Solar Panels for AC add-on system

Understanding AC Wattage: The Starting Point for Solar Panel Sizing

Before you can figure out how many panels you need, you have to know how much power your air conditioner actually consumes. This is where most online estimates go wrong — they use nameplate capacity (BTUs) instead of real running wattage, which overstates or understates consumption depending on the unit’s efficiency.

A 1-ton AC unit (12,000 BTU) typically draws 900–1,200 watts when running. A 2-ton unit (24,000 BTU) draws roughly 1,800–2,500 watts. A standard 3-ton central AC — the most common size in US homes — pulls 3,000–4,000 watts during the cooling cycle. Larger 4- and 5-ton systems used in bigger homes can reach 5,000–6,000 watts at peak draw.

The efficiency rating matters enormously. A unit with a SEER (Seasonal Energy Efficiency Ratio) rating of 14 uses noticeably more electricity than a SEER-20 unit delivering identical cooling output. According to the U.S. Energy Information Administration (EIA), air conditioning accounts for about 17% of total US residential electricity use — and in hot states, that figure climbs far higher. In Florida, where cooling demand runs nearly year-round, AC can represent 40–50% of a home’s annual electricity bill.

To calculate your AC’s daily energy consumption, multiply its running wattage by the average hours it operates per day. A 3,500-watt central AC running 8 hours uses 28 kilowatt-hours (kWh) per day. That’s the target your solar array needs to match.

Window units are the most efficient option for cooling a single room. A typical 8,000 BTU window AC draws just 550–700 watts — meaning 2–3 solar panels could cover its daytime operation. Mini-split systems fall in between, with a modern inverter-driven 1.5-ton mini-split often pulling as little as 1,100 watts thanks to variable-speed compressor technology.

One underappreciated factor is the startup surge. Air conditioners draw 2–3× their running wattage for the first few seconds when the compressor kicks on. A grid-tied solar system handles this automatically, but off-grid setups need an inverter rated to handle that peak load without tripping a breaker or shutting down mid-cycle.

Cost and Payback: What Solar AC Actually Costs in 2026

The panel and battery math eventually comes down to dollars. Here’s what a solar-for-AC setup realistically costs in 2026, before incentives.

A grid-tied solar system sized to offset a 3-ton AC — roughly 11–14 panels at 400 watts each — costs approximately $8,000–$14,000 installed, depending on your installer and location. At the national average electricity rate of $0.16/kWh (EIA 2025 residential data), that 3-ton AC running 8 hours/day for 5 summer months costs roughly $1,100 per year to operate. Solar payback for just the AC portion of your load typically falls between 7 and 11 years without incentives.

The federal solar Investment Tax Credit (ITC) currently sits at 30% under the Inflation Reduction Act, cutting that $14,000 system to an effective $9,800 out of pocket. State incentives can reduce costs further — Arizona homeowners pay no state income tax on solar credits, and New York offers an additional 25% state tax credit capped at $5,000. Combined, federal and state incentives can reduce total system cost by 40–55% in the most generous states, dramatically shortening payback periods.

For a mini-split-focused setup (4–7 panels), installed costs drop to $3,500–$6,000, and payback periods shrink to 5–8 years even before incentives. That’s a meaningful difference for homeowners cooling one or two rooms rather than an entire house.

If you’re adding a new mini-split alongside solar — a common and cost-effective combination — total project cost for panels, inverter, and mini-split installation typically runs $8,000–$15,000. You’re replacing both your AC system and a significant portion of your electricity bill in a single project. To see exactly what you’d keep after federal and state credits based on your zip code, use the solar tax credit calculator.