Most deep-well pumps run on 240 volts. Most power stations put out only 120 volts, and a 120V station cannot turn a 240V pump at all, however big its battery. So check your pump’s voltage first. It is on the nameplate in the pressure switch box or control box, or in your well driller’s report.
- 230V or 240V: you need one of the two 240V units below.
- 115V or 120V: one of the two 120V units can work, if its surge covers your pump’s start.
Then size for the start, not the run. A pump pulls several times its running power for a moment as it kicks on. Each pick says which pumps its surge covers on paper, using Franklin Electric’s motor data.
Sizing: Why You Buy for the Surge, Not the Run
A pump motor pulls a big spike of current the instant it starts, far more than it draws while running. If a station cannot cover that spike, it trips the moment the pump kicks on, even if it looked big enough on paper. So you size for the start.
The number to find is the pump’s locked-rotor amps (LRA). It is printed on the motor or control-box label, or in the pump manual. LRA times the motor’s rated voltage gives its worst-case starting demand. For reference, Franklin Electric’s motor data for common 4-inch submersible motors:
- 1/2 HP: about 960 watts at maximum load. It starts at about 5,300 VA (230V 3-wire), 5,800 VA (115V 3-wire) or 7,400 VA (2-wire, either voltage).
- 3/4 HP (230V): about 1,310 watts at maximum load. It starts at about 7,900 VA (3-wire) or 9,400 VA (2-wire).
- 1 HP (230V): about 1,600 watts at maximum load. It starts at about 9,600 VA (3-wire) or 11,200 VA (2-wire).
- 1.5 HP (230V): about 2,100 to 2,300 watts at maximum load. It starts at about 11,800 VA (3-wire) or 15,200 VA (2-wire).
Two-wire pumps have their starting parts inside the motor and no control box, so they are harder to start than three-wire pumps. Real starting draw falls when the voltage dips, so a station rated a bit below these figures may still start some pumps. But makers rarely say how long their surge rating lasts.
To get your own pump’s number, read its start with an inrush clamp meter on the pump circuit, or have an electrician do it.
The practical takeaway: compare your pump’s LRA times its voltage with the station’s surge rating. Then give the station’s maker your pump’s voltage, horsepower, LRA and whether it is 2-wire or 3-wire, and ask whether their unit will start it. Soft-start pumps such as Grundfos SQ models, and constant-pressure drives such as Franklin’s SubDrive, reduce the starting surge; both need a qualified installer. If your pump has neither, an add-on soft starter can lower its start. A small power station will run your lights and fridge but will usually stall a well pump.
EcoFlow DELTA Pro 3
If your 240V pump is 1/2 HP, or a 3/4 HP 3-wire, the DELTA Pro 3 is the lightest way here to get 240V from one box. It has an L14-30 outlet (120V/240V) and a NEMA 6-20 outlet (240V), so it needs no hub and no second unit. Its 8000-watt surge covers Franklin’s start figures for a 1/2 HP 240V pump and a 3/4 HP 3-wire on paper.
EcoFlow says it can power a 1 HP water pump, but it does not say what kind. Franklin’s 1 HP submersible starts at about 9,600 VA or more, above its 8,000W surge on paper, so give EcoFlow your pump’s LRA before you buy. Skip it if your pump is a 3/4 HP 2-wire, or 1 HP or larger, with no soft start.
The battery is 4096Wh with 4000 watts continuous. It expands to 12kWh per unit with extra batteries and recharges from solar during the day. The downsides are weight and how the outlets switch. At about 114 pounds it needs a fixed spot near the pump circuit, and its 120V outlets turn off while its 240V outlets are on.
Anker SOLIX F3800 Plus
The SOLIX F3800 Plus is the current version of Anker’s F3800. It gives 240V from one unit through an L14-30 outlet, and Anker lists 6000 watts of output, the most of any pick here. That is room to run the pump with a fridge and lights, as long as their starts do not overlap.
The catch is the start. Anker’s page lists no surge rating for the Plus, so you cannot check it against your pump on paper. Before you buy, give Anker your pump’s voltage, horsepower, LRA and whether it is 2-wire or 3-wire, and ask them to confirm it will start. Skip it if you want a published surge figure to compare; the DELTA Pro 3 lists one.
