Solar Panels for Air Conditioner Calculator

Running an air conditioner on solar

The AC is usually the biggest single load in a hot-climate home, so it is the appliance people most want solar to carry. The good news: modern inverter ACs pair very well with solar, because their compressor throttles down once the room is cool and the average draw falls well below the nameplate. A 1.5-ton inverter AC typically averages 1.1–1.2 kW while running; over 8 hours that is roughly 9 kWh a day — which, at 5 peak sun hours, takes about a 2.2 kW array, or 4–5 modern 540 W panels, once real-world losses are counted.

Day vs night is the real question

Panels only produce in daylight, so what matters most is when you run the AC. Daytime cooling can run directly off the array. Night-time cooling needs storage: every night kWh must first be banked in a battery, which adds cost and losses. If you mainly cool bedrooms overnight, expect the battery — not the panels — to dominate the budget. An honest split of your running hours between day and night (the input above) changes the answer far more than panel brand ever will.

Fixed-speed ACs are harder on solar

A fixed-speed AC draws full power whenever the compressor is on and surges to several times its rating at each restart. That surge forces a larger inverter (roughly 3× the rated draw, unless you fit a soft-starter), and the on/off cycling suits batteries poorly. If you are buying an AC to run on solar, an inverter model with a high ISEER rating is worth the premium — it can cut the panels needed by a third.

Sizing beyond one AC

This tool sizes solar for the AC alone. To power the AC plus the rest of the house, add your other loads in the load calculator, or size a full system with the off-grid calculator or the mini-split tool if you are still choosing the AC itself.

Frequently asked questions

Around 4 to 5 modern 540 W panels (a ~2.2 kW array) for 8 hours of daily use at 5 peak sun hours — assuming an inverter AC averaging about 1.1 kW. Fixed-speed units and longer hours need more; run your own numbers above.

Yes, during daylight — a grid-tied or hybrid inverter runs daytime cooling straight off the array. Night-time cooling needs a battery or the grid, which is why the day/night split input matters so much.

Roughly the night-time kWh divided by 0.72 (90% round-trip efficiency times 80% usable depth). Four hours of a 1.5-ton inverter AC (~4.5 kWh) needs about a 6 kWh battery. Night cooling is usually the most expensive part of a solar AC setup.

Yes — once the room reaches temperature it throttles the compressor instead of stopping and restarting, typically averaging 25–40% less energy than a fixed-speed unit of the same tonnage, and it starts gently, so a smaller solar inverter suffices.