How Many Solar Panels For an Air Conditioner?
Air conditioning is power-intensive: a 10,000 BTU window unit draws 800-1,200W while running. For 8 hours of daily use, that's 6,000-10,000Wh. You need 1,000-1,200W of solar minimum, but 1,200W+ is recommended for reliable operation.
Determining the right number of solar panels for your needs is more nuanced than simply dividing your energy requirements by panel output. The actual panel count depends heavily on your geographic location, local climate patterns, and how you plan to use the energy. A homeowner in Arizona might need half as many panels as someone in Seattle for the same energy consumption, simply because of the dramatic difference in annual sunshine hours. Understanding these variables helps you design a system that reliably meets your needs without overspending on unnecessary capacity.
Solar panels work in concert with batteries and charge controllers to form a complete energy system. The panels generate electricity during daylight hours, but your battery bank stores that energy for use when the sun is not shining. This relationship means you cannot size panels in isolation - you must consider your battery capacity, daily energy consumption, and how many days of autonomy you want during cloudy weather. A well-designed system balances panel capacity with battery storage to ensure you have power when you need it, whether that is running essential appliances during a grid outage or powering a remote cabin year-round.
Seasonal variation presents one of the biggest challenges in solar system design. In most locations, winter produces significantly less solar energy than summer due to shorter days and lower sun angles. If you are designing for year-round off-grid use, you must size your system for the worst-case scenario: the shortest, cloudiest days of winter. This often means your system will produce excess energy during summer months, which can be managed through load diversion (like heating water) or simply accepted as part of reliable system design. Grid-tied systems can offset this by drawing from the utility during low-production periods and exporting surplus during peak production.
The distinction between off-grid and grid-tied systems fundamentally changes your sizing strategy. Off-grid systems must be self-sufficient, requiring enough panels and batteries to handle your entire load plus a safety margin for extended cloudy periods. This typically means oversizing by 25-50% compared to average daily needs. Grid-tied systems can be sized more precisely to offset your annual consumption, since the utility provides backup during low-production periods. Hybrid systems with battery backup offer a middle ground, providing resilience during outages while still benefiting from grid connectivity. Your choice between these configurations significantly impacts both the number of panels needed and the overall system cost.
Minimum
6panels
100W each
Recommended
10panels
100W each
Ideal
12panels
100W each
Daily Need
6.0kWh
Calculation basis: 10,000 BTU window AC running 8 hours/day
Panels Needed by Size
Based on 5 peak sun hours and 80% system efficiency.
| Panel Size | Daily Output | Panels Needed | Total Watts |
|---|---|---|---|
| 100W | 400Wh/day | 15 | 1500W |
| 200W | 800Wh/day | 8 | 1600W |
| 400W | 1600Wh/day | 4 | 1600W |
Factors That Affect Panel Count
The calculations above assume 5 peak sun hours (US average). Adjust based on your location:
Southwest US
6-7 peak sun hours
Need ~20% fewer panels
Central/Southeast
4-5 peak sun hours
Use our estimates
Northern/Pacific NW
3-4 peak sun hours
Need ~25-40% more panels
Tips
- *Mini-split ACs are 30-50% more efficient than window units
- *Insulate your space well—it's cheaper than more solar
- *Use the AC during peak sun hours when panels are producing
- *A soft-start device reduces startup surge significantly
For an Air Conditioner, you'll also need battery storage for nighttime and cloudy periods.
Minimum Battery
625Ah
~12 hours autonomy
Recommended Battery
1250Ah
~24 hours autonomy
Frequently Asked Questions
Can I run AC off-grid?
Yes, but it requires a substantial system. A 10,000 BTU AC needs about 1kW of solar per 3-4 hours of runtime, plus battery storage for startup and evening use.
What inverter size for air conditioning?
3,500-5,000W pure sine wave inverter for a 10,000 BTU unit. The high startup surge requires significant headroom.
Are mini-splits worth the extra cost?
For off-grid, absolutely. Mini-splits use 30-50% less power, have lower startup surge, and provide both heating and cooling.