How many solar panels do I need for an air conditioner?

Running an air conditioner on solar is absolutely possible, but you need to size it right: it's likely the largest single load in your home, and it gets used precisely when the sun is up — which actually works in your favour. Here's the formula plus three real examples by unit size.

Real consumption by size

A modern inverter mini-split uses far less than an old on/off unit. Typical running watts (not surge):

• 9,000 BTU (≈ 0.75 ton): 600-900 running watts
• 12,000 BTU (1 ton): 900-1,300 running watts
• 18,000 BTU (1.5 ton): 1,400-2,000 running watts
• 24,000 BTU (2 ton): 1,900-2,700 running watts

Example: 12,000 BTU inverter, 6 hours a day

Assume 1,000 W average × 6 hours = 6 kWh/day. With 4.5 peak sun hours and a 1.3 loss factor: 6,000 ÷ 4.5 × 1.3 = 1,733 W of panels. You need 4-5 × 410-450 W panels. Since the AC runs during the day, most power flows directly from panel to unit without going through a battery — huge advantage.

Do I need a battery?

If you only use AC during the day and have grid backup, you don't need a battery: surplus sun exports under net metering. For nighttime cooling or off-grid, size a 10-15 kWh lithium bank to run the AC for 4-6 hours after sunset.

Tricks to reduce panel count

• Pick high-SEER inverter units (30-40% less consumption)
• Insulate the room (double-pane windows, blinds, weatherstripping)
• Schedule the AC to pre-cool an hour before peak heat, riding the solar curve
• Consider a hybrid DC solar AC unit for pure off-grid setups

If you combine AC with a solar fridge and other loads, total it up with our whole-home sizing guide. To decide about storage, see when a solar battery is worth it.