Refrigerator and Well Pump Solar Sizing Guide (24, 48 and 72 Hours)
A full-size refrigerator needs about 1,500Wh of battery per day with a safety margin, and 400W of solar panels keeps it running indefinitely in good sun.
Adding one 240V well pump (about an hour of pumping a day) raises the daily need to about 2,750Wh, and two pumps to about 4,000Wh.
How to use this guide:
- Estimate your daily watt-hours (Wh).
- Decide how many days you want to run without power from the grid.
- Choose a battery and solar panels to match, using the tables below.
New to solar generators? Start with our How to Choose a Solar Generator guide.
Quick Answer: How Much Battery Do You Need?
This is the battery size needed to run the load with no sun at all. Each figure includes a 20% margin for inverter losses and standby draw.
Quick Answer: How Much Battery Do You Need?
This is the battery size needed to run the load with no sun at all. Each figure includes a 20% margin for inverter losses and standby draw.
| What you want to run | Daily use (Wh) | 24 hours | 48 hours | 72 hours |
|---|---|---|---|---|
| One refrigerator | 1,200 | 1,500Wh | 3,000Wh | 4,500Wh |
| Refrigerator + one 240V well pump | 2,200 | 2,750Wh | 5,500Wh | 8,250Wh |
| Refrigerator + two 240V well pumps | 3,200 | 4,000Wh | 8,000Wh | 12,000Wh |
These are planning estimates for a typical full-size refrigerator and a ½ HP well pump that runs about an hour a day. Your numbers will differ, and the next section shows how to check them.
Add solar panels and the battery can be much smaller, because the sun refills it every day.
How We Calculated This
Every figure on this page comes from four inputs. Swap in your own numbers and the same formulas work.
1. Refrigerator: 1,200Wh per day.
A refrigerator cycles on and off, so its daily energy matters more than its running watts.
The yellow EnergyGuide label inside the fridge lists estimated yearly kWh. Divide by 365 and multiply by 1,000 to get Wh per day. Example: 450 kWh a year is about 1,233Wh a day.
A plug-in watt meter gives a measured number if the label is missing.
Many full-size refrigerators use roughly 1,000 to 1,400Wh a day, depending on age, size, room temperature and how often the door is opened. Older or very large models can use more. We use 1,200Wh as a planning figure.
2. Well pump: about 1,000Wh per hour of pumping.
Typical 240V pump draw, with startup power commonly 2 to 3 times the running watts:
| Pump size | Running watts | Startup surge (2–3×) |
|---|---|---|
| ½ HP | about 960W | about 1,900–2,900W |
| ¾ HP | about 1,320W | about 2,600–4,000W |
| 1 HP | about 1,920W | about 3,800–5,800W |
The 1,000Wh figure is the energy for one hour of the pump actually running (about 960W for a ½ HP pump). Our tables assume one hour of running time per day for each pump, so a pump that runs more or less than that changes the total.
Our tables use a ½ HP pump. For a ¾ HP or 1 HP pump, multiply the pump portion by 1.4 or 2. Check the pump nameplate for volts and amps, since watts = volts × amps.
3. Pumping hours: we plan on one hour a day per pump.
To estimate yours: gallons used per day ÷ gallons per minute your pump delivers ÷ 60.
One hour a day is a cautious planning figure, and a small pressure tank makes the pump start more often. If you are unsure, ask your well installer for the pump's flow rate and your tank size.
4. Real-world margin: divide by 0.8.
Inverter losses and the unit's own standby draw mean you never get 100% of the rated watt-hours.
The formulas:
- Battery needed (Wh) = daily Wh × days ÷ 0.8
- Panels needed (W) = daily Wh ÷ (0.75 × peak sun hours)
- Days to recharge = battery Wh ÷ (panel W × 0.75 × peak sun hours)
The 0.75 allows for heat, wiring and angle losses. "Peak sun hours" is the number of hours per day the sun delivers full-strength light. We use 5 for a good sunny day and 3 for cloudy weather, winter, or northern locations.
Solar Panels Needed to Keep It Running Day After Day
With enough panels, the sun replaces what you use each day and the battery only has to carry you through nights and cloudy stretches. This is how many watts of panels cover each load.
| What you want to run | Daily use (Wh) | Panels in good sun (5 sun hours) | Panels in weak sun (3 sun hours) |
|---|---|---|---|
| One refrigerator | 1,200 | 320W, plan on 400W | 533W, plan on 600W |
| Refrigerator + one 240V well pump | 2,200 | 587W, plan on 600W | 978W, plan on 1,000W |
| Refrigerator + two 240V well pumps | 3,200 | 853W, plan on 1,000W | 1,422W, plan on 1,500W |
Pair the panels with at least one day of battery from the Quick Answer table (1,500Wh, 2,750Wh or 4,000Wh) so nights and cloudy days are covered. The panels run your loads first and send the leftover to the battery.
