What Size Solar Panel Do I Need for a Sump Pump?

500W running draw1500W surge24h/day defaultwater

Quick Answer

A Sump Pump at 500W needs at least 800W of solar panels to run sustainably. The compressor cycles about 20% of the time, so actual daily consumption is 2.4 kWh. You need 800W of solar total (4 panels at 200W each). Pair with a 600Ah LiFePO4 battery at 12V for 2-day cloudy weather reserve. The EcoFlow Delta 2 is the simplest all-in-one solution for this load. The 1,500W startup surge means your inverter must be rated at least 2000W continuous.

System Specs for a Sump Pump

Calculated for 24 hours/day usage, 5 peak sun hours, and 2-day LiFePO4 battery autonomy. Duty cycle of 20% applied (the sump pump cycles on/off).

ComponentMinimum SizeDetails
Daily Energy2.4 kWh500W at 20% duty cycle for 24h
Solar Panels800W4x 200W or 8x 100W panels
Battery600Ah at 12VLiFePO4, 2-day reserve (7.2 kWh usable)
Charge Controller90A MPPTHandles up to 800W panel input at 12V
Inverter1000W continuousMust handle 1,500W startup surge, pure sine wave required

Running more than just a sump pump? Add more appliances to your load with our full calculator

Recommended Power Station

EcoFlow Delta 2

2,048Wh capacity, 1,800W AC output — handles a fridge, TV, microwave, and most RV loads.

2,048Wh

Capacity

1,800W

AC Output

500W

Max Solar In

Buy on EcoFlow.comView with Solar Panel Bundle

DIY Component List

Building your own system for a sump pump? These components match the specs above.

Solar Panel

800W total

Renogy 400W Solar Starter Kit (2x200W + MPPT) on Amazon

Battery

600Ah 12V LiFePO4 minimum

LiTime 12V 200Ah LiFePO4 on Amazon

Charge Controller

90A MPPT minimum

Renogy 40A MPPT Rover on Amazon

Inverter

1000W pure sine wave, 2500W surge

Renogy 2000W Pure Sine Wave Inverter on Amazon

About the Sump Pump Solar Load

A sump pump draws 300–800 watts when running with startup surges up to 1,500 watts, averaging 500 watts. It cycles intermittently — perhaps 12 minutes per hour during heavy rain, giving a 20% duty cycle. True daily consumption varies from 200–500Wh under normal conditions. The 24-hour monitoring period matters because the pump must respond to rain at any hour.

Frequently Asked Questions

How do I power a sump pump with solar for emergencies?▼
A sump pump backup solar system needs to operate autonomously during grid outages, often during the same storm that causes flooding. You need 2 days of autonomy minimum — enough battery to run the pump 200–500Wh per day for 48 hours without sun. That means a 200Ah LiFePO4 battery at 12V (2,400Wh usable) plus a 200–400W solar array to recharge between outages. The inverter must handle 1,500W surge. EcoFlow Delta 2 Max with a 220W panel is the ready-made emergency backup for sump pump protection.
Will a battery backup sump pump work better than a solar system?▼
Traditional battery backup sump pumps (12V DC, separate from your main pump) are simpler and purpose-built for this application. Units from Wayne, Basement Watchdog, and Liberty draw directly from a dedicated 12V AGM battery charged from AC when grid power is available. These cost $150–300 all-in and are the right answer for a primary sump backup. A solar system makes sense if you want a versatile whole-home backup that handles the sump pump plus lights, refrigerator, and other critical loads simultaneously.
What happens to a sump pump during a power outage without backup?▼
Without backup power, your sump pump stops during the grid outage — which often coincides exactly with heavy rain events. Water accumulates in the sump pit and floods the basement when the pit overflows. Foundation damage, mold, and ruined property follow. This is why emergency backup power for a sump pump is worth prioritizing. A 200Ah LiFePO4 battery bank runs a 500W sump pump at 20% duty cycle for over 20 hours — enough to cover almost any storm event.

Related Water Appliances

Well Pump (1 HP)

750W at 25% duty cycle

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