How many solar panels to run a mini split?
A 12,000 BTU mini split drawing about 1,200 W for 8 compressor hours uses about 10,667 Wh a day through an inverter. At 4.5 peak sun hours, with a quarter of that from a battery, it takes about 2,816 W of panels — 8 panels of 400 W.
How to work it out
- 1,200 W × 8 h ÷ 90% inverter = 10,667 Wh a day
- 25% through a battery at 92% round trip → 10,899 Wh from the panels
- ÷ (4.5 sun h × 86%) = 2,816 W → 8 panels of 400 W
Mini splits are an efficient way to cool (and often heat) a single room or small cabin, and the variable-speed ones slow down once the room is comfortable. That makes the spec sheet’s rated input watts — and your own measurements — far better than a rule of thumb here.
Adjust for your project
More options: From battery · Losses
- Solar array needed
- 2,816 W
- Energy per day (from the system)
- 10,667 Wh
- LiFePO4 battery for the night share (12.8 V)
- 260 Ah
- Figures used
- 1,200 W × 8 h a day (typical)
- 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.
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 | 469 W | 2 panels |
| Chest or upright freezer | 1,333 Wh | 352 W | 1 panel |
| CPAP (no heated humidifier) | 533 Wh | 141 W | 1 panel |
| Window AC, 10,000 BTU | 8,889 Wh | 2,347 W | 6 panels |
| Mini-split, 12,000 BTU | 10,667 Wh | 2,816 W | 8 panels |
| Pool pump (example: 1,900 W input) | 16,889 Wh | 4,459 W | 12 panels |
What to know about a mini split on solar
- Use the spec sheet. Mini-split spec sheets list rated input power for cooling and heating. Many inverter-driven units draw well under their maximum once the room is at temperature; 1,200 W for 8 hours is a cautious planning figure.
- Daytime cooling matches the sun. Air conditioning is needed most when the sun is strongest, so most of the energy can be used as it is made, with only a quarter going through the battery here. It still needs a battery-based inverter to run at all — a grid-tied inverter can’t power loads on its own and shuts down in an outage.
- Nights get expensive. Running the same unit all night from batteries would take roughly 1,040 Ah of 12.8 V LiFePO4 for 8 hours — a very large bank.
- Heating is a different load. In heat mode the draw and hours depend on the outdoor temperature; a cold night can mean many more hours than cooling.
Compare a window unit on the cost to run a window AC unit. For a whole cabin system around this load, see how many solar panels for a small cabin; for a pump instead, how many solar panels to run a pool pump.
Different size? Use the full Solar Panels for One Appliance.
What you’ll need
- 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) - MPPT solar charge controllerMid-range price
Converts a higher panel voltage into charging current, so you can wire panels in series and lose less in the cables. Size it on output amps and maximum PV voltage.
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)
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 to run a 9,000 BTU mini split?
About 2,112 W — 6 panels of 400 W — at 900 W for 8 hours.
How many solar panels to run a mini split only during the day?
About 2,756 W — 7 panels of 400 W — with little battery energy, though it still needs a battery-based inverter (or a grid connection) to run.
Other common sizes
- 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 pool pump — 11 × 400 W panels for a 1,900 W pump (example)
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%.