The battery is 3840Wh and expands to about 27kWh with extra batteries. It takes up to 3200 watts of solar. Anker notes that the 240V output cannot be used while the unit is charging from 120V AC. The trade-off is size: at about 137 pounds it is bulky and wants a dedicated spot.
EcoFlow DELTA Pro (Original)
The original DELTA Pro is for a 120V pump. Its 7200-watt surge covers Franklin’s 1/2 HP 115V 3-wire start, about 5,800 VA, with room on paper. A 2-wire, about 7,400 VA, is just above it. Its 3600Wh battery runs more fill-the-tank cycles than the DELTA 3 Max Plus. Check your pump’s locked-rotor amps first, and skip it if your pump is 240V: one unit has no 240V outlet.
It is also an on-ramp to 240V. Two DELTA Pros bonded through EcoFlow’s Double Voltage Hub give 240 volts, so you can start with one unit for general backup and add the second unit plus the hub later. Each unit expands to about 10.8kWh with two extra batteries.
Be clear about the 240V part, though. That path means two large DELTA Pros plus the hub, at about 99 pounds each. If your only goal is to run a 240V well today, the DELTA Pro 3 or SOLIX F3800 Plus is the simpler route.
EcoFlow DELTA 3 Max Plus
The DELTA 3 Max Plus is the lighter 120V pick, for a 1/2 HP pump. Its 6000-watt surge covers Franklin’s 1/2 HP 115V 3-wire start, about 5,800 VA, on paper, per EcoFlow’s specs. A 2-wire, about 7,400 VA, is above both 120V stations here on paper, so add the soft starter below or ask the maker. For a jet pump or a bigger 120V pump, check its LRA times its nameplate voltage against the DELTA Pro’s 7,200W.
At about 49 pounds it weighs about half as much as the DELTA Pro. The trade-off is a 2048Wh battery, also about half the DELTA Pro’s, so plan on short fill-the-tank runs. It has 120V outlets only, so skip it if your pump is 240V.
If Your Pump’s Start Is Too Big for One Unit
If your pump’s start is above the surge of the station you want, a soft starter can lower it. The maker’s sizing sheet works its example at about a 40% cut in starting current, which may let a smaller station start the pump.
Connecting a Station to Your Well
A licensed electrician installs an inlet box and a transfer switch or interlock that matches your station’s 240V outlet, which is listed on each card above. Never backfeed a wall outlet. Backfeeding can electrocute line workers and start fires.
What We Looked For
- Voltage match. Whether a unit can run a 240V pump at all. Each card names its 240V outlet, or says it is 120V only.
- Surge. Each pick’s surge is checked against Franklin Electric’s start figures. The EcoFlow picks list 6,000 watts of surge or more; Anker lists none for the F3800 Plus, so ask Anker. No surge rating guarantees a pump will start.
- Battery and expansion. A bigger battery means more fill-the-tank cycles in a long outage. Each unit expands and recharges from solar.
- Weight and setup. These units live in one spot near the pump circuit, and an electrician connects them.
Before You Buy
A solar generator is one piece of a well backup plan. The strategy around it matters as much as the unit:
- Well pump backup power. Generators, hand pumps, stored water, and the fill-then-shut-off trick.
- What size power station do I need. How to add up running and surge watts for your whole setup.
- Best portable power stations. The general backup roundup for fridges, lights, and smaller loads.
Frequently Asked Questions
Bottom Line
If your 240V pump is 1/2 HP or a 3/4 HP 3-wire, the EcoFlow DELTA Pro 3 is the lightest way to get 240V from one box. For a 3/4 HP 2-wire, or any pump 1 HP and up, it does not cover the start on paper. The Anker SOLIX F3800 Plus gives the most running power, but Anker lists no surge rating for it, so have Anker confirm it will start your pump.
For a 1/2 HP 115V 3-wire pump, the EcoFlow DELTA Pro gives you the bigger battery and the EcoFlow DELTA 3 Max Plus the lighter box. If your pump starts above the station you want, look at the soft starter or ask the station maker. Whatever you buy, confirm your pump’s voltage off the nameplate first. That tells you which group of picks fits. Then match the surge to your pump’s start.
