RV AC Solar Calculator

Can your solar system run the air conditioner? Get a battery drain rate, recharge rate, and clear verdict.

AC unit

AC unit size?

Hours of AC use per day?

hrs/day

Your existing solar system

Solar panel array size?

Battery capacity?

kWh

Peak sun hours?

hrs/day

Feasibility verdict

✓ Feasible

Feasible — your solar system can support this AC usage.

AC daily demand5.4 kWh/day

Solar daily output8.8 kWh/day

Battery on AC alone5.9 hrs

Solar recharge rate1,600 W (surplus)

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How to Use This Calculator

Select your AC unit

The four AC options cover the most common RV configurations. 5,000 BTU (600W) is a small portable or window unit. 8,000 BTU (900W) is a mid-range portable. 13,500 BTU (1,350W) is the standard Dometic/Coleman rooftop unit found on most Class A and Class C RVs. 15,000 BTU (1,500W) is the large rooftop unit for hot climates.

Enter hours per day

Be realistic about your AC usage pattern. Running AC 4 hours in the afternoon is very different from running it overnight. An average of 4 hours/day is typical for afternoon desert use. Running overnight (8-10 hours) requires a much larger battery bank — typically 15-20 kWh of lithium.

Check your existing system

Enter your current solar panel total wattage and battery capacity. To convert battery Ah to kWh: multiply Ah by volts and divide by 1,000. Example: 200Ah at 12V = 2.4 kWh. Note that only 80% of lithium capacity is usable (vs. 50% for lead-acid).

Interpret the verdict

The calculator gives a green/yellow/red verdict. Feasible means your solar fully replenishes what the AC uses daily. Partial means your battery can run the AC but solar may not fully recharge it every day — fine for occasional use, not for daily operation. Not feasible means both battery and solar are undersized; the system will deplete over several days.

The Formula

AC Daily kWh = AC Watts × Hours/day ÷ 1000 Solar Daily kWh = Solar Watts × Peak Sun Hours × 0.80 ÷ 1000 Battery Usable kWh = Battery kWh × 0.80 (lithium DoD) Hours on Battery = Battery Usable kWh ÷ AC kW Solar Recharge Rate (W) = Solar Watts × 0.80 Feasible: Solar Daily kWh ≥ AC Daily kWh AND Battery covers full cycle Partial: Battery covers AC but Solar Daily kWh < AC Daily kWh Not feasible: Battery hours < 70% of AC hours needed

The critical insight: a 13,500 BTU rooftop AC running 4 hours consumes 5.4 kWh per day. Most standard RV solar systems (400-800W) produce only 1.6-3.5 kWh per day. You'd need 2,000W+ of solar to sustainably run a rooftop AC daily in the desert Southwest.

Example

Full-timer scenario — Arizona summer

Maria has a Class A with a 13,500 BTU rooftop AC. She wants to run it from 2pm-6pm daily (4 hours) in Arizona (5.5 peak sun hours). She has 2,000W of solar and a 10 kWh lithium battery bank.

AC draw1,350W × 4h = 5.4 kWh/day

Solar output2,000W × 5.5h × 80% = 8.8 kWh/day

Battery usable10 kWh × 80% = 8 kWh

Result

VerdictFeasible

Solar surplus over AC+3.4 kWh/day

Battery runtime (AC only)5.9 hours

With 2,000W of solar in Arizona, the system produces 8.8 kWh — well above the 5.4 kWh the AC uses. The surplus covers all other RV loads too. The battery provides a 6-hour buffer for cloudy afternoon starts. This is a well-sized system for daily afternoon AC use in the desert Southwest.

FAQ

Can you run RV AC on solar power? ▼

Yes, but it requires a serious investment. The minimum practical setup for running a 13,500 BTU rooftop AC for 4 hours/day is approximately 2,000W of solar and 10 kWh of lithium battery. Running it overnight (8 hours) requires 15-20 kWh of battery and 3,000W+ of solar. The math works in sunny climates; cloudy days are the challenge.

What size battery do I need to run RV AC all night? ▼

Running a 13,500 BTU AC (1,350W) for 8 hours overnight: 1,350W × 8h = 10.8 kWh. With lithium (80% usable), you need a 13.5 kWh battery bank. With AGM (50% usable), you'd need 21.6 kWh. Popular choices: four 200Ah lithium batteries at 24V = 19.2 kWh (giving headroom). Budget approximately $4,000-8,000 for the battery bank alone. Add 2,000-3,000W of solar to recharge the next day.

What are soft starters for RV AC and do I need one? ▼

AC compressors draw 3-6x their running wattage at startup (called the "locked rotor amps"). A 1,350W AC might surge to 6,000W at startup for 1-2 seconds — exceeding the capacity of most inverters. A soft starter (EasyStart, Micro-Air) reduces startup surge by 50-75%, allowing a 3,000W inverter to start a 13,500 BTU AC that would otherwise need a 6,000W inverter. Essential for any solar-powered AC installation.

What inverter do I need for RV AC? ▼

Without a soft starter: a 13,500 BTU AC needs a 3,500-4,000W pure sine wave inverter. With a soft starter: a 3,000W inverter can handle it. For a 15,000 BTU unit, add another 500W of inverter capacity. The inverter must be pure sine wave — modified sine wave inverters cause AC motors to run hot and fail prematurely. Popular options: Victron MultiPlus, Renogy 3000W, Xantrex Freedom.

Is it worth adding AC capability to my RV solar system? ▼

Depends on your climate and camping style. If you camp exclusively in moderate temperatures or at elevation, a good fan ventilation system and shade placement can keep an RV comfortable without AC. If you camp in the Southwest or Southeast US in summer, AC is a quality-of-life necessity. Budget $5,000-10,000 to add AC capability (2,000W solar + 10kWh lithium + 3,000W inverter + soft starter) to an existing basic solar system.