How Many Solar Panels to Run an Air Conditioner? 

Running your AC on solar isn’t just possible—it’s one of the smartest ways to beat rising energy costs. Here’s exactly how to size your system, with real-world examples.

⚡ Quick Answer

Most air conditioners need:

• 600–1,200W solar panels per ton (12,000 BTU)
• Lithium batteries for overnight cooling
• Example: An 8k BTU window AC requires 400–600W solar + 200Ah battery

🔢 Get Your Exact Numbers (Our solar calculator pre-loaded with AC data)

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🔌 AC Power Requirements

Air conditioners have two critical wattage numbers:

1. Running watts (continuous power)
2. Surge watts (3x higher at startup)

AC Type	Running Watts	Surge Watts
Window (8k BTU)	900W	2,700W
Central (3 ton)	3,500W	10,500W

Source: EnergyStar AC Database

☀️ Solar Calculation

Step-by-Step Formula:

(Daily Watt-hours ÷ Sun Hours) × 1.3 = Solar Watts Needed

Example for 8k BTU AC:

1. Daily usage: 900W × 6 hours = 5,400Wh
2. Sun hours: 4 (adjust via NREL map)
3. Add 30% buffer: (5,400 ÷ 4) × 1.3 = 1,755W solar

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🔋 Battery Backup Guide

Lithium vs. Lead-Acid:

Metric	Lithium	Lead-Acid
Cycles	3,000+	500
Depth of Discharge	80%	50%
Cost per kWh	$600	$300

Rule of Thumb:

*”100Ah lithium battery = ~1 hour of runtime for 3-ton central AC”*

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💰 Cost Breakdown

Window AC System:

• 400W solar panels: $800
• 200Ah lithium battery: $1,200
• Inverter/charger: $600
• Total: $2,600 (before tax credits)