How many solar panels to run central air conditioning?
About 19 panels at 400 watts under national-average sun, working from 25 kWh a day. The count runs from 13 in desert sun to 21 in the cloudiest states. That answers the energy question; the timing question (this load at night, panels at noon) is the part most listicles skip, so it gets its own section below.
Panels by sun figure
400W panels, 0.77 derate, count rounded up; the right column shows what the rounded-up count actually produces against the load's 25 kWh day.
| Peak sun hours | Panels | Daily margin |
|---|---|---|
| 4.0 h | 21 | ~25.9 kWh vs 25 needed |
| 4.5 h (US avg) | 19 | ~26.3 kWh vs 25 needed |
| 5.0 h | 17 | ~26.2 kWh vs 25 needed |
| 5.5 h | 15 | ~25.4 kWh vs 25 needed |
| 6.0 h | 14 | ~25.9 kWh vs 25 needed |
| 6.5 h | 13 | ~26 kWh vs 25 needed |
Where the 25 kWh figure comes from. A 3-ton central unit draws about 3,500W running. Across a hot month it averages 6 to 8 compressor-hours a day: 21 to 28 kWh. We plan at 25 kWh a day, a real Sun Belt summer figure.
The part after the panel count
Nineteen panels at average sun, and that count deserves a slow look, because it says central AC in summer is roughly a whole average household's worth of energy by itself. This is why "solar for the AC" is rarely a separate project: at 19 panels you are simply buying a house system, and the right move is to size from the full bill (the calculator) rather than from one appliance. The one silver lining is timing, as with the window unit: the load peaks exactly when production does, and utilities with time-of-use rates price those afternoon kWh at their most expensive, which makes AC offset the most valuable production on the roof.
Before buying 19 panels, buy attic insulation and a smart thermostat. Cutting the duty cycle from 7 hours to 5 removes five panels from the math at a fraction of their price. The cheapest panel is the one the house stops needing.
Questions people ask
How many solar panels does it take to run central air conditioning?
About 19 400-watt panels at the national-average 4.5 peak sun hours, from a planning figure of 25 kWh a day. Strong desert sun brings it to 13; cloudy states need 21. Those counts cover daily energy; running the load at night takes a battery or a grid connection, covered below.
Can solar panels run central AC directly during an outage?
Not by themselves. Grid-tied inverters shut down in an outage by law (anti-islanding), and the compressor’s start surge of 15,000W-plus needs either a battery system with surge capacity or a soft-start kit. Whole-home battery systems handle it; a few panels and an extension cord do not.
Does this count include a battery?
No. The table answers the energy question: how many panels produce what the load consumes over a day. Grid-tied homes need nothing else; the grid absorbs the timing. Off-grid, add storage for the dark hours (the page discusses sizing for this load) and an inverter rated for the start-up surge where the load has one.