What Size Solar Panel Do I Need for a Box Fan / Ceiling Fan?

50W running draw8h/day defaulthvac

Quick Answer

A Box Fan / Ceiling Fan at 50W needs at least 200W of solar panels to run sustainably. Running 8 hours per day draws 400 Wh daily. A single 200W solar panel covers it. Pair with a 100Ah LiFePO4 battery at 12V for 2-day cloudy weather reserve. The EcoFlow River 2 is the simplest all-in-one solution for this load.

System Specs for a Box Fan / Ceiling Fan

Calculated for 8 hours/day usage, 5 peak sun hours, and 2-day LiFePO4 battery autonomy.

ComponentMinimum SizeDetails
Daily Energy400 Wh50W for 8h
Solar Panels200W1x 200W panel covers it
Battery100Ah at 12VLiFePO4, 2-day reserve (1.2 kWh usable)
Charge Controller30A MPPTHandles up to 200W panel input at 12V

Running more than just a box fan / ceiling fan? Add more appliances to your load with our full calculator

Recommended Power Station

EcoFlow River 2

256Wh capacity, 300W AC output — ideal for phones, laptops, CPAP, and small electronics.

256Wh

Capacity

300W

AC Output

110W

Max Solar In

Buy on EcoFlow.comView with Solar Panel Bundle

DIY Component List

Building your own system for a box fan / ceiling fan? These components match the specs above.

Solar Panel

200W total

Renogy 200W 12V Monocrystalline on Amazon

Battery

100Ah 12V LiFePO4 minimum

LiTime 12V 100Ah LiFePO4 on Amazon

Charge Controller

30A MPPT minimum

Renogy 40A MPPT Rover on Amazon

About the Box Fan / Ceiling Fan Solar Load

A standard box fan draws 40–70 watts on high speed, averaging about 50 watts. Running 8 hours per day uses 400Wh. Ceiling fans with DC motors draw as little as 15–30 watts and run directly on 12V in an RV or van. Fans are the most efficient cooling option for solar systems and should always be tried before sizing for an air conditioner.

Frequently Asked Questions

How much solar do I need to run a fan all day?▼
A box fan at 50 watts running 8 hours per day uses 400Wh. A 100W solar panel generates 400–500Wh on a sunny day, making it a near-perfect single-panel application. For 24-hour fan use (sleeping plus daytime), daily consumption is 1,200Wh, requiring a 300–400W solar array plus a 100Ah LiFePO4 battery to cover nighttime hours. DC-motor ceiling fans like the Hunter Outdoor or Haiku fans draw only 15–25 watts and run 24 hours on just 400Wh per day.
Can I run a 12V fan directly from solar without a battery?▼
A dedicated 12V solar fan can run directly from a solar panel through a charge controller, but output will fluctuate with clouds and stop at night. For daytime-only cooling in a greenhouse or shed, this works fine. For sleeping, you need a battery so the fan runs through the night. A 12V DC fan like the Endless Breeze or the Maxxair vent fan draws 2–5 amps at 12V and runs all night on a 50Ah battery. Pair it with a 100W panel and a 10A MPPT controller for a complete setup under $200.
Is a fan enough cooling for a van in summer?▼
In mild climates and shoulder seasons, a rooftop vent fan like the MaxxAir or Fan-Tastic Vent draws 1–4 amps at 12V and creates meaningful airflow through a van. In peak summer heat above 90°F, a fan moves hot air efficiently but does not provide cooling by itself without a cross-breeze. At that point, many van lifers use a 12V portable air conditioner like the BougeRV or Zero Breeze Mark 2. These draw 150–200 watts at 12V and are sized to solar. A fan keeps the van livable; the portable AC handles extreme heat days.

Related Hvac Appliances

Air Conditioner (window / mini-split)

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Electric Blanket

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Space Heater (electric)

1500W running draw

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Pellet Stove

100W running draw

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Running more than just a box fan / ceiling fan?

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