What Size Solar Panel Do I Need for a Well Pump (1 HP)?

750W running draw2250W surge1h/day defaultwater

Quick Answer

A Well Pump (1 HP) at 750W needs at least 100W of solar panels to run sustainably. The compressor cycles about 25% of the time, so actual daily consumption is 188 Wh. A single 100W solar panel covers it. Pair with a 50Ah LiFePO4 battery at 12V for 2-day cloudy weather reserve. The EcoFlow River 2 is the simplest all-in-one solution for this load. The 2,250W startup surge means your inverter must be rated at least 3000W continuous.

System Specs for a Well Pump (1 HP)

Calculated for 1 hours/day usage, 5 peak sun hours, and 2-day LiFePO4 battery autonomy. Duty cycle of 25% applied (the well pump (1 hp) cycles on/off).

ComponentMinimum SizeDetails
Daily Energy188 Wh750W at 25% duty cycle for 1h
Solar Panels100W1x 100W panel covers it
Battery50Ah at 12VLiFePO4, 2-day reserve (565 Wh usable)
Charge Controller20A MPPTHandles up to 100W panel input at 12V
Inverter1000W continuousMust handle 2,250W startup surge, pure sine wave required

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Recommended Power Station

EcoFlow River 2

256Wh capacity, 300W AC output — ideal for phones, laptops, CPAP, and small electronics.

256Wh

Capacity

300W

AC Output

110W

Max Solar In

Buy on EcoFlow.comView with Solar Panel Bundle

DIY Component List

Building your own system for a well pump (1 hp)? These components match the specs above.

Solar Panel

100W total

Renogy 200W 12V Monocrystalline on Amazon

Battery

50Ah 12V LiFePO4 minimum

LiTime 12V 100Ah LiFePO4 on Amazon

Charge Controller

20A MPPT minimum

Renogy 40A MPPT Rover on Amazon

Inverter

1000W pure sine wave, 3500W surge

Renogy 2000W Pure Sine Wave Inverter on Amazon

About the Well Pump (1 HP) Solar Load

A 1-horsepower well pump draws about 750 watts while running with a 2,250-watt startup surge. Pumps only run a fraction of the time — roughly 15 minutes per hour of actual use time, giving a 25% duty cycle. Daily consumption for a household depends on water usage but typically runs 750–1,500Wh. The surge current is the critical design constraint: it requires a large inverter and a battery bank with very low internal resistance.

Frequently Asked Questions

What size solar system do I need for a well pump?▼
A 1HP well pump at 750W running 2 hours per day consumes 1,500Wh daily. The surge to start the pump motor hits 2,250 watts. You need a 2,500W pure sine wave inverter minimum, a 24V or 48V battery bank of at least 200Ah LiFePO4 to handle surge current cleanly, and roughly 600–800W of solar panels. The EcoFlow Delta 2 Max (2,400W output) handles a 1HP pump, making it the simplest turnkey option. For a DIY system, an Aims 3,000W pure sine inverter paired with two 100Ah 24V LiFePO4 batteries and four 200W panels is a reliable well pump system.
Can a well pump run directly on solar without batteries?▼
DC solar pumps designed for direct-solar operation exist and are popular for livestock watering and irrigation. Brands like Grundfos, Shurflo, and Franklin Electric make submersible pumps that operate on variable DC voltage directly from solar panels. These pumps slow down as sun decreases and stop at night, which works for filling a tank during the day rather than on-demand pressure. For a residential well with pressure-on-demand operation, you need a battery bank and inverter. Direct DC pumping is only practical for dedicated irrigation or livestock water tank applications.
Why does a well pump trip inverters on startup?▼
Well pumps use induction motors that draw 3x their running current for the first 1–2 seconds during startup. A 750W pump pulling 2,250W surge will trip a 2,000W inverter's overload protection. The solution is to oversize the inverter: buy a 3,000W continuous rated unit so the 2,250W surge is well within its surge capacity rating. Undersized inverters trip on every pump start, eventually damaging both the inverter and the pump motor. LiFePO4 batteries also handle surge current far better than AGM — a 100Ah LiFePO4 can deliver 200A peak for a second; a comparable AGM cannot.

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