement.

Comparing with a generator? See standby generator vs. battery.