How Much Solar Do You Need to Run an RV Air Conditioner?

1. Why AC is the hardest thing to run on solar

An RV air conditioner is two hard problems stacked. The first is the startup surge: when the compressor kicks on, it briefly pulls roughly 2,500 to 3,500 watts — multiples of its running draw — for a fraction of a second. An undersized inverter cannot pass that surge and will drop the load.

The second is the continuous draw. Once it’s running, a typical 13,500 BTU rooftop unit pulls roughly 1,300 to 1,800 watts. On a hot day cycling most of the afternoon, that totals well over 5,000 watt-hours — several times what a small system makes in a whole day.

Nothing about that math fits a small array. AC is not a load you bolt onto a 400W setup. It’s a build from the ground up.

2. The honest solar sizing

To run AC for a real stretch in real heat, the array starts around 1,000 watts and climbs from there. For sustained midday use in hot climates, plan on 1,500 to 2,000-plus watts of rooftop solar, plus tiltable portables if you can carry them.

The inverter has to be 3,000 watts or more, pure-sine, and explicitly rated to pass the surge of your specific AC. “Soft start” modules reduce the surge and let a smaller inverter handle it — a worthwhile add-on.

The battery bank carries the part of the day the panels can’t. That bank needs to be sized for the kilowatt-hours of AC use you actually want, which is a real number worth working out before you buy anything. Battery sizing has its own tradeoffs (chemistry, depth of discharge, weight) that the future Battery cluster will cover in depth.

3. The generator shortcut

A small inverter generator running two to three hours during the hottest part of the afternoon roughly halves the solar and battery you would otherwise need. It also runs the AC directly while it runs, charging the bank at the same time.

The honest tradeoff: a generator is far cheaper up front than the solar and battery build it replaces, but it adds fuel, noise, and a tool you have to maintain. Many campgrounds and some popular boondocking areas have generator-hour limits or quiet hours, too. The full solar-vs-generator comparison is its own post, planned for the next wave.

4. How we actually stayed cool

We did not size our rig for AC on solar — not even close. So we beat the heat the way most boondockers do.

A few tactics that actually moved the needle: gain elevation when you can — a few thousand feet up takes ten or more degrees off the afternoon. Park the rig long-axis north-south so one side is always shaded. Crack the roof vents and put a small 12V fan in line for a real cross-breeze. And know when to leave: if the forecast is 100 and the spot has no shade, drive an hour and find somewhere it’s 80.

5. If you still want AC on solar, size it honestly

Some rigs and routes really do need it. Larger families, hot regions in summer, work-from-the-road that demands a quiet rig — all valid. The path is to write down the kilowatt-hours of AC use you want and build the array, bank, and inverter against that number.

RV solar, frequently asked