How many solar panels to run an appliance?
Pick the appliance and enter its watts and running hours if you know them — leave them blank to use a typical figure. The calculator sizes the panels and the battery for the share used after dark.
Enter your measurements
More options: From battery · Losses
- Solar array needed
- 479 W
- Energy per day (from the system)
- 1,778 Wh
- LiFePO4 battery for the night share (12.8 V)
- 87 Ah
- Figures used
- 200 W × 8 h a day (typical)
200 W × 8 h ÷ 90% inverter = 1,778 Wh a day
50% through a battery at 92% round trip → 1,855 Wh from the panels
÷ (4.5 sun h × 86%) = 479 W → 2 panels of 400 W
- Champion lists 150–400 running watts; a fridge runs at full power about a third of the time (Virginia Cooperative Extension).
Quick answers for common sizes
| Example | Answer |
|---|---|
| How many solar panels to run a refrigerator | 2 × 400 W panels (479 W) plus about 87 Ah of battery |
| How many solar panels to run a mini split | 8 × 400 W panels (2,816 W) |
| How many solar panels to run a pool pump | 11 × 400 W panels for a 1,900 W pump (example) |
Panels for each appliance at the sun hours above
| Appliance | Energy per day (from the system) | Solar array needed | Panels |
|---|---|---|---|
| Refrigerator (household) | 1,778 Wh | 479 W | 2 panels |
| Chest or upright freezer | 1,333 Wh | 360 W | 1 panel |
| CPAP (no heated humidifier) | 533 Wh | 144 W | 1 panel |
| Window AC, 10,000 BTU | 8,889 Wh | 2,397 W | 6 panels |
| Mini-split, 12,000 BTU | 10,667 Wh | 2,876 W | 8 panels |
| Pool pump (example: 1,900 W input) | 16,889 Wh | 4,554 W | 12 panels |
Worked examples: how many solar panels to run a refrigerator, how many solar panels to run a mini split and how many solar panels to run a pool pump.
How it is worked out
Wh per day = running watts × running hours ÷ inverter efficiency from the panels = Wh used directly + Wh through the battery ÷ battery round-trip efficiency array W = Wh from the panels ÷ (peak sun hours × (1 − losses)) battery Ah = Wh from the battery ÷ 80% usable ÷ 12.8 V
Appliances here are assumed to run on AC through an inverter (90%, the low end of Victron’s “above 90%”). Energy that goes into a LiFePO4 battery and back out loses about 8% (Victron’s 92% round trip). System losses default to PVWatts’ 14%.
Typical figures used when you leave watts blank
| Appliance | Watts used | Hours a day | Source of the range |
|---|---|---|---|
| Refrigerator (household) | 200 | 8 | Champion lists 150–400 running watts; a fridge runs at full power about a third of the time (Virginia Cooperative Extension). |
| Chest or upright freezer | 150 | 8 | Champion lists 100–500 running watts for freezers. Read the EnergyGuide label’s kWh per year if you have it. |
| Mini-split, 12,000 BTU | 1,200 | 8 | Use the rated input watts on the unit’s spec sheet. Champion’s figures for window and central air conditioners work out to roughly 8–11 BTU per watt; 12,000 BTU at 10 BTU per watt is 1,200 W. Inverter mini-splits often draw less once the room is cool. |
| Window AC, 10,000 BTU | 1,000 | 8 | Champion lists 900–1,200 running watts for a 10,000 BTU window unit, 450–600 W for 5,000 BTU. |
| Pool pump (example: 1,900 W input) | 1,900 | 8 | A 1.5 hp motor is 1,119 W of shaft power (746 W per hp); the electrical input is higher. 1,900 W is only an example input — use amps × volts from your pump’s label. ENERGY STAR: half speed uses about one-eighth the energy. |
| CPAP (no heated humidifier) | 60 | 8 | Champion lists 30–60 W without heat, 60–120 W with a heated humidifier. |
Running motors on solar
- Starting surge. Compressors and pump motors draw several times their running watts for a moment. The inverter must cover it — Champion lists 800–1,200 starting watts for a household fridge. See the inverter size calculator.