In the northern U.S. and the Pacific Northwest, December sun can drop to 1 to 2 peak sun hours, so the weak-sun column may not be low enough. See the low-sun section of our How to Choose a Solar Generator guide before you size panels.
Two things can cap how many panels a power station will use: its maximum solar input in watts, and its maximum input voltage. Panels wired in series add voltage, and exceeding the limit can damage the charge controller.
The product section lists each unit's limits, and our Solar Panel Guide explains series and parallel wiring.
How Long Solar Takes to Recharge the Battery
This table shows days of sun to refill an empty battery. Each cell reads "good sun (5 sun hours) / weak sun (3 sun hours)".
| Battery size | 400W of panels | 800W of panels | 1,600W of panels | 2,400W of panels |
|---|---|---|---|---|
| 2,000Wh | 1.3 / 2.2 days | 0.7 / 1.1 days | 0.3 / 0.6 days | 0.2 / 0.4 days |
| 4,000Wh | 2.7 / 4.4 days | 1.3 / 2.2 days | 0.7 / 1.1 days | 0.4 / 0.7 days |
| 8,000Wh | 5.3 / 8.9 days | 2.7 / 4.4 days | 1.3 / 2.2 days | 0.9 / 1.5 days |
| 12,000Wh | 8.0 / 13.3 days | 4.0 / 6.7 days | 2.0 / 3.3 days | 1.3 / 2.2 days |
The table assumes an empty battery and nothing else running. Once your refrigerator and pump are running, only the leftover solar refills the battery.
Example: 800W of panels in good sun makes about 3,000Wh a day. A refrigerator and one well pump use 2,200Wh of that, leaving about 800Wh a day to refill the battery. A 4,000Wh battery would take around five days to refill.
To refill faster, add panels. The formula is: panels needed (W) = (daily use + battery Wh ÷ days to refill) ÷ (0.75 × sun hours).
To refill a 4,000Wh battery in 2 days while running a refrigerator and one well pump, that is (2,200 + 2,000) ÷ 3.75, or about 1,120W. Plan on 1,200W.
Running a Well Pump: What Changes
Important: Never power a hard-wired well pump or your house by plugging a power station into a wall outlet with a double-male cord.
It can send power back into the utility lines and endanger line workers, and it violates electrical codes. Have a licensed electrician install a transfer switch, interlock kit or home panel.
A refrigerator is easy. A well pump is the hard load, for four reasons.
Voltage. Many well pumps run on 240V. Check the pump's nameplate or your pressure switch. If it says 240V, you need a power station with a 240V output (listed in the product section). A 120V-only unit cannot run it.
Startup surge. A pump motor draws 2 to 3 times its running watts for a moment when it starts. A ½ HP pump can briefly pull up to about 2,900W, and a 1 HP pump up to about 5,800W.
The power station's surge rating must cover that plus anything else already running.
Two pumps. If both run at once, add their running watts. If one is running when the other starts, add the second pump's startup surge to the first pump's running watts.
Two ½ HP pumps can briefly reach about 3,900W. Plan on a 4,000W or larger unit, and ask us before relying on one that is close to that number.
Starts per day. A small pressure tank makes the pump start about 10 times a day, versus about 3 for a large tank. Fewer starts means fewer surges. Your well installer can tell you your tank size.
The connection must be done by a licensed electrician. Most well pumps are hard-wired to your home's electrical panel, so you cannot simply plug one into a power station.
The safe options are a transfer switch, an interlock kit, or a smart home panel, installed to your local code.
Never connect a power station to a wall outlet with a double-male cord. It can send power back into the utility lines and endanger line workers.
Our Solar Generators, GFCI & AFCI Protection Guide covers the protection details.
Ask your electrician or well installer whether a soft-start device suits your pump. It can reduce the startup surge, which may let a smaller power station do the job.
Your installer should decide, not a spec sheet.
Conserving water during an outage lowers pumping hours and stretches your battery.
Power Stations That Fit: EcoFlow, Jackery, BLUETTI and Anker
There are two groups. For a refrigerator alone, a 2,000Wh-class unit with standard 120V outlets works. For a well pump, you need a unit with a 240V output.
For one refrigerator (120V, about 2,000Wh)
| Unit | Capacity | AC output | Max solar input | Notes |
|---|---|---|---|---|
| Anker SOLIX C2000 Gen 2 | 2,048Wh | 2,400W (4,000W peak) | 800W | Expands with BP2000 batteries (2,048Wh each) |
| Anker SOLIX F2600 | 2,560Wh | 2,400W (2,800W surge) | 1,000W | Expands with BP2600 batteries (2,560Wh each) |
| BLUETTI Apex 300 | 2,764.8Wh | 3,840W continuous AC output, 7,680W surge output | 2 × 1,200W, 12-60VDC, 2 × 20A | 5-year warranty |
| EcoFlow DELTA 3 Max Plus | 2,048Wh | 3,000W (6,000W surge) | 1,000W | Expands to 10kWh with extra batteries |
| Jackery Explorer 2000 v2 | 2,042Wh | 2,200W (4,400W surge) | about 400W | Not expandable |
For a well pump (120V/240V)
| Unit | Built-in capacity | AC output | Max solar input | Expansion |
|---|---|---|---|---|
| Anker SOLIX F3000 | 3,072Wh | 3,600W on 120V (7,200W surge), plus a 240V L14-30 outlet | 2,400W (1,600W high-voltage + 800W low-voltage ports) | BP3000 expansion battery (3,072Wh); ask us to confirm the pairing |
| Anker SOLIX F3800 Plus | 3,840Wh | 6,000W on the 120V/240V port | 3,200W (two 1,600W inputs) | BP3800 batteries, 3,840Wh each, up to 6 (26.9kWh total) |
| BLUETTI Apex 300 | 2,764.8Wh | 3,840W (7,680W lifting power) | up to 4,000W with the SolarX 4K | B300K batteries; the Apex 300 + B300K bundle is 5,529.6Wh |
| EcoFlow DELTA Pro | 3600Wh | 3600Wh (8,000W surge, 6,000W with X-Boost) | 2,600W (1,600W + 1,000W inputs) | Up to two extra batteries |
| Jackery Explorer 5000 Plus | 5,040Wh | 7,200W (14,400W surge) | 1,200W on the low-voltage inputs, plus a high-voltage input (135–450V) | Battery Pack 5000 Plus, 5,040Wh each, up to 5 (30kWh total) |
Which unit reaches each battery target with no sun. Each cell is the smallest configuration from the tables above that meets the target. Capacity in Wh is in parentheses. Targets come from the Quick Answer table.
| Goal (battery needed) | Anker | BLUETTI | EcoFlow | Jackery |
|---|---|---|---|---|
| Fridge, 24 hours (1,500Wh) | C2000 Gen 2 (2,048) | Elite 200 V2 (2,074) | DELTA 3 Max Plus (2,048) | Explorer 2000 v2 (2,042) |
| Fridge, 48 hours (3,000Wh) | F3000 (3,072) | Apex 300 + B300K (5,530) | DELTA Pro 3 (4,096) | Explorer 5000 Plus (5,040) |
| Fridge, 72 hours (4,500Wh) | F2600 + BP2600 (5,120) | Apex 300 + B300K (5,530) | DELTA Pro 3 + 1 extra battery (8,192) | Explorer 5000 Plus (5,040) |
| Fridge + 1 well, 24 hours (2,750Wh) | F3000 (3,072) | Apex 300 (2,765) | DELTA Pro 3 (4,096) | Explorer 5000 Plus (5,040) |
| Fridge + 1 well, 48 hours (5,500Wh) | F3800 Plus + BP3800 (7,680) | Apex 300 + B300K (5,530) | DELTA Pro 3 + 1 extra battery (8,192) | Explorer 5000 Plus + 1 pack (10,080) |
| Fridge + 1 well, 72 hours (8,250Wh) | F3800 Plus + 2 BP3800 (11,520) | Apex 300 + 2 B300K (8,294) | DELTA Pro 3 + 1 extra battery (8,192)* | Explorer 5000 Plus + 1 pack (10,080) |
| Fridge + 2 wells, 24 hours (4,000Wh) | F3800 Plus + BP3800 (7,680) | Apex 300 + B300K (5,530) | DELTA Pro 3 (4,096) | Explorer 5000 Plus (5,040) |
| Fridge + 2 wells, 48 hours (8,000Wh) | F3800 Plus + 2 BP3800 (11,520) | Apex 300 + 2 B300K (8,294) | DELTA Pro 3 + 1 extra battery (8,192) | Explorer 5000 Plus + 1 pack (10,080) |
| Fridge + 2 wells, 72 hours (12,000Wh) | F3800 Plus + 3 BP3800 (15,360) | Apex 300 + 4 B300K (13,824) | DELTA Pro 3 + 2 extra batteries (12,288) | Explorer 5000 Plus + 2 packs (15,120) |
*Within 1% of the target. The 20% margin already built into the target covers the gap, and any solar closes it.
Solar shrinks every row. With enough panels the battery only has to cover nights and cloudy days, so one day of battery plus the panel size from the solar table is often enough.
For example, a refrigerator and one well pump can run on an F3800 Plus or DELTA Pro 3 with about 600W to 1,000W of panels, depending on how much sun you get.
Check the solar input limit before you buy panels. A 2,400W array only helps if the power station accepts that much.