- Daytime is cheap, night is expensive. Energy used while the sun shines comes straight from the panels; energy used at night needs battery, which costs far more per kWh than panel.
- Grid-tied is different. With a grid connection and net metering, you can size panels on yearly kWh and let the grid act as the battery — see the solar system size calculator.
What you’ll need
- Plug-in electricity usage monitorBudget price
Plugs in between the wall and a 120 V appliance and shows real watts and kWh over a day — the honest way to fill in a load list, especially for fridges that cycle on and off.
See options on Amazon (opens in a new tab) - 400 W residential-size solar panelPremium price
Fewer, larger panels for a cabin, shed or ground mount. Their higher voltage usually means an MPPT controller.
See options on Amazon (opens in a new tab) - 12 V 100 Ah LiFePO4 batteryPremium price
About 1.28 kWh rated in a box roughly the size of a group 24–31 lead-acid battery at around half the weight. Check the BMS discharge limit and whether it can charge below freezing.
See options on Amazon (opens in a new tab) - Pure sine wave inverter, 2000–3000 WPremium price
For microwaves, coffee makers and power tools. At 12 V these draw hundreds of amps, so the battery and cabling matter as much as the inverter.
See options on Amazon (opens in a new tab)
As an Amazon Associate we earn from qualifying purchases. Links to products are affiliate links — they cost you nothing extra and help keep these calculators free.
Frequently asked questions
How many solar panels does it take to run a refrigerator?
A fridge running 200 W about a third of the time uses about 1,778 Wh a day through an inverter. At 4.5 peak sun hours that is about 480 W of panels — two 400 W panels — with half its energy coming from a battery overnight. See how many solar panels to run a refrigerator.
Can a solar panel run an air conditioner?
Yes, with enough of them: a 10,000 BTU window unit at about 1,000 W for 8 hours needs roughly 2,300 W of panels in daytime, and far more battery to run it at night. See how many solar panels to run a mini split.
How many solar panels to run a pool pump?
Use the input watts on the pump’s label: a 1.5 hp motor is 1,119 W of shaft power and draws more at the plug. A pump drawing 1,900 W for 8 daytime hours takes about 4,360 W of panels at 4.5 sun hours. A variable-speed pump at lower speed can cut that sharply. See how many solar panels to run a pool pump.
How many solar panels to run a CPAP?
A CPAP using 60 W for 8 hours a night is about 533 Wh through an inverter, all from a battery — roughly 150 W of panels at 4.5 sun hours to refill it, and about 52 Ah of 12.8 V LiFePO4.
Sources
- Champion Power Equipment — Generator Wattage Chart (opens in a new tab) — Typical running and starting watts for household, RV and job-site appliances (a manufacturer’s planning chart — your nameplate wins).
- Virginia Cooperative Extension, BSE-301: Estimating Appliance and Home Electronic Energy Use (2020) (opens in a new tab) — Wattage × hours ÷ 1,000 = kWh per day; watts = amps × volts when only amps are listed; a refrigerator runs at full wattage about a third of the time; typical nameplate wattages.
- ENERGY STAR — Pool pumps (opens in a new tab) — Running a pool pump at half speed uses about one-eighth as much energy.
- Victron Energy — Energy Unlimited (book) (opens in a new tab) — Lead-acid charge efficiency 80–95% (85% suggested as a starting value); battery energy efficiency about 75% for full cycles, about 89% in partial state of charge; inverter efficiencies above 90%.
- Victron Energy — Lithium Battery Smart manual, technical data (opens in a new tab) — LiFePO4 12.8 V: cycle life 2,500 at 80% DoD, 3,000 at 70%, 5,000 at 50% (to 80% of capacity); 92% round-trip efficiency; 12.8 V 100 Ah: recommended continuous discharge ≤100 A (1C), maximum 200 A; capacity about 20% lower at 0 °C; charge only between +5 °C and +50 °C.
- National Laboratory of the Rockies (formerly NREL) — PVWatts® Calculator (opens in a new tab) — Look up the solar resource (peak sun hours) and yearly output for your own address; default system losses 14%.