The 2,000Wh-class units above accept 400W to 1,000W, so they refill slowly.
The Anker F3800 Plus, EcoFlow DELTA Pro 3 and BLUETTI Apex 300 accept 2,600W to 4,000W.
The Jackery Explorer 5000 Plus accepts 1,200W on its low-voltage inputs plus its high-voltage input, so ask us how much of your array it can use.
Expansion batteries and bundles change, so we confirm the exact configuration with you before you order. Browse EcoFlow, Jackery and BLUETTI, or ask us about Anker SOLIX.
Other Ways to Recharge When the Sun Is Weak
Solar is the free option, but a good plan has a second way to refill. Use whichever of these fits your setup.
- Wall power. The fastest method when the grid is up. The 2,000Wh-class units reach a full charge in about 1.4 to 1.8 hours on AC, according to Anker, BLUETTI and Jackery. Use this between storms to start with a full battery.
- A generator. A backup for a long run of cloudy days. Anker lists a generator input adapter for the F3800 Plus, and EcoFlow lists a Smart Generator that works with its larger systems. Check the model you are considering.
- Car or alternator charging. Slow, but it works when nothing else does.
- Load management. Run the pump only when you need water, and keep the refrigerator door closed. Every hour of pumping you skip saves about 1,000Wh.
On a cloudy day, your panels make a fraction of their rated output, and the battery covers the gap. That is why the plan pairs panels with at least a day of stored power, as shown in the solar table.
If the weather forecast shows several dim days, charge from the wall or a generator beforehand.
Common Mistakes to Avoid
- Buying a 120V-only power station for a 240V well pump.
- Sizing from running watts and ignoring the startup surge.
- Skipping the 20% margin for inverter losses and standby draw.
- Planning solar from the panel's label instead of real output (about 75% of rated watts) and your actual sun hours.
- Buying more panels than the power station can accept. Check its maximum solar watts and input voltage.
- Counting on solar alone with no battery cushion for nights and cloudy days.
- Plugging a power station into a wall outlet with a double-male cord to power the house. This can send power back into the utility lines and endanger line workers.
- Wiring the well pump yourself. Use a licensed electrician and a transfer switch, interlock kit or smart home panel.
- Guessing the pump's size. Read the nameplate for volts and amps.
All runtimes and recharge times on this page are estimates.
Real results depend on your appliance's age and size, the temperature, how often the door opens, the depth and flow rate of your well, and the weather.
If you depend on this equipment for something critical, plan for a margin beyond these numbers.
Frequently Asked Questions
How much battery does it take to run a refrigerator for 24, 48 and 72 hours?
Plan on about 1,500Wh for 24 hours, 3,000Wh for 48 hours and 4,500Wh for 72 hours. That is a typical full-size refrigerator (about 1,200Wh a day) plus a 20% margin for inverter losses.
How much battery does it take to run a refrigerator and one well pump?
About 2,750Wh for 24 hours, 5,500Wh for 48 hours and 8,250Wh for 72 hours, assuming a 240V half-horsepower pump that runs about an hour a day.
What about two well pumps?
About 4,000Wh for 24 hours, 8,000Wh for 48 hours and 12,000Wh for 72 hours, with the same one-hour-a-day assumption for each pump.
Can solar panels alone run a refrigerator?
In good sun, yes. About 400W of panels covers a typical refrigerator's daily energy, but the battery still carries it through the night and through cloudy stretches. Use the solar table above for your sun hours.
How long does solar take to recharge the battery?
It depends on three things: battery size, panel watts and sun hours. Use the recharge table above, or the formula: days to recharge = battery Wh ÷ (panel watts × 0.75 × peak sun hours). Winter, shade and clouds all lengthen it.
Do I need a 240V power station for a well pump?
Many residential well pumps run on 240V. If yours does, you need a 240V-capable power station or a system built for it. Check your pump's nameplate for voltage and amps, and plan for a startup surge of two to three times the running watts.
Can I plug my well pump into a power station?
Well pumps are usually hard-wired. A licensed electrician should install the connection through a transfer switch, interlock kit or home panel. Never feed a house through a double-male cord.
What if my pump trips the power station when it starts?
That is the startup surge. Choose a unit with enough surge capacity, and ask your installer whether a soft-start device is right for your pump.
How can I make the stored power last longer?
Run the pump only as needed, fill a tank or containers while power is available, keep the refrigerator closed, and turn off anything not essential. See the load-management section above.
What if the sun is not shining?
Recharge from wall power, a generator or your vehicle, where the power station supports it. See the section on other ways to recharge.
Which brand should I choose: EcoFlow, Jackery, BLUETTI or Anker?
Each has models that fit different scenarios. Use the configuration table above to match your target, or contact Power Fit Shop and we will help you size a system for your home and well.
